Subject: Re: Mount Hood... From: Bob Fryer bfryer@............ Date: Sun, 30 Jun 2002 12:31:54 -0700 Hello Kareem, I live west of Portland, Oregon, about the same distance from Mt St Helens and Mt Hood. We've been ashed... I witnessed several of the 1980 eruptions. Mt Hood has a history of erupting after Mt St Helens, according to some sources. Mt Hood last erupted just 200 years ago. Episodes like this have occurred several times in the last few years, at several locations on the South side of the mountain. This sequence is about 3 miles SSE of the summit. It has slowed considerably. See yesterday's activity at: http://www.ess.washington.edu/SEIS/PNSN/WEBICORDER/TDH_EHZ_UW.2002062912.html See today's activity at: http://www.ess.washington.edu/SEIS/PNSN/WEBICORDER/TDH_EHZ_UW.2002063012.html There are live fumaroles high on the mountain, about 800 feet below the summit. You could see the gases venting in the videos taken a few weeks ago at the site of a fatal climbing accident, and the helicopter crash which occurred during the rescue operations. While I knew of the fumaroles, I had never 'seen' them; I was startled by the level of activity. I don't know if this activity level was unusual. See the USGS Cascades Volcano Observatory (CVO) at: http://vulcan.wr.usgs.gov/ Early this May, I talked for several hours with Drs. Rauscher and van Bise who predicted the eruption of Mt St Helens, and many earthquakes over the past 20 years. They said they detected signals from St Helens in October or November of 1979, months before geophysicists were surprised by the early eruptive events. (You can see information about them on my website. Look at the bottom of this post. I will be adding information about their work.) Take care, Bob Fryer >What's everyone's guess about Mt. Hood in Oregon or have you been >following? There have been a remarkable number of quakes near the >cone. Yesterday morning's swarm started with a M4.8 bang and it was >followed by at least forty aftershocks. > >Is she telling us something? > >Kareem -- earthquake WARNING research Animals, People, Scientific Evidence www.earthquakewarning.org __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Mount Hood... From: "kArEEm" temp@............. Date: Mon, 1 Jul 2002 06:40:26 -0700 I knew someone would know the history of Mt. Hood; that's why I mentioned it. Thanks for the background info. -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Bob Fryer Sent: Sunday, June 30, 2002 12:32 PM To: psn-l@.............. Subject: Re: Mount Hood... Hello Kareem, I live west of Portland, Oregon, about the same distance from Mt St Helens and Mt Hood. We've been ashed... I witnessed several of the 1980 eruptions. Mt Hood has a history of erupting after Mt St Helens, according to some sources. Mt Hood last erupted just 200 years ago. Episodes like this have occurred several times in the last few years, at several locations on the South side of the mountain. This sequence is about 3 miles SSE of the summit. It has slowed considerably. See yesterday's activity at: http://www.ess.washington.edu/SEIS/PNSN/WEBICORDER/TDH_EHZ_UW.2002062912 ..html See today's activity at: http://www.ess.washington.edu/SEIS/PNSN/WEBICORDER/TDH_EHZ_UW.2002063012 ..html There are live fumaroles high on the mountain, about 800 feet below the summit. You could see the gases venting in the videos taken a few weeks ago at the site of a fatal climbing accident, and the helicopter crash which occurred during the rescue operations. While I knew of the fumaroles, I had never 'seen' them; I was startled by the level of activity. I don't know if this activity level was unusual. See the USGS Cascades Volcano Observatory (CVO) at: http://vulcan.wr.usgs.gov/ Early this May, I talked for several hours with Drs. Rauscher and van Bise who predicted the eruption of Mt St Helens, and many earthquakes over the past 20 years. They said they detected signals from St Helens in October or November of 1979, months before geophysicists were surprised by the early eruptive events. (You can see information about them on my website. Look at the bottom of this post. I will be adding information about their work.) Take care, Bob Fryer >What's everyone's guess about Mt. Hood in Oregon or have you been >following? There have been a remarkable number of quakes near the >cone. Yesterday morning's swarm started with a M4.8 bang and it was >followed by at least forty aftershocks. > >Is she telling us something? > >Kareem -- earthquake WARNING research Animals, People, Scientific Evidence www.earthquakewarning.org __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Integration and Winquake From: John Hernlund hernlund@............ Date: Mon, 01 Jul 2002 16:18:23 -0700 In practice, the FFT can be used to very easily obtain the integral or derivative of a time series (i.e. division or multiplication of all spectral points by i*frequency respectively). Since this is already built into Winquake, this would be the most efficient method, and is the one I always assumed was being used by Winquake. In this case there is no finite integration step, since the FFT is a sinusoidal fit, which is then played with. Randall Pratt wrote: >Arie, > >I don't have an answer but I have wondered about this also. I've considered >summing as you thought and also the possibility of maybe trapazoidal areas >with several points. Another question I have is how the result can begin at >other than zero displacement with a velocity sensor and zero time at file >start? I wonder if the algorithym starts in the middle or from some average >point and works to the ends? > >Randy > >----- Original Message ----- >From: "Arie Verveer" >To: >Sent: Tuesday, June 25, 2002 6:28 AM >Subject: Integration and Winquake > > > > >>Hi, Just a small question; When integrating data with Winquake >>does anyone now the integration period.? I would assume the integrated >>value is the sum of the y values times 1/ ( sample rate ) over the length >>of the integration period? . I'm probably wrong, any idea's. >> >> >>Cheers >> >>Arie >>__________________________________________________________ >> >>Public Seismic Network Mailing List (PSN-L) >> >>To leave this list email PSN-L-REQUEST@.............. with >>the body of the message (first line only): unsubscribe >>See http://www.seismicnet.com/maillist.html for more information. >> >> >> > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > > In practice, the FFT can be used to very easily obtain the integral or derivative of a time series (i.e. division or multiplication of all spectral points by i*frequency respectively). Since this is already built into Winquake, this would be the most efficient method, and is the one I always assumed was being used by Winquake. In this case there is no finite integration step, since the FFT is a sinusoidal fit, which is then played with.

Randall Pratt wrote:
Arie,

I don't have an answer but I have wondered about this also.  I've considered
summing as you thought and also the possibility of maybe trapazoidal areas
with several points.  Another question I have is how the result can begin at
other than zero displacement with a velocity sensor and zero time at file
start?  I wonder if the algorithym starts in the middle or from some average
point and works to the ends?

Randy

----- Original Message -----
From: "Arie Verveer" <ajbv@............>
To: <PSN-L@..............>
Sent: Tuesday, June 25, 2002 6:28 AM
Subject: Integration and Winquake


  
Hi, Just a small question;  When integrating data with Winquake
does anyone now the integration period.? I would assume the integrated
value is the sum of the y values times 1/ ( sample rate ) over the length
of the integration period? . I'm probably wrong, any idea's.


Cheers

Arie
__________________________________________________________

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 for more information.

    

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Subject: Re: Mount Hood...
From: John Hernlund  hernlund@............ 
Date: Mon, 01 Jul 2002 16:29:27 -0700

It would be interesting to see if there has been any of the following 
trends:

- A shallowing of seismic activity over time, indicated upward migration 
of a magma body...
- Small topographic changes localized around the cone's immediate 
vicinity...
- Changes in gas flow and chemistry showing fresh movement and degassing...

 From what I have heard, none of these seems to be happening, but you 
never know with these things! There are some people using a remote 
sensing technique called InSAR which is a space-based radar 
interferogram of the ground which can detect very small changes in the 
shape of the ground. This type of thing has enormous potential for 
assessing volcanic risk since a change in shape over a broad region can 
be roughly inverted to find the depth of the magma expansion or 
disturbance using the theory of elasticity. Pretty cool stuff.

kArEEm wrote:

> What's everyone's guess about Mt. Hood in Oregon or have you been 
> following? There have been a remarkable number of quakes near the 
> cone. Yesterday morning's swarm started with a M4.8 bang and it was 
> followed by at least forty aftershocks.
>  
> Is she telling us something?
>  
> USGS Info 
>  
> Kareem





  
  


It would be interesting to see if there has been any of the following trends:

- A shallowing of seismic activity over time, indicated upward migration of a magma body...
- Small topographic changes localized around the cone's immediate vicinity...
- Changes in gas flow and chemistry showing fresh movement and degassing...

From what I have heard, none of these seems to be happening, but you never know with these things! There are some people using a remote sensing technique called InSAR which is a space-based radar interferogram of the ground which can detect very small changes in the shape of the ground. This type of thing has enormous potential for assessing volcanic risk since a change in shape over a broad region can be roughly inverted to find the depth of the magma expansion or disturbance using the theory of elasticity. Pretty cool stuff.

kArEEm wrote:
Message
What's everyone's guess about Mt. Hood in Oregon or have you been following? There have been a remarkable number of quakes near the cone. Yesterday morning's swarm started with a M4.8 bang and it was followed by at least forty aftershocks.
 
Is she telling us something?
 
 
Kareem

Subject: Mount Hood Seismicity From: DGentry509@....... Date: Mon, 1 Jul 2002 21:21:40 EDT Click here: Mount Hood Seismicity This activity has a few reports that are deeper than the 1999 swarm. Like she's clearing her throat. Don Gentry Click here: Mount Hood Seismicity This activity has a few reports that are deeper than the 1999 swarm. Like she's clearing her throat.

Don Gentry
Subject: Re: Mount Hood Seismicity From: earth@........... Date: Mon, 1 Jul 2002 20:14:04 -0700 (PDT) This activity has a few reports that > are > deeper than the 1999 swarm. Like she's clearing her throat. > > Don Gentry Is it traditional to call all volcanos--shes'? I have often wondered... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mount Hood Seismicity From: earth@........... Date: Mon, 1 Jul 2002 20:13:33 -0700 (PDT) This activity has a few reports that > are > deeper than the 1999 swarm. Like she's clearing her throat. > > Don Gentry Is it traditional to call all volcanos--shes'? I have often wondered... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mount Hood... From: Bob Fryer bfryer@............ Date: Tue, 2 Jul 2002 04:46:50 -0700 John, I haven't heard of any such activities for Mt Hood; but last year (?) the discovery of a large bulge near South Sister (one of Three Sisters, Oregon Cascades volcanoes) caused quite a stir. I do have a several dozen Mt Hood GIFs from Univ of Wash back to Jan. 99 showing the various events shifting around, some near the fumaroles. Also have some lists if anyone wants them. Bob Fryer >It would be interesting to see if there has been any of the following trends: > >- A shallowing of seismic activity over time, indicated upward >migration of a magma body... >- Small topographic changes localized around the cone's immediate vicinity... >- Changes in gas flow and chemistry showing fresh movement and degassing... > >From what I have heard, none of these seems to be happening, but you >never know with these things! There are some people using a remote >sensing technique called InSAR which is a space-based radar >interferogram of the ground which can detect very small changes in >the shape of the ground. This type of thing has enormous potential >for assessing volcanic risk since a change in shape over a broad >region can be roughly inverted to find the depth of the magma >expansion or disturbance using the theory of elasticity. Pretty cool >stuff. > >kArEEm wrote: > >>Message >>What's everyone's guess about Mt. Hood in Oregon or have you been >>following? There have been a remarkable number of quakes near the >>cone. Yesterday morning's swarm started with a M4.8 bang and it was >>followed by at least forty aftershocks. >> >>Is she telling us something? -- earthquake WARNING research Animals, People, Scientific Evidence www.earthquakewarning.org __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Filter From: "Liberio Rossi" liberossi@......... Date: Thu, 4 Jul 2002 06:06:05 +0200 Dear Larry, Just to inform you that I am facing a problem: When I push the button " F " in order to insert the filter, the dialog = box shows a label where I read: You esecuted a wrong action. please, contact your = supplier. I am using winquake 2.8.9. Can you help me. Have my best regards Liberio Rossi liberossi@.........
Dear Larry,
Just to inform you that I am facing a=20 problem:
When I push the button " F " = in=20 order to insert the filter,  the dialog box shows a = label
where I read: You esecuted a wrong = action. please,=20 contact your supplier.
 
I am using winquake 2.8.9.
 
Can you help me.
 
Have my best regards
Liberio Rossi
liberossi@.........
<= /BODY> Subject: Re: Filter From: "Larry Cochrane" cochrane@.............. Date: Wed, 3 Jul 2002 23:24:30 -0700 Hello Liberio, What dialog box are you in when you press the "F" key? If you let me = know the full title of the dialog box it will help me debug the problem. Regards, -Larry ----- Original Message -----=20 From: Liberio Rossi=20 To: psn-l@................. Sent: Wednesday, July 03, 2002 9:06 PM Subject: Filter Dear Larry, Just to inform you that I am facing a problem: When I push the button " F " in order to insert the filter, the = dialog box shows a label where I read: You esecuted a wrong action. please, contact your = supplier. I am using winquake 2.8.9. Can you help me. Have my best regards Liberio Rossi liberossi@libero.it
Hello Liberio,
 
What dialog box are you in when you = press the "F"=20 key? If you let me know the full title of the dialog box it will help me = debug=20 the problem.
 
Regards,
-Larry
----- Original Message -----
From:=20 Liberio=20 Rossi
Sent: Wednesday, July 03, 2002 = 9:06=20 PM
Subject: Filter

Dear Larry,
Just to inform you that I am facing a = problem:
When I push the button " F " = in=20 order to insert the filter,  the dialog box shows a = label
where I read: You esecuted a wrong = action.=20 please, contact your supplier.
 
I am using winquake = 2.8.9.
 
Can you help me.
 
Have my best regards
Liberio Rossi
liberossi@.........
<= /BLOCKQUOTE> Subject: R: Filter From: "Liberio Rossi" liberossi@......... Date: Thu, 4 Jul 2002 09:11:33 +0200 Thanks Larry. The F I sed appear in the bar placed over the box i said before together = an "I" and all commands to use for zumming etc. it is enough to understanding what I means. Thank Larry Liberio Rossi liberossi@......... ----- Original Message -----=20 From: Larry Cochrane=20 To: psn-l@................. Sent: Thursday, July 04, 2002 8:24 AM Subject: Re: Filter Hello Liberio, =20 What dialog box are you in when you press the "F" key? If you let me = know the full title of the dialog box it will help me debug the problem. =20 Regards, -Larry ----- Original Message -----=20 From: Liberio Rossi=20 To: psn-l@................. Sent: Wednesday, July 03, 2002 9:06 PM Subject: Filter Dear Larry, Just to inform you that I am facing a problem: When I push the button " F " in order to insert the filter, the = dialog box shows a label where I read: You esecuted a wrong action. please, contact your = supplier. I am using winquake 2.8.9. Can you help me. Have my best regards Liberio Rossi liberossi@.........
Thanks Larry.
The F I sed appear in the bar placed = over the box i=20 said before together an "I"  and all commands to use for zumming=20 etc.
 
it is enough to understanding what I=20 means.
Thank Larry
Liberio Rossi
liberossi@.........
 
----- Original Message -----
From:=20 Larry=20 Cochrane
Sent: Thursday, July 04, 2002 = 8:24=20 AM
Subject: Re: Filter

Hello Liberio,
 
What dialog box are you in when you = press the "F"=20 key? If you let me know the full title of the dialog box it will help = me debug=20 the problem.
 
Regards,
-Larry
----- Original Message -----
From:=20 Liberio=20 Rossi
To: psn-l@..............
Sent: Wednesday, July 03, = 2002 9:06=20 PM
Subject: Filter

Dear Larry,
Just to inform you that I am facing = a=20 problem:
When I push the button " F = "=20 in order to insert the filter,  the dialog box shows a = label
where I read: You esecuted a wrong = action.=20 please, contact your supplier.
 
I am using winquake = 2.8.9.
 
Can you help me.
 
Have my best regards
Liberio Rossi
liberossi@.........
<= /BLOCKQUOTE>
Subject: rFilter data From: "Liberio Rossi" liberossi@......... Date: Thu, 4 Jul 2002 11:19:34 +0200 Hi Larry, The dialog box I mean is the one where we can see all the data = concerning files. On the first linewe can see " OPEN FILE" File or files name Directory an empti space is ready to receive all the file youreceived. Under white space there are these buttons: Open File Add Event Report Change Directory Send e-mail message Convert Reply UPdate Delete Help. Well, Larry, over this dia Boxthere are these titles: EVENT WINDOW - MENU and Tool Bar On the tool bar there are the the following signs: Diskette a button with eq over, the simbol of a map A PS button a button = with "loc" "md" "R/T , " FFT" another one button with " fft " (smaller characters) " I " " F = ", one containin two pages , one handling 4 vertical bars, other two = buttons and the button we press to see a MAP Last one is "rst". Larry, I beg you pardon for all the noise I given. Hope now you will understand. Have a good day and thanks for very appreciated help. Liberio liberossi@.........
Hi Larry,
 
The dialog box I mean is the one where = we can see=20 all the data concerning files.
On the first linewe can see " OPEN=20 FILE"
File or files=20 name           &nb= sp;           &nbs= p;            = ;        =20 Directory
 
an empti space is ready to = receive  all the=20 file youreceived.
Under white space there are these=20 buttons:
 
Open File      = Add Event=20 Report  Change Directory   Send e-mail = message
Convert  =20 Reply       = UPdate     =20 Delete       Help.
 
Well, Larry, over this dia Boxthere are = these=20 titles:
 
EVENT WINDOW - MENU and Tool = Bar
On the tool bar there are the the = following=20 signs:
 
Diskette a button with eq over, the = simbol of a map=20 A PS button a button with "loc"   "md"  "R/T  = , "=20 FFT"
another one button with " fft " = (smaller=20 characters)      " I "     = " F=20 ",  one containin two pages , one handling 4 vertical bars, other = two=20 buttons and the button we press to see a MAP   Last one is=20 "rst".
 
Larry, I beg you pardon for all the = noise I=20 given.
Hope now you will = understand.
Have a good day and thanks for very = appreciated=20 help.
Liberio
liberossi@.........
 
 
 
 
 
 
 
Subject: Mount Hood From: John & Jan johnjan@........ Date: Thu, 04 Jul 2002 07:07:46 -0600 >To: Assistant Secretary for Water and Science > Chief of Staff > Director, Office of Communications > >From: Barbara Wainman, Chief, Office of Communications, USGS > >Subject: USGS Weekly Highlights, July 1-5, 2002 > >I. Departmental/Bureau News >A. Upcoming > >B. Current >Record Earthquake at Mount Hood: On June 29, the Mount Hood, Ore., area >was shaken by a magnitude 4.5 earthquake located 3 miles below the south >flank of the mountain. As of July 2, there have been hundreds of >aftershocks, including several felt events. During the past 22 years of >monitoring by the USGS and the Pacific Northwest Seismograph Network, the >largest event detected prior to June 29 was M3.5. At the present time, the >events appear to be a typical mainshock/aftershock sequence of a tectonic >earthquake. Scientists have installed additional seismometers in the field >and are watching events closely. USGS will also monitor crustal movement >and gas emissions. (Willie Scott, Vancouver, WA, 360-993-8942) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: 24btis A/D converter 6 seismology From: "Francois" furansowa@........... Date: Thu, 4 Jul 2002 15:17:22 +0200 Hello dear all, could someone explain me why you need 24bits AD converters in seismology. Indeed it corresponds to 16.8millions points on a 2g scale, which thus corresponds to a resolution of about 120 nano-g (10^-12g !) Isn't the ambient noise muche higher than this ? thanks in advance for "enlighting" me. Francois ______________________________________________________________________________ ifrance.com, l'email gratuit le plus complet de l'Internet ! vos emails depuis un navigateur, en POP3, sur Minitel, sur le WAP... http://www.ifrance.com/_reloc/email.emailif __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: 24bits A/D converters & seismology From: "Francois" furansowa@........... Date: Thu, 4 Jul 2002 17:22:02 +0200 Hello dear all, could someone explain me why you need 24bits AD converters in seismology. Indeed it corresponds to 16.8millions points on a 2g scale, which thus corresponds to a resolution of about 120 nano-g (10^-12g !) Isn't the ambient noise much higher than this ? thanks in advance for "enlighting" me. Francois ______________________________________________________________________________ ifrance.com, l'email gratuit le plus complet de l'Internet ! vos emails depuis un navigateur, en POP3, sur Minitel, sur le WAP... http://www.ifrance.com/_reloc/email.emailif __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 24bits A/D converters & seismology From: Jim Hannon jmhannon@......... Date: Thu, 04 Jul 2002 11:43:30 -0500 Francios, Most amateur systems work quite well with much less than 24 bits. In fact it is very difficult to build any electronics that will have noise low enough to work with 24 bits of resolution. Of course if you can it is nice to work with as much resolution as possible. It helps with not clipping on very large events or missing very small ones depending on how your system is adjusted. You don't have to adjust the gain of the system as carefully with more bits as you have more room for the signal to fit within the range of the A/D converter. At 05:22 PM 7/4/02 +0200, you wrote: >Hello dear all, > >could someone explain me why you need 24bits AD converters in seismology. > >Indeed it corresponds to 16.8millions points on a 2g scale, which thus >corresponds to a resolution of about 120 nano-g (10^-12g !) >Isn't the ambient noise much higher than this ? > >thanks in advance for "enlighting" me. > >Francois > > >______________________________________________________________________________ >ifrance.com, l'email gratuit le plus complet de l'Internet ! >vos emails depuis un navigateur, en POP3, sur Minitel, sur le WAP... >http://www.ifrance.com/_reloc/email.emailif > Jim Hannon http://www.fmtcs.com/web/jmhannon 42,11.90N,91,39.26W WB0TXL __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 24bits A/D converters & seismology From: "Francois" furansowa@........... Date: Thu, 4 Jul 2002 21:04:09 +0200 Hello Jim, thank you for your answer! Of course I understand that amateur systems do not need a 24bit A/D converter : ) But I am wondering what is the reason why commercial seismometers have a 24bit A/D convertor. How do you explain the need for such a hight sensitivity? (120 nano-g this is so small!) Don't you think that the seismic noise (assuming the eletronic noise is reduced to minimum) is much bigger than hundrerds of nano-g ? Do you think that commercial seismometers really use the full 24bit output of there convertors? won't it be much enough to use 20bits (2 micro-g resolution) ? Francois ----- Original Message ----- From: "Jim Hannon" To: Sent: jeudi, 4. juillet 2002 18:43 Subject: Re: 24bits A/D converters & seismology > Francios, > Most amateur systems work quite well with much less than 24 bits. In fact > it is very difficult to build any electronics that will have noise low > enough to work with 24 bits of resolution. Of course if you can it is nice > to work with as much resolution as possible. It helps with not clipping on > very large events or missing very small ones depending on how your system > is adjusted. You don't have to adjust the gain of the system as carefully > with more bits as you have more room for the signal to fit within the range > of the A/D converter. > > At 05:22 PM 7/4/02 +0200, you wrote: > >Hello dear all, > > > >could someone explain me why you need 24bits AD converters in seismology. > > > >Indeed it corresponds to 16.8millions points on a 2g scale, which thus > >corresponds to a resolution of about 120 nano-g (10^-12g !) > >Isn't the ambient noise much higher than this ? > > > >thanks in advance for "enlighting" me. > > > >Francois > > > > > >___________________________________________________________________________ ___ > >ifrance.com, l'email gratuit le plus complet de l'Internet ! > >vos emails depuis un navigateur, en POP3, sur Minitel, sur le WAP... > >http://www.ifrance.com/_reloc/email.emailif > > > > Jim Hannon > http://www.fmtcs.com/web/jmhannon > 42,11.90N,91,39.26W > WB0TXL > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. ______________________________________________________________________________ ifrance.com, l'email gratuit le plus complet de l'Internet ! vos emails depuis un navigateur, en POP3, sur Minitel, sur le WAP... http://www.ifrance.com/_reloc/email.emailif __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 24bits A/D converters & seismology From: westfall@....... Date: Thu, 04 Jul 2002 14:43:34 -0700 Is it not the case that most commercial seismometers these days are wideband instruments? If so, they may need 24 bits to handle the much larger dynamic range of these instruments. Its possible that 20 bits might be enough, but vendors may have decided to go for the extra 4 bits rather than restrict the range. Considering the price of a commercial instrument, the extra 4 bits probably does not add to the cost of construction sufficiently to warrant changing the price. Its also possible that 24 bits (3 bytes) is preferred, because it slightly simplifies the data processing software. Comments? Ron ----- Original Message ----- From: Francois Date: Thursday, July 4, 2002 12:04 pm Subject: Re: 24bits A/D converters & seismology > Hello Jim, > thank you for your answer! > > Of course I understand that amateur systems do not need a 24bit A/D > converter : ) > > But I am wondering what is the reason why commercial seismometers > have a > 24bit A/D convertor. > How do you explain the need for such a hight sensitivity? (120 > nano-g this > is so small!) > Don't you think that the seismic noise (assuming the eletronic > noise is > reduced to minimum) is much bigger than hundrerds of nano-g ? > Do you think that commercial seismometers really use the full > 24bit output > of there convertors? won't it be much enough to use 20bits (2 > micro-g > resolution) ? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 24bits A/D converters & seismology From: Hammonds hammond@........... Date: Thu, 04 Jul 2002 13:52:15 -0800 Hi all, This is from the ORFEUS website: http://orfeus.knmi.nl/working.groups/wg1/standard.html "The digitizer is a critical part in a VBB seismograph. It must however cover a dynamic range of at least 140 dB, and it must have an excellent linearity and resolution because signals of greatly different amplitude may simultaneously be present in different parts of the VBB seismic band." So, the desire to have high dynamic range recording from broadband seismometers is in part why 24-bit digitizers are used. Bob Hammond Fairbanks, AK http://apsn.awcable.com At 01:43 PM 7/4/2002, you wrote: >Is it not the case that most commercial seismometers these days are >wideband instruments? If so, they may need 24 bits to handle the >much larger dynamic range of these instruments. Its possible that >20 bits might be enough, but vendors may have decided to go for the >extra 4 bits rather than restrict the range. Considering the price >of a commercial instrument, the extra 4 bits probably does not add >to the cost of construction sufficiently to warrant changing the >price. Its also possible that 24 bits (3 bytes) is preferred, >because it slightly simplifies the data processing software. >Comments? > >Ron > >----- Original Message ----- >From: Francois >Date: Thursday, July 4, 2002 12:04 pm >Subject: Re: 24bits A/D converters & seismology > > > Hello Jim, > > thank you for your answer! > > > > Of course I understand that amateur systems do not need a 24bit A/D > > converter : ) > > > > But I am wondering what is the reason why commercial seismometers > > have a > > 24bit A/D convertor. > > How do you explain the need for such a hight sensitivity? (120 > > nano-g this > > is so small!) > > Don't you think that the seismic noise (assuming the eletronic > > noise is > > reduced to minimum) is much bigger than hundrerds of nano-g ? > > Do you think that commercial seismometers really use the full > > 24bit output > > of there convertors? won't it be much enough to use 20bits (2 > > micro-g > > resolution) ? > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 24bits A/D converter 6 seismology From: ChrisAtUpw@....... Date: Thu, 4 Jul 2002 18:10:23 EDT In a message dated 04/07/02, furansowa@........... writes: > could someone explain me why you need 24bits AD converters in seismology. > Indeed it corresponds to 16.8millions points on a 2g scale, which thus > corresponds to a resolution of about 120 nano-g (10^-12g !) > Hi Francois, Some, but not all the '24 bit' A/Ds do give 24 bits if you take samples slowly enough. The range for 'normal' sampling rates may be 18 to 22 bits. They will only effectively handle one channel / sensor at a time - the settling time on channel change tends to be rather long. The idea is that you don't then need amplifiers for your sensors and the one range will handle all possible signal levels, so you read a Geophone etc directly into the A/D. However, it may be more than a bit difficult to sense signals less than 100 nano Volts. I do not know what is done about the several micro volts of thermo-electric potentials that you will inevitably get, though. These and many other technical issues are described in detail in a 5.6 MB file at http://www.ifjf.uib.no/seismo/SOFTWARE/OTHER/instrument.pdf This looks a very good 'book' and well worth keeping as a reference. Regards, Chris Chapman In a message dated 04/07/02, furansowa@........... writes:

could someone explain me why you need 24bits AD converters in seismology.
Indeed it corresponds to 16.8millions points on a 2g scale, which thus corresponds to a resolution of about 120 nano-g (10^ -12g !)
Isn't the ambient noise much higher than this ?


Hi Francois,

      Some, but not all the '24 bit' A/Ds do give 24 bits if you take samples slowly enough. The range for 'normal' sampling rates may be 18 to 22 bits. They will only effectively handle one channel / sensor at a time - the settling time on channel change tends to be rather long.
      The idea is that you don't then need amplifiers for your sensors and the one range wil l handle all possible signal levels, so you read a Geophone etc directly into the A/D. However, it may be more than a bit diffi cult to sense signals less than 100 nano Volts. I do not know what is done about the several micro volts of thermo-electric pot entials that you will inevitably get, though.
      These and many other technical issues are described in detail in a 5.6 MB file at http ://www.ifjf.uib.no/seismo/SOFTWARE/OTHER/instrument.pdf
      This looks a very good 'book' and well worth keeping as a reference.

      Regards,

      Chris Chapman
Subject: Re: 24bits A/D converters & seismology From: Jim ODonnell jimo17@........ Date: Thu, 4 Jul 2002 17:05:07 -0700 In a message dated 04/07/02, furansowa@........... writes: could someone explain me why you need 24bits AD converters in seismology. Indeed it corresponds to 16.8millions points on a 2g scale, which thus corresponds to a resolution of about 120 nano-g (10^-12g !) Isn't the ambient noise much higher than this ? Hi Francois, Looks like you got our attention- Here is my shot at why! Comments on why 24 bit digitizers are needed. Even with 24 bit digitizers and 140 db BB seismometers, the seismographs go off scale. Look at the records for any large EQ M>7 and you will see the seismographs go off scale if they are within a few hundred km. of the epicenter; Taiwan and Hector Mine come to mind. The solution is SM seismographs which clip ~2g, I believe the largest acceleration recorded are ~1.7 g from the Northridge M6.7 in 1994. Note Larry Cochrane’s PSN-accelerometer chip uses a Gain Ranging scheme to record High and Low gain, utilizing the inexpensive 16 bit A/D, to stay on scale for the big one (clips ~2g); but is still able to record some smaller events (clips ~70mg) which depends on the inherent noise of the chips, which are only going to improve. See http://psn.quake.net/psnaccel/ Digitizer dynamic range ~1.0e07 10 bit=1024 or ~1.0 e03, 20 bit ~1.0 e06, and 24 bit ~16 e06 ~1.0e07 Seismometer dynamic range for Good BB 1.0e07 (Best Guess for now) 140 db, 140/20 =7 orders of magnitude that is 1.0e07 Earthquake amplitude range: 1.0 e10 From M-1 to M8 we cover ~10 orders of amplitude velocity variation for periods of 0.01 to 10 Hz. (See Chuck Ammon’s class notes from SLU for plot on seismic ground amplitudes for earthquakes and comments, given below: http://www.eas.slu.edu/People/CJAmmon/HTML/Classes/IntroQuakes/Notes/seis mometers.html Seismic Signals The range of ground motions that are interesting to seismologists is very large because the process of earth deformation occurs at many different rates and scales. The amplitude range of interesting signals in earthquake studies as a function of frequency compared with a similar range of physical dimensions of some common items. Since I am comparing the "spectral" amplitude as a function of frequency with physical dimensions of the common items, the analogy is not perfect, but the range of variation in size is well represented. "D" represents the distance from the earthquake. We usually specify large distances over Earth's surface in units of degrees and 1 degree = 111.19 km. The large range of amplitudes we are interested in exists because we are interested in all the processes occurring in Earth, from small rock fractures that form in mines to the great earthquakes that occur each year. The amount of energy released by these different processes is enormous, and the large range of interesting amplitudes reflects this. Jim O'Donnell/ UNLV
In a message dated 04/07/02, furansowa@= ifrance.com=20 writes:

could someone explain me why you need 24bits AD converters in= =20 seismology.
Indeed it corresponds to 16.8millions points on a 2g = scale,=20 which thus corresponds to a resolution of about 120 nano-g (10^-12g !)=20
Isn't the ambient noise much higher than this ?
Hi Francois,

Looks like you got our = attention- Here=20 is my shot at why!

Comments on why 24 bit = digitizers are=20 needed.

Even with 24 bit digitizers and = 140 db BB=20 seismometers, the seismographs go off scale.  Look at the records for any large= EQ=20 M>7 and you will see the seismographs go off scale if they are within a = few=20 hundred km. of the epicenter; Taiwan and Hector Mine come to mind.  The solution is SM seismographs = which=20 clip ~2g, I believe the largest acceleration recorded are ~1.7 g from the=20 Northridge M6.7 in 1994.  = Note Larry=20 Cochrane=92s PSN-accelerometer chip uses a Gain Ranging scheme to record = High and=20 Low gain, utilizing the inexpensive 16 bit A/D, to stay on scale for the = big one=20 (clips ~2g); but is still able to record some smaller events (clips ~70mg) = which=20 depends on the inherent noise of the chips, which are only going to improve= ..=20

See http://psn.quake.net/psnaccel/<= /P>

 

 

Digitizer dynamic = range=20 ~1.0e07

10 bit=3D1024 or ~1.0 e03, 20 = bit ~1.0 e06,=20 and 24 bit ~16 e06  ~1.= 0e07=20

 

Seismometer dynamic range for = Good BB=20 1.0e07 (Best Guess for now)

140 db, 140/20 =3D7 orders of = magnitude=20 that is 1.0e07

 

Earthquake amplitude  range: 1.0=20 e10

From M-1 to M8 we cover ~10 = orders of=20 amplitude velocity variation for periods of 0.01 to 10 Hz. (See Chuck= =20 Ammon=92s class notes from SLU for plot on seismic ground amplitudes for= =20 earthquakes and comments, given below:

http://www.eas.slu.edu/People/CJAmmon/HTML/Classes= /IntroQuakes/Notes/seismometers.html

Seismic Signals

The range of ground motions that are interesting to seismologists is = very=20 large because the process of earth deformation occurs at many different = rates=20 and scales.

The= =20 amplitude range of interesting signals in earthquake studies as a = function=20 of frequency compared with a similar range of physical dimensions of = some=20 common items. Since I am comparing the "spectral" amplitude as a = function=20 of frequency with physical dimensions of the common items, the = analogy is=20 not perfect, but the range of variation in size is well=20 represented. "D" represents the distance from the earthquake. We = usually=20 specify large distances over Earth's surface in units of degrees and = 1=20 degree =3D 111.19 km.

The large range of amplitudes we are interested in exists because we are= =20 interested in all the processes occurring in Earth, from small rock = fractures=20 that form in mines to the great earthquakes that occur each year. The = amount of=20 energy released by these different processes is enormous, and the large = range of=20 interesting amplitudes reflects this.

Jim O'Donnell/ UNLV

Subject: =?iso-8859-1?Q?Water_rocket?= From: "=?iso-8859-1?Q?jean-pierre-laine@.............. jean-pierre-laine@laposte.net Date: Fri, 5 Jul 2002 12:42:32 +0200 hello go to perso.wanadoo.fr/fusee bye Acc=E9dez au courrier =E9lectronique de La Poste : www.laposte.net ; 3615 LAPOSTENET (0,13 =80/mn) ; t=E9l : 08 92 68 13 50 (0, 34=80/mn)" __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: =?iso-8859-1?Q?Water_rocket?= From: "=?iso-8859-1?Q?jean-pierre-laine@.............. jean-pierre-laine@laposte.net Date: Fri, 5 Jul 2002 12:42:32 +0200 hello go to perso.wanadoo.fr/fusee bye Acc=E9dez au courrier =E9lectronique de La Poste : www.laposte.net ; 3615 LAPOSTENET (0,13 =80/mn) ; t=E9l : 08 92 68 13 50 (0, 34=80/mn)" __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Lehman construction question From: "Jim Martin" jimdmartin@................ Date: Sun, 7 Jul 2002 16:30:14 -0500 I am a new member to this list, and am also building my first Lehman seis. I have a couple of questions: 1). I am using a 1/2" steel threaded rod for the boom. Will this be ok, or should the boom be of non-ferrous material? 2). Is there a recommended distance between the boom pivot point and the boom support wire attachment point? I know that initially the boom wire pivot should lead the boom pivot by about 1cm, but I am just curious if there is a recommended max distance from boom to upper crossarm. Thanks to everyone.... Jim D. Martin Fort Wayne, Indiana __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: 24bits A/D converters & seismology From: "Barry" gbl@....... Date: Mon, 8 Jul 2002 20:16:22 -0700 Hi Jim et al I like the auto-variable gain idea. I have in the past run a 12 = bit A/D with a variable gain (1- 1024). The triggering routine and how = you store the data gets a little complicated, but it works pretty well. = There can be a slight zero shift when the computer changes gains. I used = a Maxim 16 position switch with a resistor ladder. It's best run running = at a reasonable gain and if an event occurs, then the gain is reduced by = multiples of two to stay on scale. One can store the gain setting for = each data point at the lower bit area. 16 bit with variable gain is what = I'm shooting for. =20 Regards Barry
Hi Jim et al
      I like = the=20 auto-variable gain idea. I have in the past run a 12 bit A/D with a = variable=20 gain (1- 1024). The triggering routine and how you store the data gets a = little=20 complicated, but it works pretty well. There can be a slight zero shift = when the=20 computer changes gains. I used a Maxim 16 position switch with a = resistor=20 ladder. It's best run running at a reasonable gain and if an event = occurs, then=20 the gain is reduced by multiples of two to stay on scale. One can = store the=20 gain setting for each data point at the lower bit area. 16 bit with = variable gain is what I'm shooting for. 
Regards
Barry
 
 
Subject: Lowpass Band Filter From: "Euro Atencio" eatencio@.......... Date: Mon, 15 Jul 2002 17:24:19 -0500 Hi Larry or anyone with Larry's Filter board!! I don't know why I'm not having any lowpass band filter. Hope I could hear suggestions; Euro
Hi Larry or anyone with Larry's Filter=20 board!!
 
I don't know why I'm not having any = lowpass band=20 filter.
 
Hope I could hear = suggestions;
 
Euro
Subject: LEHMAN From: "Euro Atencio" eatencio@.......... Date: Tue, 16 Jul 2002 06:17:05 -0500 I am localized in Orlando, Florida and I built a Lehman that it is seam = to be that my sensor has a resonance of ~8 to 10 Hz, so the lowpass band = filter can not work properly; if there is someone near by or could help = me with this please let me know. Best Regards; Euro
I am localized in Orlando, Florida and = I built=20 a Lehman that it  is seam to be that my sensor has a resonance = of ~8=20 to 10 Hz, so the lowpass band filter can not work properly; if = there is=20 someone near by or could help me with this please let me = know.
 
Best Regards;
 
Euro
Subject: FW: [EDIS] EQ 3 14 SANTA CLARA COUNTY [News: San Francisco Bay] From: jim_oberhofer@........... Date: Wed, 17 Jul 2002 14:57:22 -0600 FYI... Jim O, Cupertino, CA -----Original Message----- From: EDIS Email Service [mailto:edismail@............. Sent: Wednesday, July 17, 2002 12:32 PM To: EDIS-by-Email@............ Subject: [EDIS] EQ 3 14 SANTA CLARA COUNTY [News: San Francisco Bay] PRELIMINARY EARTHQUAKE REPORT Rapid Earthquake Location Service U.S. Geological Survey, Menlo Park, California U.C. Berkeley Seismological Laboratory, Berkeley, California Version 2: Updates lower and earlier versions of this earthquake report A MINOR EARTHQUAKE OCCURRED AT 12:07 PM PDT Wednesday, Jul 17, 2002. THE MAGNITUDE 3.1 (ML) EVENT IS LOCATED 11 MILES N OF MORGAN HILL, CA THE HYPOCENTRAL DEPTH IS 4.0 MILES. This event has been reviewed by the USGS on-duty seismologist. PRINCIPAL EARTHQUAKE PARAMETERS _______________________________ Magnitude : 3.14 ML Event Date & Time : 07/17/2002 12:07:42 PM PDT 07/17/2002 19:07:42 UTC Location : 37.2897 N, 121.6658 W : (37 deg. 17.38 min. N, 121 deg. 39.95 min. W) Depth : 6.5 km. deep ( 4.0 miles) Location Quality : Excellent 18 km ( 11 miles) N (356 degrees) of Morgan Hill, CA 21 km ( 13 miles) ESE (105 degrees) of San Jose City Hall, CA 23 km ( 14 miles) NNW (347 degrees) of San Martin, CA 25 km ( 16 miles) E ( 89 degrees) of Campbell, CA 26 km ( 16 miles) SE (126 degrees) of Milpitas, CA ADDITIONAL EARTHQUAKE PARAMETERS ________________________________ number of phases : 149 rms misfit : 0.07 seconds horizontal location error : 0.1 km vertical location error : 0.3 km maximum azimuthal gap : 50 degrees distance to nearest station : 3. km event ID: 51120424 EDIS-07-17-02 1223 PDT --------------------------------------------------------- To update or terminate your subscription to this email service visit our webpage at http://www.incident.com/edismail.html. Please DO NOT reply to this message: replies may be treated as errors and result in your subscription being deleted. If you have trouble with the Web form, or for other queries, email . (But for faster service try the Web method first!) EDIS is operated by the Governor's Office of Emergency Services, State of California. This email relay service is offered by incident.com on a non-commercial, subscription-only basis. Because of the complexity of this system and its dependence on other systems, we cannot be responsible for delays or failures in forwarding or transmission. --------------------------------------------------------- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: FS: ISA A/D board From: Greg geo@........... Date: Thu, 18 Jul 2002 13:21:56 -0700 I got permission to post this. I'm entertaining offers on my ISA A/D board. It has the 16 bit Burr-Brown chip on it. Larry made it. I can put a picture on a webserver, but it's just like the pics on Larry's site. http://psn.quake.net/atod.html It looks like the Rev 2 board. I have the WWV circuit, but not the thermally isolated timer what-cha-ma-jigger (goes in the big open space on the end of the board). It's still $245 new? I have a "D" shell connector (2 wires soldered) and floppies (SDR and 32 bit Winquake) for it also. Oh yeah, it works fine. You might want to check to see if you have an open ISA slot and a free IRQ before you decide you want it. If you really want, I can sell you a computer to go along with it. I have a spare P133 system that I can install it in. It has 64 MB EDO RAM, NE2000 network card, CDROM and a 2.5 GB hard drive. A MSDOS license is up to you to get. No monitor. Shipping will probably be pricey though. I took it out of the computer and disconnected everything. Send offers straight to me. Not to the list. I can give you my ebay account name if you want to look at my feedback. It's 16 positive, 0 neutral and 0 negative. Thanks, Greg __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: AS-1 Seismograph for sale From: "angel@......... angel@chiriqui.com Date: Sat, 20 Jul 2002 19:42:20 -0500 Hello Everyone, I have an AS-1 Seismograph for sale for $275.00 I paid $425.. This is complete turnkey system. It includes everything, power supply, electronics and seismograph. Just plug it and ready to go. Uses Amaseis software. (Also the AS-1 software) http://www.eas.purdue.edu/~braile/edumod/as1mag/as1mag.htm I can take PayPal Best regards, angel mailto:angel@.............. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: New WinSDR release From: "Larry Cochrane" cochrane@.............. Date: Sat, 27 Jul 2002 16:13:20 -0700 All, I have a new WinSDR release available on my web site. You can download it from here http://www.seismicnet.com/winsdr/. The release version number is 2.0.7. There are two new features in WinSDR. The first one is the ability to filter the data used to produce the GIF images. In the GIF Settings dialog box you will see a new group box called Filter Control. You can enable or display lowpass and highpass filters, set the cutoff frequency and the number of poles for each channel using the controls in this group box. A note about digital filtering. The process of digital filtering can take a lot of CPU time to filter the data used to produce the GIF images. You need to make sure your system is fast enough to had the extra load on the system when you filter the GIF images. One way of monitoring how well your system is running, is to open the Status Viewer (use the View / Status Viewer menu items to open this dialog box) in WinSDR and keep an eye on the Max Input Queue number on the bottom right hand side of the dialog box. The first number is the maximum number of RS-232 input characters seen in the input queue. The second number is the size of the queue. This is currently set to 32678. If the system is very busy doing other things, like creating GIF images, then reading the input data, the input max input queue number will get larger. If WinSDR cannot keep up with the data coming from the A/D board, the input queue will fill up to 32768 and you will start seeing data errors do to the loss of data. If this happens, you either need to turn off filtering or get a faster system. The other thing new with WinSDR is the support for a new GPS receiver. I was looking around for other GPS options other then the Motorola ONCORE receiver and came across the Garmin GPS 16 Sensor. This receiver has the antenna built in and it has the all important 1 pulse per second output signal needed for accurate time keeping. More info on the receiver can be found here http://www.garmin.com/products/gps16/index.html. This is a very nice receiver. Since the receiver and antenna are mounted together, extending the data cable length between your datalogger system and the receiver can be done with a standard 9-pin to 9-pin RS-232 cable. I have tried 50 feet (~16 me) of cable without any problems. The receivers I have been getting run on ~5 VDC, higher voltage models are also available. What I have been doing is adding two jumpers on my serial output A/D board that supply +5 volts to the receiver and a ground signal through the RS-232 cable. Since the receiver inputs/outputs standard RS-232 signal levels (except the 1 PPS signal, it's 0 to 5 v) there is no need for a interface board like what's needed for the ONCORE receiver. To use this new GPS receiver you must upgrade your A/D board firmware to version 2.0. The new firmware version is included in the install package. In the System Settings dialog box in WinSDR you will see a new Time Reference Type called GPS Garmin. If you are using the Oncore receiver, make sure you select the GPS ONCORE item. An adapter is needed to covert the RJ45 8 pin connector to a 9-pin RS-232 connector. I have information on this page on how to do this http://www.seismicnet.com/winsdr/gps.html. The Garmin GPS 16 also supports a new differential GPS system called WAAS. Currently it's only available here in the States. More info on WAAS can be found on the Garmin site. If the receiver can see one of the two WAAS geostationary satellites, the position information can be improved to less the 5 meters. The WAAS signal is not needed for accurate time keeping. That's it.... Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Economical High Quality Magnets From: "Connie and Jim Lehman" lehmancj@........... Date: Fri, 2 Aug 2002 10:05:32 -0400 It was brought to my attention recently a good source of magnets for = coil pickup or damping purposes are to be found in discarded microwave = units. It takes a bit of digging, but within the klystron or similar = box within, in most models there is a pair of strong cylindrical magnets = for the taking. Good digging, J. = Lehman, Harrisonburg, VA.
It was brought to my = attention recently=20 a good source of magnets for coil pickup or damping purposes are to be = found in=20 discarded microwave units.  It takes a bit of digging, but within = the=20 klystron or similar box within, in most models there is a pair of strong = cylindrical magnets for the taking.
          &nbs= p;            = ;            =             &= nbsp;=20 Good digging,  J. Lehman,  Harrisonburg,=20 VA.
Subject: Re: Economical High Quality Magnets From: ChrisAtUpw@....... Date: Fri, 2 Aug 2002 17:45:48 EDT In a message dated 02/08/02, lehmancj@........... writes: > It was brought to my attention recently a good source of magnets for coil > pickup or damping purposes are to be found in discarded microwave units. These magnetron magnets are fine for coil pickups, but the field is a bit low and the gap rather too wide for efficient damping. For damping magnets, I suggest going to Forcefield at http://www.wondermagnet.com/dev/magnets.html and getting a pair of #21's at $4.20 each. Type #39 at $12.50 each are even stronger. A sheet of 1/8" copper in the gap feels like it is moving in thick treacle! Type #41 at $1.75 and pairs of Types # 2 at $2.00, or #42 at $2.50 mounted on mild steel backing plates will give very good signals from coils of ~1" dia. These magnets have a N and a S pole on each 'wing' of the face and a coil should be mounted centrally over the face. Regards, Chris Chapman In a message dated 02/08/02, lehmancj@........... writes:

It was brought to my attention recently a good source of magnets for coil pickup or damping purposes are to be found in discarded mic rowave units.  


      These magnetron magnets are fine for coil pickups, but the field is a bit low and the gap rather too wide for efficient damping.
      For damping magnets, I suggest going to Forcefield at http://www.wondermagnet.com/dev/ magnets.html and getting a pair of #21's at $4.20 each. Type #39 at $12.50 each are even stronger. A sheet of 1/8" copper in th e gap feels like it is moving in thick treacle!

      Type #41 at $1.75 and pairs of Types # 2 at $2.00, or #42 at $2.50 mounted on mild ste el backing plates will give very good signals from coils of ~1" dia. These magnets have a N and a S pole on each 'wing' of the face and a coil should be mounted centrally over the face.

      Regards,

      Chris Chapman
Subject: Re: Economical High Quality Magnets From: CapAAVSO@....... Date: Sat, 3 Aug 2002 08:58:10 EDT In a message dated 8/2/02 10:46:13 PM GMT Daylight Time, ChrisAtUpw@....... writes: > For damping magnets, I suggest going to Forcefield at > http://www.wondermagnet.com/dev/magnets.html and getting a pair of #21's at > $4.20 each. Type #39 at $12.50 each are even stronger. A sheet of 1/8" > copper in the gap feels like it is moving in thick treacle! Hi Chris, The best I can find is 1/32 thick copper sheet and as a damping magnet it moves more like it is in very watered down treacle. If I stacked four of these would I get the same damping effect as if I used a 1/8 thick plate? Cap (Casper Hossfield) In a message dated 8/2/02 10:46:13 PM GMT Daylight Time, ChrisAtUpw@....... writes:


For dampin g magnets, I suggest going to Forcefield at http://www.wondermagnet.com/dev/magnets.html and getting a pair of #21's at $4.20 e ach. Type #39 at $12.50 each are even stronger. A sheet of 1/8" copper in the gap feels like it is moving in thick treacle!


Hi Chris,

The best I can find is 1/32 thick copper sheet and as a damping magnet it moves more like it is in very watered down treacle. I f I stacked four of these would I get the same damping effect as if I used a 1/8 thick plate?

Cap
(Casper Hossfield)
Subject: Re: Economical High Quality Magnets From: ChrisAtUpw@....... Date: Sat, 3 Aug 2002 17:13:30 EDT In a message dated 03/08/02, CapAAVSO@....... writes: > Hi Chris, > The best I can find is 1/32 thick copper sheet and as a damping magnet it > moves more like it is in very watered down treacle. If I stacked four of > Hi Cap, I made a typing error. For #21 please read #31. Sorry about that. The price quoted was correct. It would probably not be quite as good, but it could be adequate. Thin sheet Cu is likely to be harder. One important thing to remember is that the Copper needs to extend an appreciable distance beyond the end of the high field change region of the magnets. (Prefereably to between 1.5x or 2x the magnet width) I have a couple of #31s which are separated by 4 mm and the magnets themselves are about 17 mm wide. The magnet pairs are fixed on 5 mm thick iron backing plates (as supplied). The maximum damping is for movements parallel to the long axis of the magnets. The Copper needs to extend at least 10 mm on each side of the central magnet junction, making the plate over 40 mm wide and extending above and below the magnets themselves. My damping plate is a stubby T shape, 50 mm high and about 38 mm wide across the column of the T. The free damping movement is about +/- 2.5 mm. You can feel the difference if you slide the magnet pair up and down the edge of a Cu sheet and compare this drag with that which you get when you put the corner of the sheet through the centre of the gap. Hope that this will help, Regards, Chris Chapman In a message dated 03/08/02, CapAAVSO@....... writes:

Hi Chr is,
The best I can find is 1/32 thick copper sheet and as a damping magnet it moves more like it is in very watered down treacl e. If I stacked four of these would I get the same damping effect as if I used a 1/8 thick plate?


Hi Cap,

      I made a typing error. For #21 please read #31. Sorry about that. The price quoted was correct.

      It would probably not be quite as good, but it could be adequate. Thin sheet Cu is lik ely to be harder. One important thing to remember is that the Copper needs to extend an appreciable distance beyond the end of the high field change region of the magnets. (Prefereably to between 1.5x or 2x the magnet width) I have a couple of #31 s which are separated by 4 mm and the magnets themselves are about 17 mm wide. The magnet pairs are fixed on 5 mm thick iron &n bsp;backing plates (as supplied). The maximum damping is for movements parallel to the long axis of the magnets.  The Copp er needs to extend at least 10 mm on each side of the central magnet junction, making the plate over 40 mm wide and extending a bove and below the magnets themselves. My damping plate is a stubby T shape, 50 mm high and about 38 mm wide across the column of the T. The free damping movement is about +/- 2.5 mm.
      You can feel the difference if you slide the magnet pair up and down the edge of a Cu sheet and compare this drag with that which you get when you put the corner of the sheet through the centre of the gap.  
      Hope that this will help,

      Regards,

      Chris Chapman
Subject: shaking in Panama From: "angel@......... angel@chiriqui.com Date: Tue, 6 Aug 2002 07:13:58 -0500 Hello, Here is a summary of the shaking in Panama. http://www.volcanbaru.com/news.html angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Economical High Quality Magnets From: "Larry Cochrane" cochrane@.............. Date: Tue, 6 Aug 2002 16:38:42 -0700 Greetings, If you are wondering if J. Lehman has anything to do with the Lehman = sensor he, Jim or James Lehman, is the designer of the Lehman sensor = that was described in the 1979 The Amateur Scientist section of the = Scientific American magazine. If you have not read the article I have it = online here: http://www.seismicnet.com/lehmntxt.html -Larry Cochrane Redwood City, PSN ----- Original Message -----=20 From: Connie and Jim Lehman=20 To: psn-l@................. Sent: Friday, August 02, 2002 7:05 AM Subject: Economical High Quality Magnets It was brought to my attention recently a good source of magnets for = coil pickup or damping purposes are to be found in discarded microwave = units. It takes a bit of digging, but within the klystron or similar = box within, in most models there is a pair of strong cylindrical magnets = for the taking. Good digging, J. = Lehman, Harrisonburg, VA.
Greetings,
 
If you are wondering if J. Lehman has = anything to=20 do with the Lehman sensor he, Jim or James Lehman, is the designer of = the Lehman=20 sensor that was described in the 1979 The Amateur Scientist section = of=20 the Scientific American magazine. If you have not read the article = I have=20 it online here: http://www.seismicnet.co= m/lehmntxt.html
 
-Larry Cochrane
Redwood City, PSN
----- Original Message -----
From:=20 Connie and=20 Jim Lehman
Sent: Friday, August 02, 2002 = 7:05=20 AM
Subject: Economical High = Quality=20 Magnets

It was brought to my = attention=20 recently a good source of magnets for coil pickup or damping purposes = are to=20 be found in discarded microwave units.  It takes a bit of = digging, but=20 within the klystron or similar box within, in most models there is a = pair of=20 strong cylindrical magnets for the taking.
          &nbs= p;            = ;            =             &= nbsp;=20 Good digging,  J. Lehman,  Harrisonburg,=20 VA.
Subject: Outage using PSN.QUAKE.NET From: "Larry Cochrane" cochrane@.............. Date: Tue, 6 Aug 2002 19:13:36 -0700 All, Some of you may have experienced problems accessing my web site starting sometime over the weekend. I took a long needed vacation, my first ship cruise to Ensenada Mexico. I had a great time. While I was gone my backup DSL line went down. If you tried to access a URL ending in PSN.QUAKE.NET you would get a timeout error. The problem occurred because the psn.quake.net domain name resolves back to the backup DSL line and I have no control over the domain name to IP address mapping. My first ISP was Quake.Net so they added the PSN part to their domain name server. As far as I know Quake.Net is now out of business, just like a lot of the other small ISP that started up when the Internet got popular. Since this domain name could go way at any time you should change any Bookmarks or Favorites using psn.quake.net to www.seismicnet.com. Also, if you have any web pages that have the old domain name you should change it to the seismicnet.com name. Since I run my own DNS server for seismicnet.com, seismicnet.org and webtronics.com I have compete control over these domain names. Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: M13 quake? From: "David Saum" DSaum@............ Date: Thu, 8 Aug 2002 13:52:11 -0400 Science News has an article this Week of Aug. 3, 2002; Vol. 162, No. 5 that says the imact that wiped out the dinosaurs caused at M13 quake. Registered subscribers can read the article online. References here: http://www.sciencenews.org/20020803/fob2ref.asp West Coast Shimmy: Smack from space triggered landslides along Pacific Coast Scientists say they've found the first evidence along the Pacific Coast of massive landslides triggered by the impact from space 65 million years ago that's suspected to have wiped out the dinosaurs __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: FFT From: "Rolando Benitez" rbenitez@........ Date: Thu, 8 Aug 2002 21:56:59 -0600 Larry et al, I am a newcomer -almost- in this list and an apprentice of the earthquakes sciences, I have been posting events at the PSN web page since late May, having the good fortune to live in the middle of a very active area, I have posted a few. As a beginner I need to learn a lot about many things, I have received wonderful help from several PSN members, thank to them I am enjoying this very much. I would like to address some questions to the group looking for some light in the area of what the FFT module of WINQUAKE is, I've used the filters in a very practical and blind way, so I have a slight idea of what it can be used for, but have no clue in the relationship among the period of sensor and the freq of the event and the proximity of quake, etc, and the FFT screen, so I really need further assistance. Can someone give me some light, please? How can I find some info in the Internet, book, etc.,? Your help would be very appreciated. Best regards from Fraijanes, Guatemala. Rolando Benitez __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: FFT From: "Larry Cochrane" cochrane@.............. Date: Sat, 10 Aug 2002 12:54:55 -0700 Rolando, I'm far from an expert on FFTs. You should be able to fine more information on the Internet if you do a search on Fast Fourier Transform. Many years ago I found some code on the Net that does the FFT. I basically treat the FFT function as a block box. How it works involves a lot of math that's above my head.... What's amazing is it only takes a few lines of "C" code to do the FFT function. To filter the data in WinQuake you should use the Time Domain filtering rather then using the filtering in the FFT Window. The time domain filtering produces less errors or distortion then using the FFT filtering. The reason is errors are introduced when you do the FFT and again when you do the inverse FFT to get the data back into the time domain. The reason for the filtering is to remove unwanted noise in the data. As an example if you record a teleseismic event there is no need for data above one or two Hertz. Since the local man made (or is it person made in these PC times?) noise is usually above one or two Hertz one can do a lowpass filter to remove the local ground noise. Hope this helps. -Larry Cochrane Redwood City, PSN ----- Original Message ----- From: "Rolando Benitez" To: "Psn-L@........... Com" Sent: Thursday, August 08, 2002 8:56 PM Subject: FFT > Larry et al, > I am a newcomer -almost- in this list and an apprentice of the earthquakes > sciences, I have been posting events at the PSN web page since late May, > having the good fortune to live in the middle of a very active area, I have > posted a few. As a beginner I need to learn a lot about many things, I have > received wonderful help from several PSN members, thank to them I am > enjoying this very much. I would like to address some questions to the group > looking for some light in the area of what the FFT module of WINQUAKE is, > I've used the filters in a very practical and blind way, so I have a slight > idea of what it can be used for, but have no clue in the relationship among > the period of sensor and the freq of the event and the proximity of quake, > etc, and the FFT screen, so I really need further assistance. Can someone > give me some light, please? How can I find some info in the Internet, book, > etc.,? Your help would be very appreciated. > Best regards from Fraijanes, Guatemala. > Rolando Benitez > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: FFT From: "Randall Pratt" randallpratts@.......... Date: Thu, 10 Aug 2000 19:56:50 -0500 Hi All, I found this site last spring. It has some good FFT explanation. http://www.dspguide.com/pdfbook.htm Randy ----- Original Message ----- From: "Rolando Benitez" To: "Psn-L@........... Com" Sent: Thursday, August 08, 2002 10:56 PM Subject: FFT > Larry et al, > I am a newcomer -almost- in this list and an apprentice of the earthquakes > sciences, I have been posting events at the PSN web page since late May, > having the good fortune to live in the middle of a very active area, I have > posted a few. As a beginner I need to learn a lot about many things, I have > received wonderful help from several PSN members, thank to them I am > enjoying this very much. I would like to address some questions to the group > looking for some light in the area of what the FFT module of WINQUAKE is, > I've used the filters in a very practical and blind way, so I have a slight > idea of what it can be used for, but have no clue in the relationship among > the period of sensor and the freq of the event and the proximity of quake, > etc, and the FFT screen, so I really need further assistance. Can someone > give me some light, please? How can I find some info in the Internet, book, > etc.,? Your help would be very appreciated. > Best regards from Fraijanes, Guatemala. > Rolando Benitez > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: FFT From: "Barry" gbl@....... Date: Sun, 11 Aug 2002 07:25:03 -0700 Rolando I'll contribute a little. As I understand it, any signal can be representated by a sum of sine waves of different frequencies and magnitudes. With the FFT, the math routine has selected multiples of 2 to speed up the calculation process. You don't get as much of the frequency spectrum but it calculates faster. What you see when you run an FFT is the magnitude sum of the various sign waves ploted as a function of frequency for that given quake and your sensor. I, as an example, usually filter teleseismic events to remove frequencies below 0.003 hz and above 0.5 to 1 hz ( so my files won't be so large.) . You should save events at a sampling frequency twice the value of the highest frequency of interest (Nuquest ). I think what happens if you save higher frequencies than the sampling rate, the sampling picks points on different signal cycles (like a beat) and a higher frequency can look like a low one in the FFT. Regards Barry > > Larry et al, > > I am a newcomer -almost- in this list and an apprentice of the earthquakes > > sciences, I have been posting events at the PSN web page since late May, > > having the good fortune to live in the middle of a very active area, I > have > > posted a few. As a beginner I need to learn a lot about many things, I > have > > received wonderful help from several PSN members, thank to them I am > > enjoying this very much. I would like to address some questions to the > group > > looking for some light in the area of what the FFT module of WINQUAKE is, > > I've used the filters in a very practical and blind way, so I have a > slight > > idea of what it can be used for, but have no clue in the relationship > among > > the period of sensor and the freq of the event and the proximity of quake, > > etc, and the FFT screen, so I really need further assistance. Can someone > > give me some light, please? How can I find some info in the Internet, > book, > > etc.,? Your help would be very appreciated. > > Best regards from Fraijanes, Guatemala. > > Rolando Benitez > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: FFT From: "Randall Pratt" randallpratts@.......... Date: Fri, 11 Aug 2000 14:22:09 -0500 I have a good example of Nyquist frequency behavior in an FFT. I used EMON and substitued the collect routine with a function y=250*sin(m*data point number). In other words, each point was on a pure sine wave and in sync with the sample rate. At the rate of 8.46 samples/sec this resulted in a basic sine wave period of 42.5532 seconds. I then slowed the sample rate by averaging 6 samples per point giving a sample rate of 1.41sps but the wave period remained the same with m=1. Next I incremented m to 20, 40, 60, 80 to effectively increase the frequency by those multiples. I have posted the data file nyquist.fft at http://www.santel.net/~randallpratts/ if you want to play with it. Starting with m=20 or 20* the basic frequency we would expect the period to be 2.1277sec and we measure 2.131 from FFT. Here we would have 3 data points per cycle. The next frequencies are above Nyquist and have fewer than 2 data points in a complete sine wave. The expected frequency goes up and the FFT measured frequency goes down. Notice how both 20 times and 60 times the basic frequency look the same on the FFT. Once the high frequency is aliased in I don't know how it could be filtered out. Someone else may answere that. rn Measured period freq ratio theory ratio expected period meas/exp points/cycle 20 2.145 1.0000 20.00 2.1277 1.01 3.00 40 1.429 1.5010 40.00 1.0638 1.34 1.50 60 2.145 0.6662 60.00 0.7092 3.02 1.00 80 4.293 0.4997 80.00 0.5319 8.07 0.75 Sample rate/2 0.705 sec Nyquist period 1/cutoff 1.42 Randy ----- Original Message ----- From: "Barry" To: Sent: Sunday, August 11, 2002 9:25 AM Subject: Re: FFT > Rolando > I'll contribute a little. As I understand it, any signal can be > representated by a sum of sine waves of different frequencies and > magnitudes. With the FFT, the math routine has selected multiples of 2 to > speed up the calculation process. You don't get as much of the frequency > spectrum but it calculates faster. What you see when you run an FFT is the > magnitude sum of the various sign waves ploted as a function of frequency > for that given quake and your sensor. I, as an example, usually filter > teleseismic events to remove frequencies below 0.003 hz and above 0.5 to 1 > hz ( so my files won't be so large.) . You should save events at a sampling > frequency twice the value of the highest frequency of interest (Nuquest ). > I think what happens if you save higher frequencies than the sampling rate, > the sampling picks points on different signal cycles (like a beat) and a > higher frequency can look like a low one in the FFT. > Regards > Barry > > > > Larry et al, > > > I am a newcomer -almost- in this list and an apprentice of the > earthquakes > > > sciences, I have been posting events at the PSN web page since late May, > > > having the good fortune to live in the middle of a very active area, I > > have > > > posted a few. As a beginner I need to learn a lot about many things, I > > have > > > received wonderful help from several PSN members, thank to them I am > > > enjoying this very much. I would like to address some questions to the > > group > > > looking for some light in the area of what the FFT module of WINQUAKE > is, > > > I've used the filters in a very practical and blind way, so I have a > > slight > > > idea of what it can be used for, but have no clue in the relationship > > among > > > the period of sensor and the freq of the event and the proximity of > quake, > > > etc, and the FFT screen, so I really need further assistance. Can > someone > > > give me some light, please? How can I find some info in the Internet, > > book, > > > etc.,? Your help would be very appreciated. > > > Best regards from Fraijanes, Guatemala. > > > Rolando Benitez > > > > > > __________________________________________________________ > > > > > > Public Seismic Network Mailing List (PSN-L) > > > > > > To leave this list email PSN-L-REQUEST@.............. with > > > the body of the message (first line only): unsubscribe > > > See http://www.seismicnet.com/maillist.html for more information. > > > > > > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > > > > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: WinPlotGPS From: "Larry Cochrane" cochrane@.............. Date: Mon, 12 Aug 2002 23:03:34 -0700 Hi Everyone, A few months ago I started to work on a new program that uses the Location Map Window code in WinQuake to plot the data from a GPS receiver on a map. The program is now ready for beta testing. While not directly related to earthquakes the program can be used to calculate the height and position of your sensor using long term averaging. To use the program you will need either a Motorola ONCORE receiver or any GPS receiver the can output NMEA messages. More information about the program and a download link can be found on this page http://www.seismicnet.com/winplotgps/. Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: DRIP (diamagnetically restored inverted pendulum) From: Bobhelenmcclure@....... Date: Wed, 14 Aug 2002 23:20:24 EDT Hi everyone, A few weeks ago, I hatched a new idea for an old concept, the inverted pendulum, and made a demo model of it for study. It consists of a graphite rod, 3 mm in diameter by 304 mm long, with 13 full turns of 1/8 diameter solder (20 grams) on top to provide the inertial mass. The restoring force for this pendulum is provided by permanent magnets surrounding the graphite, and arranged to form a linear quadrupole field. Graphite is diamagnetic, and is repelled by magnetic field gradients. For a graphite rod immersed in a quadrupole field, this repulsive force is radially symmetric, and linearly proportional to the displacement of the rod from the magnet axis. The restoring torque is proportional to the height of the magnet above the pivot point of the graphite rod. By adjusting the height, one can get a long period pendulum, where the restoring torque is slightly stronger than the destabilizing gravity torque. Damping is provided by a sleeve made of 0.0045 inch thick aluminum foil salvaged from a deli pie plate. Any amount of damping, from none to very over-damped, can be obtained by adjusting the penetration of the sleeve into the magnetic field. My present device is lacking the necessary position sensors, so I can tell you nothing about its performance as a tiltmeter type seismometer. That will have to come later. It should be able to sense horizontal ground motion and direction, if fitted out with a pair of othogonally oriented position sensors. I cut the top off of an empty LP gas bottle to form the support for the magnet. The resulting cylinder is 8.25 inches tall and 2.75 inches O.D. I put a bridge plate inside to form a resting place for the magnet. The magnet and bridge are held in place by a coil spring between the magnet and inner wall. The magnet can be easily axially aligned and centered, and can be adjusted up and down by sliding the spring, magnet, and bridge as a unit up and down within the cylinder. A .375 inch hole was drilled in the bottom of the tank to allow the dully pointed tip of the graphite rod to pivot on the base plate. No tilt adjustment is used. Instead, the bottle is nudged about on the base plate until a point of balance is reached. Fine adjustment is attained by very lightly tapping the base of the bottle with a pencil. Eventually, a top cover will be fabricated which will shield the pendulum from drafts and provide a structure for mounting the pickoffs. A small ball at the bottom end of the rod makes a better, more load bearing, pivot. The graphite rod should be selected for straightness. (You have to buy 12, so you can select the best.) The magnet is made up of 24 each 0.25 inch cube magnets of NdFeB. Six magnets on each side form a 0.25 inch square opening of 1.5 inch length. Four spacers of 0.25 inch copper tubing hold the magnets in position as well as four 0.125 thick steel plates lap-jointed around the outside of the assembly. The assembly is self-assembling (if you do it right) and self supporting, excepting for a tendency for the magnets to separate themselves axially. Four brass bolts through the copper spacers keep the magnets axially confined. The natural period of this device is temperature sensitive, because the magnetic field is temperature sensitive. Furthermore, the restoring force is a function of the square of the magnetic field, making the sensitivity even greater. The very delicate balance of restoring force against gravity force causes the period to very temperature dependent. Right now, the pendulum is set up on my basement floor on a base plate of Corian, set up for a period of 5 seconds. I will monitor the balance of the pendulum to see how well it remains centered over the next few days. The magnets were purchased from amazingmagnets.com and the graphite spectrographic grade rods from tedpella.com. I wish to acknowledge the help and advice of Chris Chapman and the encouragement provided by John Lahr, Meredith Lamb, and David Lamb in this endeavor. Regards, Bob McClure Hi everyone,

  A few weeks ago, I hatched a new idea for an old concept, the inverted pendulum, and made a demo model of it for study.& nbsp; It consists of a graphite rod, 3 mm in diameter by 304 mm long, with 13 full turns of 1/8 diameter solder (20 grams) on t op to provide the inertial mass.  The restoring force for this pendulum is provided by permanent magnets surrounding the g raphite, and arranged to form a linear quadrupole field.  Graphite is diamagnetic, and is repelled by magnetic field gradi ents.  For a graphite rod immersed in a quadrupole field, this repulsive force is radially symmetric, and linearly proport ional to the displacement of the rod from the magnet axis.  The restoring torque is proportional to the height of the magn et above the pivot point of the graphite rod.  By adjusting the height, one can get a long period pendulum, where the rest oring torque is slightly stronger than the destabilizing gravity torque.

  Damping is provided by a sleeve made of 0.0045 inch thick aluminum foil salvaged from a deli pie plate.  Any amount of damping, from none to very over-damped, can be obtained by adjusting the penetration of the sleeve into the magnetic field.

  My present device is lacking the necessary position sensors, so I can tell you nothing about its performance as a tiltme ter type seismometer.  That will have to come later.  It should be able to sense horizontal ground motion and directi on, if fitted out with a pair of othogonally oriented position sensors.

  I cut the top off of an empty LP gas bottle to form the support for the magnet.  The resulting cylinder is 8.25 inc hes tall and 2.75 inches O.D.  I put a bridge plate inside to form a resting place for the magnet.  The magnet and br idge are held in place by a coil spring between the magnet and inner wall.  The magnet can be easily axially aligned and c entered, and can be adjusted up and down by sliding the spring, magnet, and bridge as a unit up and down within the cylinder.&n bsp; A .375 inch hole was drilled in the bottom of the tank to allow the dully pointed tip of the graphite rod to pivot on the base plate.  No tilt adjustment is used.  Instead, the bottle is nudged about on the base plate until a point of bala nce is reached.  Fine adjustment is attained by very lightly tapping the base of the bottle with a pencil.  Eventuall y, a top cover will be fabricated which will shield the pendulum from drafts and provide a structure for mounting the pickoffs. A small ball at the bottom end of the rod makes a better, more load bearing, pivot.  The graphite rod should be selected for straightness.  (You have to buy 12, so you can select the best.)

  The magnet is made up of 24 each 0.25 inch cube magnets of NdFeB.  Six magnets on each side form a 0.25 inch square opening of 1.5 inch length.  Four spacers of 0.25 inch copper tubing hold the magnets in position as well as four 0.125 t hick steel plates lap-jointed around the outside of the assembly.  The assembly is self-assembling (if you do it right) an d self supporting, excepting for a tendency for the magnets to separate themselves axially.  Four brass bolts through the copper spacers keep the magnets axially confined.

  The natural period of this device is temperature sensitive, because the magnetic field is temperature sensitive.  F urthermore, the restoring force is a function of the square of the magnetic field, making the sensitivity even greater.  T he very delicate balance of restoring force against gravity force causes the period to very temperature dependent.  Right now, the pendulum is set up on my basement floor on a base plate of Corian, set up for a period of 5 seconds.  I will moni tor the balance of the pendulum to see how well it remains centered over the next few days.

  The magnets were purchased from amazingmagnets.com and the graphite spectrographic grade rods from tedpella.com.

  I wish to acknowledge the help and advice of Chris Chapman and the encouragement provided by John Lahr, Meredith Lamb, a nd David Lamb in this endeavor.

Regards,  Bob McClure
Subject: Re: DRIP (diamagnetically restored inverted pendulum) From: "George Harris" gjharris@............. Date: Wed, 14 Aug 2002 22:28:16 -0700 ----- Original Message -----=20 From: Bobhelenmcclure@.......... To: psn-l@................. Sent: Wednesday, August 14, 2002 8:20 PM Subject: DRIP (diamagnetically restored inverted pendulum) My present device is lacking the necessary position sensors, so I can = tell you nothing about its performance as a tiltmeter type seismometer. = That will have to come later. It should be able to sense horizontal = ground motion and direction, if fitted out with a pair of othogonally = oriented position sensors. A suggestion from George Harris A very sensitive and inexpensive two axis sensor can be made as = follows: Above the top surface of the pendulum, place an LED with the front = surface=20 flattened so that it become a point source about 1/4 inch above the = surface. On the top surface cement a 6mm square mirror (stock H43866 from = Edmund). On each of the four sides of the LED place small solar cells (stock = 980-0150 from allied) in such a position that each will be half illuminated by = the LED. The photocells can be connected in parallel, plus to minus, on the = opposite sides across the inputs to a low noise operational amplifier = (like an OP27 from Precision monolithics) with about a megohm in the = feedback. The resulting output is very sensitive (nanometers) and = linear. To check the sensitivity, I mounted the assembly on a three point = platform with a dial indicator on one end of the platform. Tilting the platform by = small motions of a support screw permits the accurate measurement of the = anglular (or acceleration) sensitivity.
 
----- Original Message -----
From:=20 Bobhelenmcclure@.......
Sent: Wednesday, August 14, = 2002 8:20=20 PM
Subject: DRIP (diamagnetically = restored=20 inverted pendulum)

My present device is lacking the necessary = position=20 sensors, so I can tell you nothing about its performance as a = tiltmeter type=20 seismometer.  That will have to come later.  It should be = able to=20 sense horizontal ground motion and direction, if fitted out with a = pair of=20 othogonally oriented position sensors.
A suggestion from George = Harris
 
A very sensitive and inexpensive two axis sensor = can be=20 made as follows:
 
Above the top surface of the pendulum, place an = LED with=20 the front surface
flattened so that it become a point source about = 1/4 inch=20 above the surface.
On the top surface cement a 6mm square mirror = (stock H43866=20 from Edmund).
On each of the four sides of the LED place small = solar=20 cells (stock 980-0150
from allied) in such a position that each will be = half=20 illuminated by the LED.
 
The photocells can be connected in parallel, plus = to minus,=20 on the opposite sides across the inputs=20 to a low noise operational amplifier (like an OP27 from Precision = monolithics)=20 with about a megohm in the feedback.  The resulting output is = very=20 sensitive (nanometers) and linear.
 
To check the sensitivity, I mounted = the assembly=20 on a three point platform with
a dial indicator on one end of the=20 platform.  Tilting the platform by small motions of a support = screw=20 permits the accurate measurement of the anglular (or acceleration)=20 sensitivity.
 
Subject: Re: DRIP (diamagnetically restored inverted pendulum) From: ChrisAtUpw@....... Date: Fri, 16 Aug 2002 07:48:42 EDT In a message dated 15/08/02, gjharris@............. writes: > A very sensitive and inexpensive two axis sensor can be made as follows: > > Above the top surface of the pendulum, place an LED with the front surface > > On the top surface cement a 6mm square mirror (stock H43866 from Edmund). > On each of the four sides of the LED place small solar cells (stock 980-0150 > from allied) in such a position that each will be half illuminated by the > Hello George Harris, Nice to have some extra input! I am having a problem in visualising the optical layout you suggest and the orientation and position of the various components. Is the LED 'water clear' plastic or what, please? What size? Are they IR or visible? When you cut the end off a plastic LED and polish the end, looking into it, you see a bright central square chip surrounded by a ring of light from the plastic case. Putting a mirror on the end just reflects most of the light back through the base. Is that any chance of a quick sketch / 'paint' drawing, please? Edmund optics seem to be at http://www.edmundoptics.com/ There is no response to H43866, but there is a 10 mm square surface mirror NT45-517 @....... > The photocells can be connected in parallel, plus to minus, on the opposite > sides across the inputs to a low noise operational amplifier with about a > megohm in the feedback. The resulting output is very sensitive > The photo output of LEDs varies exponentially with temperature and you get about a factor of five reduction in light output at a constant current if you increase the temperature from 0 C to 100 C. Since you can expect ambient changes of >10 C deg and the LEDs themselves can heat up considerably, the variations are significant. How do you stabilise the photo output please? Regards, Chris Chapman In a message dated 15/08/02, gjharris@............. writes:

A very sensitive and inexpensive two axis sensor can be made as follows:

Above the top surface of the pendulum, place an LED with the front surface
flattened so that it become a point source about 1/4 inch above the surface.


On the top surface cement a 6mm square mirror (stock H43866 from Edmund).
On each of the four sides of the LED place small solar cells (stock 980-0150
from allied) in such a position that each will be half illuminated by the LED.


Hello George Harris,

     Nice to have some extra input! I am having a problem in visualising the optical layout you s uggest and the orientation and position of the various components. Is the LED 'water clear' plastic or what, please? What size? Are they IR or visible?  
      When you cut the end off a plastic LED and polish the end, looking into it, you see a bright central square chip surrounded by a ring of light from the plastic case. Putting a mirror on the end just reflects most of the light back through the base.
      Is that any chance of a quick sketch / 'paint' drawing, please?

      Edmund optics seem to be at http://www.edmundoptics.com/  There is no response to H43866, but there is a 10 mm square surface mirror NT45-517 @.......
 
The ph otocells can be connected in parallel, plus to minus, on the opposite sides across the inputs to a low noise operational amplif ier with about a megohm in the feedback.  The resulting output is very sensitive (nanometers) and linear.


     The photo output of LEDs varies exponentially with temperature and you get about a factor of five reduction in light output at a constant current if you increase the temperature from 0 C to 100 C. Since you can expect a mbient changes of >10 C deg and the LEDs themselves can heat up considerably, the variations are significant. How do you sta bilise the photo output please?

   Regards,

     Chris Chapman
Subject: ebay auction From: BOB BARNS royb1@........... Date: Fri, 16 Aug 2002 08:12:30 -0400 Hi gang, A friend has one of these-a nice piece of hardware: KINETIC SYSTEMS MODEL SH-1 SEISMOMETER Item # 2130828594 Ends Aug-19-02 19:47:15 PDT goto ebay.com Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: DRIP (diamagnetically restored inverted pendulum) From: "George Harris" gjharris@............. Date: Sat, 17 Aug 2002 17:11:23 -0700 ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Friday, August 16, 2002 4:48 AM Subject: Re: DRIP (diamagnetically restored inverted pendulum) In a message dated 15/08/02, gjharris@............. writes:=20 A very sensitive and inexpensive two axis sensor can be made as = follows:=20 Above the top surface of the pendulum, place an LED with the front = surface=20 flattened so that it become a point source about 1/4 inch above the = surface. On the top surface cement a 6mm square mirror (stock H43866 from = Edmund).=20 On each of the four sides of the LED place small solar cells (stock = 980-0150=20 from allied) in such a position that each will be half illuminated = by the LED. Hello George Harris,=20 Nice to have some extra input! I am having a problem in = visualising the optical layout you suggest and the orientation and = position of the various components. Is the LED 'water clear' plastic or = what, please? What size? Are they IR or visible? =20 When you cut the end off a plastic LED and polish the end, = looking into it, you see a bright central square chip surrounded by a = ring of light from the plastic case. Putting a mirror on the end just = reflects most of the light back through the base.=20 Is that any chance of a quick sketch / 'paint' drawing, please?=20 Edmund optics seem to be at http://www.edmundoptics.com/ There = is no response to H43866, but there is a 10 mm square surface mirror = NT45-517 @.......... =20 Response By George***************8 The LED I used was the small clear type. I sandpapered the surface = until it was very close to the LED, then used finer sandpaper and polishing = compound (tooth paste works) until it was bright. This LED was mounted on a small PC board above the top surface of the pendulum looking down. The spacing = should be approximately 1/4 inch above the mirror which was attached to = the upper surface. The mirror used was 6 mm square (1/4 inch). The resulting = reflection is=20 approximately a 1/2 inch square at the surface of the PC board. If now = small silicon photosensors are placed on the same board approximately = 1/2 inch apart, they will each be illuminated on 1/2 of their surface = when the mirror is centered. =20 The sensors I used are about 3mm (1/8 inch) square and moung flat to = the board. The photocells can be connected in parallel, plus to minus, on the = opposite sides across the inputs to a low noise operational amplifier = with about a megohm in the feedback. The resulting output is very = sensitive (nanometers) and linear. The photo output of LEDs varies exponentially with temperature = and you get about a factor of five reduction in light output at a = constant current if you increase the temperature from 0 C to 100 C. = Since you can expect ambient changes of >10 C deg and the LEDs = themselves can heat up considerably, the variations are significant. How = do you stabilise the photo output please?=20 Response********** Since the photocells are both half illuminated, the null is not = sensitive to the output of the LED. The changes in the LED ouput would only slightly = effect the gain of the system. Since I was using the sensor in a = feedback mode to recenter the mass, this effect was minimal. My system was in a heated area, so = the=20 LED output change was very small. Regards,=20 Chris Chapman=20
 
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Friday, August 16, 2002 = 4:48=20 AM
Subject: Re: DRIP = (diamagnetically=20 restored inverted pendulum)

In a = message dated=20 15/08/02, gjharris@.............=20 writes:

A very sensitive and inexpensive two axis sensor can be = made as=20 follows:

Above the top surface of the pendulum, place an LED = with=20 the front surface
flattened so that it become a point source = about 1/4=20 inch above the surface. On the top surface cement a 6mm square mirror (stock = H43866 from=20 Edmund).
On each of the four sides of the LED place small solar = cells=20 (stock 980-0150
from allied) in such a position that each will = be half=20 illuminated by the LED.


Hello George Harris, =

     Nice=20 to have some extra input! I am having a problem in visualising the = optical=20 layout you suggest and the orientation and position of the various = components.=20 Is the LED 'water clear' plastic or what, please? What size? Are they = IR or=20 visible?  
      When you cut = the end=20 off a plastic LED and polish the end, looking into it, you see a = bright=20 central square chip surrounded by a ring of light from the plastic = case.=20 Putting a mirror on the end just reflects most of the light back = through the=20 base.
      Is that any chance of a = quick=20 sketch / 'paint' drawing, please?=20

      Edmund optics seem to be = at=20 http://www.edmundoptics.com/  There is no response to H43866, but = there=20 is a 10 mm square surface mirror NT45-517 @.......
 
Response By George***************8
 
The LED I used was the small clear type.  I sandpapered the = surface=20 until it was
very close to the LED, then used finer sandpaper and polishing = compound=20 (tooth
paste works) until it was bright.  This LED was mounted on a = small=20 PC
board above the top surface of the pendulum looking down.  = The=20 spacing should be approximately 1/4 inch above the mirror which = was=20 attached to the upper
surface.  The mirror used was 6 mm square (1/4 inch).  = The=20 resulting reflection is
approximately a 1/2 inch square at the surface of the PC = board. If=20 now small silicon photosensors are placed on the same board = approximately 1/2=20 inch apart, they will each be illuminated on 1/2 of their surface when = the=20 mirror is centered. 
The sensors I used are about 3mm (1/8 = inch)=20 square and moung flat to the board.
The photocells can be connected in parallel, plus to = minus, on=20 the opposite sides across the inputs to a low noise operational = amplifier=20 with about a megohm in the feedback.  The resulting output is = very=20 sensitive (nanometers) and linear.


     The photo output of LEDs = varies=20 exponentially with temperature and you get about a factor of five = reduction in=20 light output at a constant current if you increase the temperature = from 0 C to=20 100 C. Since you can expect ambient changes of >10 C deg and the = LEDs=20 themselves can heat up considerably, the variations are significant. = How do=20 you stabilise the photo output please?
Response**********
 
Since the photocells are both half illuminated, the null is = not=20 sensitive to the
output of the LED.  The changes in the LED ouput would only = slightly=20 effect the gain of the system.  Since I was using the sensor in a = feedback mode to recenter
the mass, this effect was minimal.  My system was in a = heated area,=20 so the
LED output change was very small.

   Regards,=20

     Chris Chapman
=20
Subject: Re: DRIP (diamagnetically restored inverted pendulum) From: "S Shufflebotham" Cellectronic@.............. Date: Sun, 18 Aug 2002 10:15:05 +0100 Hi All, I have been reading your mails regarding "DRIP".=20 With reference to the cut and polished L.E.D. I was wondering if you are = aware that flat L.E.D.s are available, I have found several of these in = cellular telephone keypads for illumination purposes, my thought is if = these are OK for your purpose it might save you some work. Just a = thought ! Kind Regards=20 Steve ----- Original Message -----=20 From: George Harris=20 To: psn-l@................. Sent: Sunday, August 18, 2002 1:11 AM Subject: Re: DRIP (diamagnetically restored inverted pendulum) ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Friday, August 16, 2002 4:48 AM Subject: Re: DRIP (diamagnetically restored inverted pendulum) In a message dated 15/08/02, gjharris@............. writes:=20 A very sensitive and inexpensive two axis sensor can be made as = follows:=20 Above the top surface of the pendulum, place an LED with the front = surface=20 flattened so that it become a point source about 1/4 inch above = the surface. On the top surface cement a 6mm square mirror (stock H43866 from = Edmund).=20 On each of the four sides of the LED place small solar cells = (stock 980-0150=20 from allied) in such a position that each will be half illuminated = by the LED. Hello George Harris,=20 Nice to have some extra input! I am having a problem in = visualising the optical layout you suggest and the orientation and = position of the various components. Is the LED 'water clear' plastic or = what, please? What size? Are they IR or visible? =20 When you cut the end off a plastic LED and polish the end, = looking into it, you see a bright central square chip surrounded by a = ring of light from the plastic case. Putting a mirror on the end just = reflects most of the light back through the base.=20 Is that any chance of a quick sketch / 'paint' drawing, = please?=20 Edmund optics seem to be at http://www.edmundoptics.com/ = There is no response to H43866, but there is a 10 mm square surface = mirror NT45-517 @.......... =20 Response By George***************8 The LED I used was the small clear type. I sandpapered the surface = until it was very close to the LED, then used finer sandpaper and polishing = compound (tooth paste works) until it was bright. This LED was mounted on a small = PC board above the top surface of the pendulum looking down. The = spacing should be approximately 1/4 inch above the mirror which was = attached to the upper surface. The mirror used was 6 mm square (1/4 inch). The resulting = reflection is=20 approximately a 1/2 inch square at the surface of the PC board. If = now small silicon photosensors are placed on the same board = approximately 1/2 inch apart, they will each be illuminated on 1/2 of = their surface when the mirror is centered. =20 The sensors I used are about 3mm (1/8 inch) square and moung flat to = the board. The photocells can be connected in parallel, plus to minus, on the = opposite sides across the inputs to a low noise operational amplifier = with about a megohm in the feedback. The resulting output is very = sensitive (nanometers) and linear. The photo output of LEDs varies exponentially with temperature = and you get about a factor of five reduction in light output at a = constant current if you increase the temperature from 0 C to 100 C. = Since you can expect ambient changes of >10 C deg and the LEDs = themselves can heat up considerably, the variations are significant. How = do you stabilise the photo output please?=20 Response********** Since the photocells are both half illuminated, the null is not = sensitive to the output of the LED. The changes in the LED ouput would only slightly = effect the gain of the system. Since I was using the sensor in a = feedback mode to recenter the mass, this effect was minimal. My system was in a heated area, = so the=20 LED output change was very small. Regards,=20 Chris Chapman=20
Hi All, I have been reading your mails = regarding=20 "DRIP".
With reference to the cut and polished = L.E.D. I was=20 wondering if you are aware that flat L.E.D.s are available, I have found = several=20 of these in cellular telephone keypads for illumination purposes, my = thought is=20 if these are OK for your purpose it might save you some work. Just a = thought=20 !
 
Kind Regards
Steve
----- Original Message -----
From:=20 George=20 Harris
Sent: Sunday, August 18, 2002 = 1:11=20 AM
Subject: Re: DRIP = (diamagnetically=20 restored inverted pendulum)

 
----- Original Message -----
From:=20 ChrisAtUpw@.......
To: psn-l@..............
Sent: Friday, August 16, 2002 = 4:48=20 AM
Subject: Re: DRIP = (diamagnetically=20 restored inverted pendulum)

In a = message dated=20 15/08/02, gjharris@.............=20 writes:

A very sensitive and inexpensive two axis sensor can = be made=20 as follows:

Above the top surface of the pendulum, place = an LED=20 with the front surface
flattened so that it become a point = source=20 about 1/4 inch above the surface. On the top surface cement a 6mm square mirror (stock = H43866=20 from Edmund).
On each of the four sides of the LED place small = solar=20 cells (stock 980-0150
from allied) in such a position that = each will=20 be half illuminated by the LED.


Hello George Harris, =

     Nice=20 to have some extra input! I am having a problem in visualising the = optical=20 layout you suggest and the orientation and position of the various=20 components. Is the LED 'water clear' plastic or what, please? What = size? Are=20 they IR or visible?   =
      When you=20 cut the end off a plastic LED and polish the end, looking into it, = you see a=20 bright central square chip surrounded by a ring of light from the = plastic=20 case. Putting a mirror on the end just reflects most of the light = back=20 through the base.
      Is that = any chance=20 of a quick sketch / 'paint' drawing, please?=20

      Edmund optics seem to be = at=20 http://www.edmundoptics.com/  There is no response to H43866, = but there=20 is a 10 mm square surface mirror NT45-517 @.......
 
Response By George***************8
 
The LED I used was the small clear type.  I sandpapered = the=20 surface until it was
very close to the LED, then used finer sandpaper and polishing = compound=20 (tooth
paste works) until it was bright.  This LED was mounted on = a small=20 PC
board above the top surface of the pendulum looking down.  = The=20 spacing should be approximately 1/4 inch above the mirror which = was=20 attached to the upper
surface.  The mirror used was 6 mm square (1/4 = inch).  The=20 resulting reflection is
approximately a 1/2 inch square at the surface of the PC = board. If=20 now small silicon photosensors are placed on the same board = approximately=20 1/2 inch apart, they will each be illuminated on 1/2 of their = surface when=20 the mirror is centered. 
The sensors I used are about 3mm = (1/8=20 inch) square and moung flat to the board.
The photocells can be connected in parallel, plus to = minus, on=20 the opposite sides across the inputs to a low noise operational = amplifier=20 with about a megohm in the feedback.  The resulting output is = very=20 sensitive (nanometers) and linear.


     The photo output of LEDs = varies=20 exponentially with temperature and you get about a factor of five = reduction=20 in light output at a constant current if you increase the = temperature from 0=20 C to 100 C. Since you can expect ambient changes of >10 C deg and = the=20 LEDs themselves can heat up considerably, the variations are = significant.=20 How do you stabilise the photo output please?
Response**********
 
Since the photocells are both half illuminated, the null = is not=20 sensitive to the
output of the LED.  The changes in the LED ouput would = only=20 slightly effect the gain of the system.  Since I was using the = sensor=20 in a feedback mode to recenter
the mass, this effect was minimal.  My system was in a = heated=20 area, so the
LED output change was very small.

   Regards,=20

     Chris Chapman
=20
Subject: Re: DRIP (diamagnetically restored inverted pendulum) From: ChrisAtUpw@....... Date: Sun, 18 Aug 2002 10:31:51 EDT In a message dated 18/08/02, Cellectronic@.............. writes: > Hi All, I have been reading your mails regarding "DRIP". > With reference to the cut and polished L.E.D. I was wondering if you are > aware that flat L.E.D.s are available, I have found several of these in > cellular telephone keypads for illumination purposes, my thought is if > Hi Steve, Thanks for the input! There is a discussion regarding LEDs and filament lamps. You won't get a light source quieter than a well regulated filament and you can get high outputs. LEDs tend to be noisier, sometimes a lot noisier. The 'quantum well' superbright orange and red ones are fairly quiet and so are the IR LEDs. Whereas a filament will not pass on high frequency noise from the power supply, LEDs will. The main problem with LEDs for seismometer applications is drift due to temperature changes / heating. (Lasers are incredibly noisy and should be avoided.) The photo output of LEDs varies exponentially with temperature and you may get about a factor of five reduction in light output at a constant current if you increase the temperature from 0 C to 100 C. Since you can expect ambient changes of >10 C deg and the LEDs themselves can heat up considerably, the variations are very significant. While you can balance out the zero fairly well using a common source, having the scale uncertain within 50% is clearly not helpful. With a pair of Si or GaAs photo sensors operating in current mode, you can add the outputs to determine the illumination level that you want to regulate and subtract the outputs to give the sensor dispacement. Superbright orange is well matched to GaAs and IR is matched to silicon. It is a great advantage to use LEDs which have a metal can backing, since this enables you to dissipate the heat / control the temperature. You can get metal can LEDs with flat windows, metal backed LEDs with epoxy encapsulation and LID ceramic chip leds. There is a relationship between the resolution that you can get, the overall range, the response time and the photocurrent. With maybe +/- 1 mm range and 10 Hz, it is not too difficult to get a noise floor ~20 nm. This is OK for amateur seismometers which do not drift significantly or which have force feedback. Reducing the range or the bandwidth enables you to improve the resolution. Regards, Chris Chapman In a message dated 18/08/02, Cellectronic@.............. writes:

Hi All , I have been reading your mails regarding "DRIP".
With reference to the cut and polished L.E.D. I was wondering if you are aware that flat L.E.D.s are available, I have foun d several of these in cellular telephone keypads for illumination purposes, my thought is if these are OK for your purpose it m ight save you some work.


Hi Steve,

      Thanks for the input! There is a discussion regarding LEDs and filament lamps. You won 't get a light source quieter than a well regulated filament and you can get high outputs. LEDs tend to be noisier, sometimes a lot noisier. The 'quantum well' superbright orange and red ones are fairly quiet and so are the IR LEDs. Whereas a filament wi ll not pass on high frequency noise from the power supply, LEDs will. The main problem with LEDs for seismometer applications i s drift due to temperature changes / heating. (Lasers are incredibly noisy and should be avoided.)
    The photo output of LEDs varies exponentially with temperature and you may get about a factor of f ive reduction in light output at a constant current if you increase the temperature from 0 C to 100 C. Since you can expect amb ient changes of >10 C deg and the LEDs themselves can heat up considerably, the variations are very significant. While you c an balance out the zero fairly well using a common source, having the scale uncertain within 50% is clearly not helpful. With a pair of Si or GaAs photo sensors operating in current mode, you can add the outputs to determine the illumination level that y ou want to regulate and subtract the outputs to give the sensor dispacement. Superbright orange is well matched to GaAs and IR is matched to silicon.
   It is a great advantage to use LEDs which have a metal can backing, since this enables you to dissipate the heat / control the temperature. You can get metal can LEDs with flat windows, metal backed LEDs with epoxy encapsulation an d LID ceramic chip leds.
      There is a relationship between the resolution that you can get, the overall range, th e response time and the photocurrent. With maybe +/- 1 mm range and 10 Hz, it is not too difficult to get a noise floor ~20 nm. This is OK for amateur seismometers which do not drift significantly or which have force feedback. Reducing the range or the b andwidth enables you to improve the resolution.

      Regards,

      Chris Chapman  
Subject: WinSDR Timing From: "Bob Hancock" robert.hancock@........... Date: Sun, 18 Aug 2002 20:13:20 -0400 Has anyone had any experience in the use of Internet timing for WinSDR. I am interested in what is considered the maximum timing error that is acceptable for amateur seismic work, and also the recommended minimum recheck time. In other words how often should the timing server be checked. I live in an apartment complex, on the bottom floor. There are numerous trees nearby which would block a GPS receiver, and management does not want an external antenna. I am also experiencing difficulty in getting a good WWV signal. If anyone has had either good or bad experiences with any particular program I would also be interested in hearing. Thank You Bob Hancock Randolph, NJ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: WinSDR Timing From: "angel@......... angel@chiriqui.com Date: Sun, 18 Aug 2002 20:08:06 -0500 Hello Bob, Sunday, August 18, 2002, 7:13:20 PM, you wrote: BH> Has anyone had any experience in the use of Internet timing for WinSDR. I BH> am interested in what is considered the maximum timing error that is BH> acceptable for amateur seismic work, and also the recommended minimum BH> recheck time. In other words how often should the timing server be checked. I use Tardis on several seismographs and the time is just great. I run it as a service and it has a feature that does the recheck automatically timed based on the drift of you PC clock. I have permanent connection to the internet. You can combine Tardis with something like Rightime which can learn to regulate you own computers timers to within a few tenths of millisecond per week. I would use this on any computer that did not have a permanent connection. BH> I live in an apartment complex, on the bottom floor. There are numerous BH> trees nearby which would block a GPS receiver, and management does not want BH> an external antenna. I am also experiencing difficulty in getting a good BH> WWV signal. BH> If anyone has had either good or bad experiences with any particular program BH> I would also be interested in hearing. I have had very good experience with Tardis angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: WinSDR Timing From: Hammonds hammond@........... Date: Sun, 18 Aug 2002 17:23:29 -0800 Bob, check out http://www.atomtime.com/ for a source of seismic timing via the internet. I've used it and with good results. Rightime http://www.rightime.com/ is a similar program which works well. It will take care of that nasty PC clock drift. I suggest that to compare local and regional seismic data with other stations, your clock needs to be accurate to within 100 ms of UTC at most. Bob Hammond Fairbanks, AK http://apsn.awcable.com At 04:13 PM 8/18/2002, you wrote: >Has anyone had any experience in the use of Internet timing for WinSDR. I >am interested in what is considered the maximum timing error that is >acceptable for amateur seismic work, and also the recommended minimum >recheck time. In other words how often should the timing server be checked. > >I live in an apartment complex, on the bottom floor. There are numerous >trees nearby which would block a GPS receiver, and management does not want >an external antenna. I am also experiencing difficulty in getting a good >WWV signal. > >If anyone has had either good or bad experiences with any particular program >I would also be interested in hearing. > >Thank You > >Bob Hancock >Randolph, NJ > > > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: WinSDR Timing From: "Larry Cochrane" cochrane@.............. Date: Sun, 18 Aug 2002 18:56:03 -0700 Bob and others, I like to use the free NTP port for Windows. You can download it from my site here http://www.seismicnet.com/software/ntp4171.zip or here http://www.five-ten-sg.com/. The NTP runs as a service and will keep the systems time accurate to a few milliseconds. It can also act as a time server so it can be used to keep accurate time on other systems on your LAN. I use it to keep my Win2K development system's time accurate. Using WinSDR in the Local Time reference mode you can keep the A/D boards time accurate to within few milliseconds. You do need a dedicated high speed Internet connection to get these type of time accuracies. It is important that the time program you use with WinSDR not jerk the system time around. NTP (and maybe other time setting programs) continuously monitors and adjust the system time in small steps. If the time program makes large adjustments, say larger then ~10 milliseconds, the A/D board will have a hard time trying to figure out what drift is of it's own crystal oscillator located on the A/D board. This is what my ntp.conf file looks like. This file should be located in the \WINNT\System32\drivers\etc\ directory. # NTP configuration file server montpelier.ilan.caltech.edu # you need to change this to a time server near you server ntp1.mainecoon.com # you need to change this to a time server near you # directory and name for drift file - you may need to change this line driftfile C:\WINNT\System32\drivers\etc\ntp.drift # directory for stats - you may need to change this line statsdir C:\WINNT\System32\drivers\etc\ filegen loopstats file loopstats type month enable -Larry Cochrane Redwood City, PSN ----- Original Message ----- From: "Bob Hancock" To: "psn-l@........... com" Sent: Sunday, August 18, 2002 5:13 PM Subject: WinSDR Timing > Has anyone had any experience in the use of Internet timing for WinSDR. I > am interested in what is considered the maximum timing error that is > acceptable for amateur seismic work, and also the recommended minimum > recheck time. In other words how often should the timing server be checked. > > I live in an apartment complex, on the bottom floor. There are numerous > trees nearby which would block a GPS receiver, and management does not want > an external antenna. I am also experiencing difficulty in getting a good > WWV signal. > > If anyone has had either good or bad experiences with any particular program > I would also be interested in hearing. > > Thank You > > Bob Hancock > Randolph, NJ > > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: WinSDR Timing From: steve hammond shammon1@............. Date: Sun, 18 Aug 2002 19:49:56 -0700 Bob, I have had real good luck running Rightime. My clock drift per week on two different systems is now about .04 seconds after the learning period. Regards, Steve Hammond -----Original Message----- From: Hammonds [SMTP:hammond@............ Sent: Sunday, August 18, 2002 6:23 PM To: psn-l@.............. Subject: Re: WinSDR Timing Bob, check out http://www.atomtime.com/ for a source of seismic timing via the internet. I've used it and with good results. Rightime http://www.rightime.com/ is a similar program which works well. It will take care of that nasty PC clock drift. I suggest that to compare local and regional seismic data with other stations, your clock needs to be accurate to within 100 ms of UTC at most. Bob Hammond Fairbanks, AK http://apsn.awcable.com At 04:13 PM 8/18/2002, you wrote: >Has anyone had any experience in the use of Internet timing for WinSDR. I >am interested in what is considered the maximum timing error that is >acceptable for amateur seismic work, and also the recommended minimum >recheck time. In other words how often should the timing server be checked. > >I live in an apartment complex, on the bottom floor. There are numerous >trees nearby which would block a GPS receiver, and management does not want >an external antenna. I am also experiencing difficulty in getting a good >WWV signal. > >If anyone has had either good or bad experiences with any particular program >I would also be interested in hearing. > >Thank You > >Bob Hancock >Randolph, NJ > > > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: WinSDR Timing From: ChrisAtUpw@....... Date: Mon, 19 Aug 2002 00:12:38 EDT In a message dated 19/08/02, robert.hancock@........... writes: > I am also experiencing difficulty in getting a good WWV signal. Hi Robert, WWV is broadcast on 2.5, 5, 10, 15, 20 and 25 MHz. You didn't say which A/D you were using, but it should be set to keep good enough time so that it only needs adjusting twice a day, if that. The night time radio signals are likely to be stronger than the daytime ones. If you can't use an external wire aerial, can't you use a tuned frame aerial? Regards, Chris Chapman In a message dated 19/08/02, robert.hancock@........... writes:

I am also experiencing difficulty in getting a good WWV signal.


Hi Robert,

      WWV is broadcast on 2.5, 5, 10, 15, 20 and 25 MHz. You didn't say which A/D you were u sing, but it should be set to keep good enough time so that it only needs adjusting twice a day, if that. The night time radio signals are likely to be stronger than the daytime ones. If you can't use an external wire aerial, can't you use a tuned frame aerial?  

      Regards,

      Chris Chapman



Subject: A Request... From: "PAMA" chimanee@............. Date: Tue, 20 Aug 2002 06:36:43 +0530 Dear Colleauges, I am working on a low cost laser based seismometer for sensing = microseisms. I am located at Shillong in India and this is a part of = project for developing instrumentation and arrays for an Internet based = early warning system. This is a earthquake prone area and close to a = major fault zone. Would welcome any information or assistance which = would be gratefully acknowledged.=20 Thanking you in anticipation, Regards, Dr. (Ms) P.V.Koparkar Professor & Head University Science and Instrumentation Centre North Eastern Hill University Shillong 793 022 India
Dear Colleauges,
 
I am working on a low cost = laser based=20 seismometer for sensing microseisms. I am located at Shillong = in India and=20 this is a part of project for developing instrumentation and arrays for = an=20 Internet based early warning system. This is a earthquake prone area and = close=20 to a major fault zone. Would welcome any information or assistance which = would=20 be gratefully acknowledged.
 
Thanking you in=20 anticipation,
Regards,
 
Dr. (Ms)=20 P.V.Koparkar
Professor & Head
University Science and=20 Instrumentation Centre
North Eastern Hill University
Shillong 793 = 022=20 India

Subject: Time From: J D Cooley cooleyj@.................... Date: Mon, 19 Aug 2002 20:05:13 -0700 I have been following the discussion about accurate time for PCs. I'm at work right now, but at home I have 4 or 5 programs that get the "exact" time and update my computer, if I want. I don't have the need for extremely accurate time, but the programs are interesting to use. My main question is: which one is correct? I think all of them have their time based on the atomic clocks at NIST, but I can switch from one program to another and see a difference between them of up to nearly one second. How does one know which one is the most accurate? I'm sure at least two of the programs I use will first ping the server they are getting the time from to get the delay, which seems necessary. The radio I used to use to listen to WWV is broken, but perhaps that would be a good way to find out which programs are WAY off! "JD" Cooley San Diego County __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Time From: Keith Payea kpayea@........... Date: Mon, 19 Aug 2002 21:00:07 -0700 The thing to look for is a time client that uses the full NTP spec. It uses four time stamps to calculate the transmission times so that they can be factored out of the time. Many free clients use Simple NTP, which doesn't use all four time stamps. A crucial part of NTP is also in the filtering. A good client will make many requests (up to once every 64 seconds) and filter the results over time. With a one-shot time request, an offset of 1 second isn't surprising. Most of them will give better performance if you run them for a while. I work for TrueTime, and we make Network Time Servers which synchronize to GPS and then provide NTP to a network. If you go to this page, you can download a free time client we have called WinSync. You have to register for it, but they won't bug you much. Here's the link: http://www.truetime.net/software-winsync.html Another excellent site is the home of NTP at the University of Delaware: http://www.eecis.udel.edu/~ntp/ Cheers, Keith Keith Payea kpayea@........... ----- Original Message ----- From: "J D Cooley" To: Sent: Monday, August 19, 2002 8:05 PM Subject: Time > I have been following the discussion about accurate time for PCs. I'm at > work right now, but at home I have 4 or 5 programs that get the "exact" > time and update my computer, if I want. I don't have the need for > extremely accurate time, but the programs are interesting to use. > > My main question is: which one is correct? I think all of them have their > time based on the atomic clocks at NIST, but I can switch from one program > to another and see a difference between them of up to nearly one > second. How does one know which one is the most accurate? I'm sure at > least two of the programs I use will first ping the server they are getting > the time from to get the delay, which seems necessary. > > The radio I used to use to listen to WWV is broken, but perhaps that would > be a good way to find out which programs are WAY off! > > "JD" Cooley > San Diego County > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Time From: J D Cooley cooleyj@.................... Date: Mon, 19 Aug 2002 21:22:53 -0700 Thank you, Keith. I'm sure this is the type of information that the others on this list are needing. I will check it out when I get home and have internet access! "JD" Cooley San Diego County At 09:00 PM 8/19/02, Keith Payea wrote: >The thing to look for is a time client that uses the full NTP spec. It uses >four time stamps to calculate the transmission times so that they can be >factored out of the time. Many free clients use Simple NTP, which doesn't >use all four time stamps. > >A crucial part of NTP is also in the filtering. A good client will make >many requests (up to once every 64 seconds) and filter the results over >time. With a one-shot time request, an offset of 1 second isn't surprising. >Most of them will give better performance if you run them for a while. > >I work for TrueTime, and we make Network Time Servers which synchronize to >GPS and then provide NTP to a network. If you go to this page, you can >download a free time client we have called WinSync. You have to register >for it, but they won't bug you much. Here's the link: >http://www.truetime.net/software-winsync.html > >Another excellent site is the home of NTP at the University of Delaware: >http://www.eecis.udel.edu/~ntp/ > >Cheers, > > Keith > > >Keith Payea >kpayea@........... > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: A Request From: "Connie and Jim Lehman" lehmancj@........... Date: Tue, 20 Aug 2002 18:44:52 -0400 As for sensing microseisms by laser, several years ago we attempted to = use a laser beam and photocells as a shortcut to seismic copy. In = setting up the system, we bounced the beam off of front surface mirrors = for a total length of 500 ft or so. By using a one-half milliwatt = standard laboratory laser, the beam enlarged to about the size of a = tennis ball. The system was very sensitive, and we thought at that time = we were seeing only the mechanical vibrations of the building--we were = at ground lever on a gravel floor in an unused part of the science = building. Other interests took us elsewhere, and we never pursued this = further. J. Lehman Virginia, USA=20
As for sensing microseisms by = laser,=20 several years ago we attempted to use a laser beam and photocells as a = shortcut=20 to seismic copy.  In setting up the system, we bounced the beam off = of=20 front surface mirrors for a total length of 500 ft or so.  = By using a=20 one-half milliwatt standard  laboratory laser, the beam enlarged to = about=20 the size of a tennis ball.  The system was very sensitive, and we = thought=20 at that time we were seeing only the mechanical vibrations of the=20 building--we were at ground lever on a gravel floor in an unused part of = the=20 science building.  Other interests took us elsewhere, and we never = pursued=20 this further.
          &nbs= p;            = ;            =          =20 J. Lehman
          &nbs= p;            = ;            =              = Virginia, USA 
Subject: Re: A Request From: John C Cole johncole4@........ Date: Thu, 22 Aug 2002 11:43:45 -0500 Rolando,When Frank said,that he had never seen such an outstanding job of editing of a posting , He was saying that he had never seen so much data removed from an event to make it look better. Frank said that it was the worst that he had ever seen posted . Frank took his posting ,mine and several others and re edited them to where they showed an astronomical time just like our friend . All that glitters is not gold. We were deceived . It could have been intentional or perhaps, unintentional ? He discarded all the seismic frequencies with the exception of the very low ones and that left very little in the event . Send the mailing address again . I have lost it. JC ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/web/. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: A Request From: ChrisAtUpw@....... Date: Fri, 23 Aug 2002 22:55:46 EDT In a message dated 22/08/02, johncole4@........ writes: > Rolando,When Frank said,that he had never seen such an outstanding job of > editing of a posting , He was saying that he had never seen so much data > removed from an event to make it look better. Hi John, It would be great to know what posting you were referring to. There are two good reasons for going to very low frequencies: You may want to cut out man made noise. If you have severe wind / weather noise, you may need to reduce the frequency quite a bit further. Very long period responses are available. The Lamont-Doherty Cooperative Seismographic Network (LCSN) springs to mind. Do these considerations apply? Regards, Chris Chapman In a message dated 22/08/02, johncole4@........ writes:

Roland o,When Frank said,that he had never seen such an outstanding job of
editing of a posting , He was saying that he had never seen so much data
removed from an event to make it look better.


Hi John,

      It would be great to know what posting you were referring to.

      There are two good reasons for going to very low frequencies:
      You may want to cut out man made noise.
      If you have severe wind / weather noise, you may need to reduce the frequency  &n bsp;   quite a bit further.
      Very long period responses are available. The Lamont-Doherty Cooperative Seismographic Network (LCSN) springs to mind.
      Do these considerations apply?

      Regards,

      Chris Chapman
Subject: RE: A Request From: "Rolando Benitez" rbenitez@........ Date: Sat, 24 Aug 2002 21:42:32 -0600 Hello Chris, What is the purpose of posting events at the PSN web page? Should we post the raw data or an edited file? What should be the goal when filtering? I am almost new in the list, a very ignorant one. Your comments on this subject would be very appreciated. Best regards, Rolando Benitez Fraijanes, Guatemala It would be great to know what posting you were referring to. There are two good reasons for going to very low frequencies: You may want to cut out man made noise. If you have severe wind / weather noise, you may need to reduce the frequency quite a bit further. Very long period responses are available. The Lamont-Doherty Cooperative Seismographic Network (LCSN) springs to mind. Do these considerations apply? Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: A Request From: "Larry Cochrane" cochrane@.............. Date: Sat, 24 Aug 2002 20:55:59 -0700 Rolando, I'll answer your question. Event files should not be filtered or integrated, just send the raw data. This way others can apply different filters etc. Also, there should be a few minutes of data before the event and a few minutes of data after the event so that programs like WinQuake can figure out the noise level before and after the event. This is used to calculate the Md or Coda magnitude of the event. Regards, Larry Cochrane Redwood City, PSN ----- Original Message ----- From: "Rolando Benitez" To: Sent: Saturday, August 24, 2002 8:42 PM Subject: RE: A Request > Hello Chris, > What is the purpose of posting events at the PSN web page? Should we post > the raw data or an edited file? What should be the goal when filtering? > I am almost new in the list, a very ignorant one. Your comments on this > subject would be very appreciated. > Best regards, > > Rolando Benitez > Fraijanes, Guatemala > > > It would be great to know what posting you were referring to. > > There are two good reasons for going to very low frequencies: > You may want to cut out man made noise. > If you have severe wind / weather noise, you may need to reduce the > frequency quite a bit further. > Very long period responses are available. The Lamont-Doherty > Cooperative Seismographic Network (LCSN) springs to mind. > Do these considerations apply? > > Regards, > > Chris Chapman > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: A Request From: "Rolando Benitez" rbenitez@........ Date: Sat, 24 Aug 2002 22:30:38 -0600 Larry, Thank you very much for your msg and for answering one of my questions. Best regards, Rolando ...-----Original Message----- ...From: psn-l-request@.............. ...[mailto:psn-l-request@................. Behalf Of Larry Cochrane ...Sent: Saturday, August 24, 2002 9:56 PM ...To: psn-l@.............. ...Subject: Re: A Request ... ... ...Rolando, ... ...I'll answer your question. Event files should not be filtered or ...integrated, ...just send the raw data. This way others can apply different filters etc. ...Also, there should be a few minutes of data before the event and a few ...minutes of data after the event so that programs like WinQuake can figure ...out the noise level before and after the event. This is used to calculate ...the Md or Coda magnitude of the event. ... ...Regards, ...Larry Cochrane ...Redwood City, PSN ... ...----- Original Message ----- ...From: "Rolando Benitez" ...To: ...Sent: Saturday, August 24, 2002 8:42 PM ...Subject: RE: A Request ... ... ...> Hello Chris, ...> What is the purpose of posting events at the PSN web page? ...Should we post ...> the raw data or an edited file? What should be the goal when filtering? ...> I am almost new in the list, a very ignorant one. Your comments on this ...> subject would be very appreciated. ...> Best regards, ...> ...> Rolando Benitez ...> Fraijanes, Guatemala ...> ...> ...> It would be great to know what posting you were referring to. ...> ...> There are two good reasons for going to very low frequencies: ...> You may want to cut out man made noise. ...> If you have severe wind / weather noise, you may need to ...reduce the ...> frequency quite a bit further. ...> Very long period responses are available. The Lamont-Doherty ...> Cooperative Seismographic Network (LCSN) springs to mind. ...> Do these considerations apply? ...> ...> Regards, ...> ...> Chris Chapman ...> ...> __________________________________________________________ ...> ...> Public Seismic Network Mailing List (PSN-L) ...> ...> To leave this list email PSN-L-REQUEST@.............. with ...> the body of the message (first line only): unsubscribe ...> See http://www.seismicnet.com/maillist.html for more information. ...> ... ... ...__________________________________________________________ ... ...Public Seismic Network Mailing List (PSN-L) ... ...To leave this list email PSN-L-REQUEST@.............. with ...the body of the message (first line only): unsubscribe ...See http://www.seismicnet.com/maillist.html for more information. ... ... ... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Scientific American - The Amateur scientist From: Arie Verveer ajbv@............ Date: Sun, 25 Aug 2002 10:12:14 +0000 Hi, Recently I purchased a complete collection of the "Amateur Scientist" articles on CD ROM. That's from 1920 to 2000. It a has all the articles on seismology. Ever read the article's April 1952, June 1953 ( a goodie), July 1957, Nov. 1973, Sept. 1975, July 1979, April 1996 just look under earth sciences. If you are interested : http://www.tinkersguild.com/ Fun for all at a cheap price. Cheers Arie __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Infrasound..Web page upgrade..Seismograph Chat.. Locating a earthquake From: Arie Verveer ajbv@............ Date: Sun, 25 Aug 2002 10:55:10 +0000 Hi, For the late month or so I've been testing a "Infrasound" detector built using inspiration from these two articles: The Geophysical Journal of the Royal Astronomical Society, Vol. 26 Belljar :- http://www.tiac.net/users/shansen/beljar/microbar.htm Though the reference to the "Belljar" HTML link has now been closed down. Anyone know where its gone?? I would like to write to the author. Anyhow, I'm automatically posting the filtered data to my web site at: http://www.iinet.net.au/~ajbv At present the data is filtered from 0.5 to 10 hertz, but this is experimental and can be easily changed. (Looking for fireball re-entries). What I would like to do is detect and quake and its associated Rayleigh waves, a tall order. But I can wait a few years. Well I hope I can wait a few years. Any suggestions on the best frequency bands to detect micro pressure waves associated from quakes? If you find the trace full of noise then you can be guaranteed that its windy. Wind and its turbulence is a big problem. My web site also has a simple article on locating an earthquake using 3 methods that might be of interest. Plus some software upgrades. Here is a thought. The differential pressure sensors used in the Infrasound experiment would make an interesting detector for a tilt meter. A sealed system, with two chambers half filled with a viscous oil and the differential pressure sensor monitoring the pressure changes in the air above the oil. Thus a tube between the oil chambers and a air return from each chamber to the sensor. I bet it would work. Cheers Arie __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Infrasound..Web page upgrade..Seismograph Chat.. Locating From: Chuck Erickson cee@............. Date: Sun, 25 Aug 2002 07:18:33 -0700 Arie, Is this it? http://www.belljar.net/microbar.htm Chuck At 10:55 AM 8/25/2002 +0000, you wrote: >Hi, For the late month or so I've been testing a "Infrasound" detector >built using inspiration from these two articles: > > The Geophysical Journal of the Royal Astronomical Society, Vol. 26 > Belljar :- http://www.tiac.net/users/shansen/beljar/microbar.htm > >Though the reference to the "Belljar" HTML link has now been closed down. >Anyone know where its gone?? I would like to write to the author. .....snip.... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Scientific American - The Amateur scientist From: "Larry Conklin" lconklin@............ Date: Sun, 25 Aug 2002 11:20:57 -0400 Good greif! I paid about 5 times that much for that CD when it was first released. Thought it was a little pricey at the time, but I loved the original Amateur Scientist column so I thought it was worth it. I still think it's a great collection, especially at the new very reasonable price. Larry Conklin lconklin@............ ----- Original Message ----- From: "Arie Verveer" To: Sent: Sunday, August 25, 2002 6:12 AM Subject: Scientific American - The Amateur scientist > Hi, Recently I purchased a complete collection of the "Amateur > Scientist" articles on CD ROM. That's from 1920 to 2000. It > a has all the articles on seismology. Ever read the article's > April 1952, June 1953 ( a goodie), July 1957, Nov. 1973, Sept. 1975, > July 1979, April 1996 just look under earth sciences. > > If you are interested : http://www.tinkersguild.com/ > > Fun for all at a cheap price. > > Cheers > > Arie > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Infrasound.. From: Hammonds hammond@........... Date: Sun, 25 Aug 2002 08:30:33 -0800 Arie, here's some links I've collected on infrasound equipment and use. I used to work with some of the people described in these links. I've been thinking of building one. http://geology.about.com/library/weekly/aa121497.htm http://www.polar.org/antsun/oldissues2000-2001/2001_0204/ctbto.html http://www.nemre.nn.doe.gov/nemre/introduction/infrasound_fact_sheet.html http://www.nemre.nn.doe.gov/nemre/introduction/infrasound_mon2.html http://www.pidc.org/rdss/resources/INFRA/doc/2_Stations.htm http://geology.heroy.smu.edu/~hayward/Projects/Infrasonics/assets/sow.html http://www.seismo.berkeley.edu/seismo/annual_report/ar99_00/node11.html#SECTION03740000000000000000 and of course http://www.belljar.net/microbar.htm regards, Bob Hammond Alaska Public Seismic Network http://apsn.awcable.com At 02:55 AM 8/25/2002, you wrote: >Hi, For the late month or so I've been testing a "Infrasound" detector >built using inspiration from these two articles: > > The Geophysical Journal of the Royal Astronomical Society, Vol. 26 > Belljar :- http://www.tiac.net/users/shansen/beljar/microbar.htm > >Though the reference to the "Belljar" HTML link has now been closed down. >Anyone know where its gone?? I would like to write to the author. >Anyhow, I'm automatically posting the filtered data to my web site at: > >http://www.iinet.net.au/~ajbv > >At present the data is filtered from 0.5 to 10 hertz, but this is experimental >and can be easily changed. (Looking for fireball re-entries). What I >would like >to do is detect and quake and its associated Rayleigh waves, a tall order. >But I can wait a few years. Well I hope I can wait a few years. Any >suggestions >on the best frequency bands to detect micro pressure waves associated from >quakes? If you find the trace full of noise then you can be guaranteed >that its >windy. Wind and its turbulence is a big problem. > >My web site also has a simple article on locating an earthquake using 3 >methods >that might be of interest. Plus some software upgrades. > >Here is a thought. The differential pressure sensors used in the Infrasound >experiment would make an interesting detector for a tilt meter. A sealed >system, >with two chambers half filled with a viscous oil and the differential pressure >sensor monitoring the pressure changes in the air above the oil. Thus a >tube between >the oil chambers and a air return from each chamber to the sensor. I bet >it would >work. > > >Cheers > >Arie >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Infrasound From: ChrisAtUpw@....... Date: Sun, 25 Aug 2002 19:42:27 EDT In a message dated 25/08/02, ajbv@............ writes: > What I would like to do is detect a quake and its associated Rayleigh waves, > a tall order. But I can wait a few years. Hi Arie, You can make a sensitive Infrasonic system using a 50 mm piezo speaker as the sensor element and a TLC2201 low noise opamp + some filtering. You need a very high input impedance and you need to control the temperature of the PZT element. It can be a help to use a pneumatic low pass filter on the input. The original infrasound sensors used a brass bellows about 2.5" dia with a free armature LVDT sensor on the closed end. One of the Schaevitz HR 050 LVDT sensors would be suitable, coupled up to a NE5521 LVDT chip. It is also possible to use a NE5521 chip with an additional CMOS input amplifier with a moving diaphragm, either of aluminised mylar or of Al, SS or Brass foil. The twin input electrodes on either side of the diaphragm may need to be made of mesh or have a lot of holes in them, so as not to severely air damp the motion of the diaphragm. Any suggestions on the best frequency bands to detect micro pressure waves > associated from quakes? How about the same frequency as the quakes? You might consider surround lengths of plastic tube to provide some directional sensitivity. > > windy. Wind and its turbulence is a big problem. The American systems seem to use either micro porous irrigation tube as shown in the photos or rigid plastic tube with restricting plugs every few feet. The fine tubes in the restricting plugs need to be protected from insects and from dust. As far as I know, elliptical section silicone rubber tubes have not been tried. The published layouts show radiating tubes. Hexagonal or circular plan arrays with connecting tubes to a central sensor have also been used successfully. These may be over 100 ft in dia and average out small scale turbulence quite well. Tubing may be installed in shallow covered trenches just below soil level, to reduce wind noise. Let me know if you want any further info or references. Regards, Chris Chapman In a message dated 25/08/02, ajbv@............ writes:

What I would like to do is detect a quake and its associated Rayleigh waves, a tall order. But I can wait a few years.


Hi Arie,

      You can make a sensitive Infrasonic system using a 50 mm piezo speaker as the sensor e lement and a TLC2201 low noise opamp + some filtering. You need a very high input impedance and you need to control the tempera ture of the PZT element. It can be a help to use a pneumatic low pass filter on the input.

      The original infrasound sensors used a brass bellows about 2.5" dia with a free armatu re LVDT sensor on the closed end. One of the Schaevitz HR 050 LVDT sensors would be suitable, coupled up to a NE5521 LVDT chip.

      It is also possible to use a NE5521 chip with an additional CMOS input amplifier with a moving diaphragm, either of aluminised mylar or of Al, SS or Brass foil. The twin input electrodes on either side of the diap hragm may need to be made of mesh or have a lot of holes in them, so as not to severely air damp the motion of the diaphragm.

      Any suggestions on the best frequency bands to detect micro pressure waves

Arie, here's some links I've collected on infrasound equipment and use. I >used to work with some of the people described in these >links. I've been thinking of building one. > >http://geology.about.com/library/weekly/aa121497.htm >http://www.polar.org/antsun/oldissues2000-2001/2001_0204/ctbto.html >http://www.nemre.nn.doe.gov/nemre/introduction/infrasound_fact_sheet.html >http://www.nemre.nn.doe.gov/nemre/introduction/infrasound_mon2.html >http://www.pidc.org/rdss/resources/INFRA/doc/2_Stations.htm >http://geology.heroy.smu.edu/~hayward/Projects/Infrasonics/assets/sow.html >http://www.seismo.berkeley.edu/seismo/annual_report/ar99_00/node11.html#SECTION03740000000000000000 > >and of course http://www.belljar.net/microbar.htm > >regards, > >Bob Hammond >Alaska Public Seismic Network >http://apsn.awcable.com Jim Hannon http://www.fmtcs.com/web/jmhannon 42,11.90N,91,39.26W WB0TXL __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Outage using PSN.QUAKE.NET From: John & Jan johnjan@........ Date: Sun, 25 Aug 2002 22:04:53 -0600 Hi Larry, On your PSN page, could up change the following link for the Golden PSN from http://lahr.org/john-jan/psn/gldn_psn.html to http://jjlahr.com/science/psn/ Thanks, John John C. Lahr 1925 Foothills Road Golden, CO 80402 Phone: (303) 215-9913 john@........ http://jjlahr.com/science __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Outage using PSN.QUAKE.NET From: Stephen & Kathy skmort@.......... Date: Sun, 25 Aug 2002 21:45:06 -0700 WOW,,, NOW THAT IS CUTE!!!!!!!!!! ha ha ha If you haven't been to his new site yet, you need to go!!! ha ha ha Stephen 38.828N 120.979W John & Jan wrote: > > Hi Larry, > > On your PSN page, could up change the following link for the Golden PSN from > http://lahr.org/john-jan/psn/gldn_psn.html > to > http://jjlahr.com/science/psn/ > > Thanks, > John > > John C. Lahr > 1925 Foothills Road > Golden, CO 80402 > Phone: (303) 215-9913 > john@........ > http://jjlahr.com/science > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: classroom seismology From: John Taber taber@........ Date: Mon, 26 Aug 2002 17:59:45 -0400 Some of you may remember a few years ago when Ted Blank and Jan Froom brought a group of students to the fall AGU meeting in San Francisco to present their earthquake monitoring results. The afternoon was a great success both for the students and the many seismologists who stopped to talk to the students about their poster (see Ted Blank's report below). There is going to be a session at this year's AGU (Dec 6-10) called "Geophysics data in the classroom" and it would be a perfect chance for the same and/or more schools to get involved. AGU has just agreed to waive the abstract submission fee and the 1-day registration fee for the meeting so the only cost would be the creation of the poster and transporation to the meeting. I'm attached a copy of the session description below. Abstracts are due 14:00 UTC on Sept 5, so there isn't much time to prepare them, but they can be short (and no longer than 2600 characters). For more information about abstract submission, see the AGU website www.agu.org. Please contact me or send email to the PSN list if you think you might be interested or know of a school that might like to take part. Special AGU session ED05 - Geophysics Data in the Classroom Programs that encourage students to make observations of the oceans, the atmosphere or the solid earth offer the opportunity to capture a student's innate curiosity for natural phenomena, and this curiosity can be used as a platform from which a wealth of fundamental principles of physics and Earth sciences can be taught. Such programs also offer the research community opportunities to develop geophysical research networks in areas otherwise not feasible. A number of new initiatives are working to foster improved communication between academic researchers, college faculty, and secondary and middle school teachers to help students utilize geophysical data in a wide variety of educational settings. The educational geophysics movement also extends across national borders, with programs in Europe, North and South America, and the Pacific Rim. This session welcomes presentations on all aspects of educational geophysics, including classroom activities, university-school partnerships, local networks, educational software, and low-cost instrumentation. Presentations from university and high school teachers and students are particularly encouraged. ` John Taber E&O Program Manager Tel: 202-682-2220 IRIS Fax: 202-682-2444 1200 New York Ave., NW, Suite 800 Email: taber@........ Washington, DC 20005 From the PSN archives: >Date: Sat, 12 Dec 1998 00:00:10 -0800 >From: Ted Blank >Subject: >To: psn-l@.............. > >Today at the Fall Meeting of the AGU, Jan Froom and I "presented" poster >session U42A-27 entitled "Seismic Monitoring in the Classroom - A >Complement to the Traditional Middle School Earth Science Curriculum." I >have placed the word "presented" in quotes because Jan and I actually did >no presenting at all. All the hard work was done by a group of 12 highly >motivated and skilled young scientists from our two local schools. These >kids did an absolutely incredible job of explaining their involvement with >seismology in the classroom. They patiently explained to anyone who >stopped by about how to analyze a seismogram to identify P and S wave >arrivals, how to calculate distance to the epicenter, what plate tectonics >was all about, how the structure of the earth can be examined by studying >earthquakes, and how to use the Seismic Long wave In-situ New Knowledge >for Youth (S.L.I.N.K.Y.) device to demonstrate modes of wave propagation >through the earth. They are all apparently expert at operating WinQuake as >well! They worked in pairs for 30 minutes each and then spent the rest of >the time touring the many hundreds of posters being presented on every >subject under the sun. When one girl asked me what "correlation" meant I >knew that at least one of the kids was really reading the posters! Many >kids came back during their "off" time to help out their friends. > >We received lots of positive comments about the kids from numerous folks. >Representatives from IRIS and the AGU Outreach Education project were >among them. This is a testament to the professional job these young people >did all day. Many grey-haired seismologists got refresher courses in >Seismo 101, and most stayed more than 5-10 minutes which is a actually >quite a long time given how many other posters compete for your attention. > >Many thanks again to Ed Cranswick for sponsoring this session and fighting >all the battles with AGU. Larry Cochrane rescued our Internet connection >and downloaded a copy of WinQuake on the fly (to bail out some dummy who >forgot to bring the disk). John Taber, our next door poster neighbor, >helped out a lot. We look forward to hooking up with the New Zealand >Quake Trackers. Teachers and parents from both schools came along and >chaperoned the kids around when they weren't presenting (not that they >needed it). Thanks to you all. > >We met Alan Jones as well, which was a real treat. I've known Alan for >many years (he's a former IBMer) but only met once long ago. Alan is the >author of the Seismic/Eruption and Seismic Waves programs which are used by >many news stations nationwide as well as having a prominent place in the >new earth science display at the Smithsonian Museum of Natural History in >Washington, D.C. He was very gracious and let the kids re-educate him on >seismology from the ground up. > >The comments from our kids on the way home said it all. They wanted to >know if there were any more of these meetings soon, and could they come for >an entire week next time! > >Ted Blank >San Jose, California > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: New Station Questions From: "Jonathan Peakall" jpeakall@............ Date: Tue, 27 Aug 2002 06:56:23 -0700 Hi All, I'm new to seismology. Spent a while looking through the archives. Whew! A little intimidating! I looked for a newsgroup more oriented to beginners, but no luck. If these questions are too basic for this group, let me know where I might ask them, if you can. A little background: I am a science teacher in a small rural elementary school. As part of an Earth Science unit I am developing, I have made a simple seismic station. My goal is to be able to record events, determine magnitude and use the data to determine location and time of origin. Accuracy of wave form depiction is not that important, just time and magnitude. Station specs: 2 sec pendulum style sensor (NIB magnets suspended over a 1.1kOhm buzzer coil) Dampening: small sheet of brass between the magnet and the coil 741 op amp amplifier DATAQ 194RS A/D board 133 mHz laptop to log WWVB clock with photo diode pickup (puts minute marks into log) The sensor is very sensitive to local events. Background noise seems OK. I could detect logging activity a couple of miles away (trees hitting the ground look very different from seismic activity). Jumping in my house 50' away is visible if magnified, and dropping a rock nearby is huge. So, onto the questions: 1) What is the average sample rated used by stations? 2) What level of compression is usually used to examine results? 3) Where can I find information to determine an ideal or reasonable level of dampening? 4) How can I convert magnitude to UG or MM? 5) Does anyone know of quakeware that will work with this A/D board? Sample rate/compression/signal amplification and dampening are obviously related in trying to examine the wave form. Is there a formula, rule of thumb, or does one tweak the system till it "looks right"? Larry Cochrane has been very helpful, and says that if my sensor is usefully sensitive, I should be able to record quakes that he detects in Redwood City (289 kms as the crow flies from me) of magnitude 3.5 or greater. His web site shows the events in mg and cm's (actually, I thought it was ug and mm' s, but I just looked). How can I convert these figures to magnitude? I just need a way to figure out when Larry's site is showing an event that I should have picked up. I have seen some Geosource model MD-31 geophone sensor for sale cheap. Anyone know if these are useful in my application? Frequency wasn't stated. Unfortunately, price is a major restriction for me, so buying a nice sensors is out of the question. I am going to build a Leham type at some point, but part of the fun is going to be the students building the sensor for their station, so I am committed to the pendulum style (due to ease of construction) unless it is absolutely useless. Thanks for your time! Jonathan Peakall www.madlabs.info __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: New Station Questions From: John & Jan johnjan@........ Date: Tue, 27 Aug 2002 09:30:13 -0600 Dear Jonathan, It's great that you've set up a seismograph station in your school!!! There is a national effort to promote school-based seismic recording which is supported by the NSF through IRIS and the USESN US Educational Seismograph Network . Your efforts and feedback to these groups would be very helpful to the effort. At 06:56 AM 8/27/2002 -0700, you wrote: >So, onto the questions: > >1) What is the average sample rated used by stations? This relates to the sensor period and the type of earthquake that one wants to record. For local events a sensor with a natural frequency of 1 to 2 Hz is ideal and sample rates of 50 Hz to 100 Hz are typically used. Keep in mind that a filter is required prior to the AD that will eliminate frequencies above the Nyquist frequency which is one half of the sampling frequency. For recording distant (teleseismic) events a sensor with a period of about 15 - 20 seconds is good because the surface waves have a lot of energy in this range. Due to limited dynamic range the higher frequencies are often filtered out from a long-period system, so a high cut filter might be set to 1 Hz and the sampling rate set to 6 Hz. >2) What level of compression is usually used to examine results? I'm not sure what your question is. >3) Where can I find information to determine an ideal or reasonable level of >dampening? Dampening is usually set to a bit less than critical. For all the details, see: Roughly what you want when the pendulum is bumped is for it to reach a peak, return past zero to another peak and then return to zero with very little overshoot. >4) How can I convert magnitude to UG or MM? If you system is calibrated so that you know what the peak amplitude is in microns for a local event, then you can use Richter's original magnitude formula to estimate the magnitude. See: >5) Does anyone know of quakeware that will work with this A/D board? You could try the AmaSeis program written by Alan Jones. It works with the DI154RS Dataq AD but I'm not sure about the DI194RS unit. See Alan web site for this an two other free programs for seismology education. Best of luck with your seismology. Cheers, John John C. Lahr 1925 Foothills Road Golden, CO 80402 Phone: (303) 215-9913 john@........ http://jjlahr.com/science __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: New Station Questions From: "Jonathan Peakall" jpeakall@............ Date: Wed, 28 Aug 2002 08:22:24 -0700 John, Wow, neat stuff. I took a brief look, will look in depth soon. Sounds like a great project! > It's great that you've set up a seismograph station in your > school!!! There is a > national effort to promote school-based seismic recording which is supported by > the NSF through IRIS > and the USESN > US Educational Seismograph Network . > Your efforts and feedback to these groups would be very helpful to the effort. > > > At 06:56 AM 8/27/2002 -0700, you wrote: > >So, onto the questions: > > > >1) What is the average sample rated used by stations? > This relates to the sensor period and the type of earthquake that one wants > to record. For local events a sensor with a natural frequency of 1 to 2 Hz is > ideal and sample rates of 50 Hz to 100 Hz are typically used. Keep in mind > that a filter is required prior to the AD that will eliminate frequencies above > the Nyquist frequency > > which is one half of the sampling frequency. > All new to me. Great page about Nyquist stuff. Still digesting it, but is the bottom line to keep my sample rates above the Nyquist frequency, right? > For recording distant (teleseismic) events a sensor with a period of about > 15 - 20 > seconds is good because the surface waves have a lot of energy in this range. > Due to limited dynamic range the higher frequencies are often filtered out from > a long-period system, so a high cut filter might be set to 1 Hz and the > sampling > rate set to 6 Hz. > I live in northern CA, about 289kms from Larry's site in Redwood City. My goal is to make a system sensitive enough to record moderate quakes that Larry does. If we get a hit or two a week, that would be fine. So should I be able to do this with a 2 sec pendulum sensor of reasonable functionality? > > >4) How can I convert magnitude to UG or MM? > > If you system is calibrated so that you know what the peak amplitude > is in microns for a local event, then you can use Richter's original > magnitude formula to estimate the magnitude. See: > > The main thing I want to do is to be able to use Larry's site to check my system. His site shows the most recent/largest event in accelration units. I want to be able to convert that to magnitude, or otherwise know when Larry has recorded and event that I should have. Thanks for the help! Jonathan Peakall __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: New Station Questions From: John & Jan johnjan@........ Date: Wed, 28 Aug 2002 19:55:16 -0600 At 08:22 AM 8/28/2002 -0700, you wrote: >The main thing I want to do is to be able to use Larry's site to check my >system. His site shows the most recent/largest event in accelration units. I >want to be able to convert that to magnitude, or otherwise know when Larry >has recorded and event that I should have. > >Thanks for the help! > >Jonathan Peakall Hi Johathan, Another way to check if you should have recorded an event would be to enter your coordinates into this page: >http://geohazards.cr.usgs.gov/tt/artim.html Then you can search for recent events within, say 5 degrees (555 km). The arrival time of P and S are given so you will know exactly where to look for the event on your seismogram. A pendulum with 2 second period should be fine for this. You will probably want to sample at perhaps 20 Hz and filter out frequencies above 10 Hz prior to the AD. Another site to use for finding recent earthquakes is: http://earthquake.usgs.gov/ I've ordered a DI194RS unit so will know in a few weeks if it will work with Alan Jones' AmaSeis software. Cheers, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Infrasound From: Arie Verveer ajbv@............ Date: Thu, 29 Aug 2002 13:19:21 +0000 Hi, Thanks for all the links to the Infrasound data, it was rather helpful. After a read it turns out that the international monitoring system (IMS) sets their optimal frequency range from 0.03 to around 3 Hz. I would assume this is to monitor Infrasound air bursts and hence it may be useful in the detection of fireball re-entry's. One other paper suggests the earthquake Rayleight waves are in the 0.125 to 0.0125 hertz range. That is a period of 8 to 80 seconds. My infrasound detector has now been set to display a report in the 0.03 - 2.0 Hertz range. Though the raw data is still in the DC to 10 Hertz range. It uses post digital filtering. Cheers and thanks for the info. By the way the next few days its going to be windy hear, so the detector will shows noise. Cheers Arie __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismograph From: Ed Ianni eianni2@........... Date: Thu, 29 Aug 2002 20:26:26 -0400 I am interested in taking my homemade Lehman Seismograph and feeding it into my computer to look at the data online and to store it for later review. I am looking for a simple system to do this. Can you guide me a little bit? Can I use my sound card as an AD converter? Is there a simple program on the web that well let me see it ONLINE and also STORE it? Thanks a lot. Ed.
 
 

     I am interested in taking my homemade Lehman Seismograph and feeding it into my computer to look at the data online and to store it for later review. I am looking for a simple system to do this. Can you guide me a little bit? Can I use my sound card as an AD converter? Is there a simple program on the web that well let me see it ONLINE and also STORE it? Thanks a lot. Ed.   
Subject: Fwd: EPICS Charge to students From: John & Jan johnjan@........ Date: Thu, 29 Aug 2002 18:49:38 -0600 This semester at the Colorado School of Mines all 350 freshmen will be=20 working on the design of an inexpensive seismic system. They will be divided into 70=20 groups of 5 for this effort. Because the goal is to design an inexpensive instrument (less= =20 than $150) some things may have to be sacrificed, including linearity and single-axis= =20 sensitivity. The $150 limit (exclusive of a PC) would make this instrument a candidate=20 for the GLOBE program, an educational program with international scope and many collaborators that is currently focused on weather, atmosphere, and=20 biology issues. I will encourage the students to join mailing lists, such as this one, to= =20 get information and advice for their projects. The PSN group collectively has a wealth of= =20 experience that they could benefit from. A letter with added details follows. Cheers, John >August 20, 2002 >Robert D. Knecht >Colorado School of Mines > >Dear Dr. Knecht, > >The IRIS Consortium Education and Outreach Committee is pleased that the=20 >EPICS Project for this >year will be the design of an inexpensive sensor for seismic=20 >waves. Computers, which are widely >available in K-16 classrooms, have replaced the paper-drum and pen=20 >recorders of earlier years. >IRIS has sponsored the development of AmaSeis, a free, PC-based program=20 >that monitors the real- >time stream of data from a seismometer so that near and distant=20 >earthquakes can be easily recorded >and viewed graphically. > >The principal remaining barrier to more widespread, school-based=20 >earthquake recording systems is >the availability of an inexpensive, yet sensitive, long-period seismic=20 >sensor that can attach to a PC's >serial port via an analog-to-digital converter. > >The least expensive commercially available system (excluding the PC) costs= =20 >about $500, which >precludes purchase by very many teachers or schools. If this cost could=20 >be reduced to $150 or less, >it would be within the range of many more budgets and would also be a good= =20 >candidate to become >an instrument recommended for use by the Globe=20 >program. > >Design Goals and Options > >Sensitivity > >For the system to be useful in any location on the Earth, it must be able= =20 >to record large earthquakes >at any distance -- teleseisms in the terminology of seismologists. This=20 >requires a good signal to >noise ratio in the period range from 1 to 20 seconds. > >The following table gives a rough idea of the amplitude and velocity of=20 >ground motion that would >be expected from a magnitude 7 earthquake at 90 and 180 degrees distance. > >Magnitude 7 at 90 degrees distance: amplitude velocity >Expected 20s period surface wave amplitude [ 5.61E+01 =B5m] [ 1.76E+01= =B5m/s] >Expected 1s period body wave amplitude [ 7.93E-01 =B5m] [ 4.98E+00= =B5m/s] > >Magnitude 7 at 180 degrees distance: >Expected 20s period surface wave amplitude [ 1.81E+01 =B5m] [ 5.68E+00= =B5m/s] >(No direct P-phase at this distance.) > >Construction Strategy > >One strategy might be to look at commercially available recording systems,= =20 >such as the AS1 > on display at CSM, the Sprengnether >, and the designs of=20 >the Public Seismic >Network and >. Explore ways in which the=20 >cost of manufacture, and >hence, the cost of purchase of these instruments could be reduced by=20 >eliminating expensive or >carefully machined components. > >Either a high-school teacher with little or no mechanical and fabrication= =20 >skill should be able to >build one from scratch for about $150, or, if you choose to reduce costs=20 >by distributing instruments >in kit form, the cost to the fabricator must be such that an=20 >easily-assembled kit will sell for less than >$150. > >Sensor > >The sensor could be based on the voltage generated by relative motion=20 >between a coil and magnet, >on the proximity of a magnet to a Hall-effect sensor, on the amount of=20 >light reaching a photo diode >that is partially blocked by a flag, on the strain of a piezoelectric=20 >crystal, or on the output of a micro >machined accelerometer similar to those used to trigger the release of an= =20 >automobile's air bag. >Given that new, high-density, low-cost disk drives are continually coming= =20 >to market, there may >well be some sophisticated, mass-produced, and yet inexpensive components= =20 >that could also be >used for this application. > >Recording Options > >The completed system must be able to record data continuously onto a PC=20 >computer disk, and this >will require the use of an analog-to-digital converter. > >The Dataq Company sells the DI-154RS for $100 (with educational discount)= =20 >an inexpensive, 12- >bit, analog to digital converter that could be used for this system. It=20 >is model number DI-154. It >has terminals for analog input and digital-serial output and is powered by= =20 >the serial port of a PC. >They also sell a 10-bit unit for $25 (DI-194RS). > >The free AmaSeis software for seismic recording is available from Alan=20 >Jones' web site for the DI- >154RS AD unit. > >To use the either Dataq AD unit, one would need to construct a sensor that= =20 >would connect to the >AD via an amplifier and filter circuit. Because of the cost of the AD,=20 >either $125 or $50 would be >available for the sensor/amplifier/filter combination. >____________ > >Another option would be to add an AD with serial output to the=20 >amplifier/filter circuit to allow a >direct connection to the serial port of a PC. That would cut down on the= =20 >cost, but AmaSeis might >need to be modified to accept a new serial format. > >____________ > >Still another option would be to use the PC's game port. The game port is= =20 >designed to sense the >resistance of the joy stick. A field effect transistor (FET) can be used= =20 >to simulate a variable resistor >and the FET "resistance" can be made to vary with the voltage generated by= =20 >the amplifier/filter >circuit. > > >Sincerely, > > >John C. Lahr >Geophysicist >US Geological Survey >National Earthquake Information Center >(303) 273-8596 (tel) >(303) 273-8600 (fax) > > > >Thomas Boyd >Associate Professor >Department of Geophysics >Colorado School of Mines > (303) 273-3522 (tel) >(303) 273-3478 (fax) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismograph From: John & Jan johnjan@........ Date: Thu, 29 Aug 2002 19:04:26 -0600 Hi Ed,

At dataq.com you will find an AD that can translate from analog to serial for your computer's
serial port.  You can record with the Dataq software, or with the $150 12-bit DI154RS unit you
can record with Alan Jones' free AmaSeis program.  I don't know if the $25 10-bit DI194RS unit
will work with AmaSeis, but I plan to test this within a month or two.

You will still need to amplify and filter the output of your Lehman.

For top of the line equipment, AD, and software, check out Larry's site.  It's a bit more
expensive but has many, many added features.
http://www.seismicnet.com/

Good luck with your recording.

John

At 08:26 PM 8/29/2002 -0400, you wrote:
 
 

     I am interested in taking my homemade Lehman Seismograph and feeding it into my computer to look at the data online and to store it for later review. I am looking for a simple system to do this. Can you guide me a little bit? Can I use my sound card as an AD converter? Is there a simple program on the web that well let me see it ONLINE and also STORE it? Thanks a lot. Ed.  

John C. Lahr
1925 Foothills Road
Golden, CO 80402
Phone: (303) 215-9913 
john@........
http://jjlahr.com/science Subject: Re: EPICS Charge to students From: "Larry Cochrane" cochrane@.............. Date: Thu, 29 Aug 2002 20:21:33 -0700 John, I'm not sure what the Colorado School of Mines and Globe program have in mind as far as producing the system is, but I do have a few comments.... I just don't think it's practical or possible for a business to produce a sensor / system for only $150.00. Especially a usable and stable long period device. It would be hard to produce a short period or strong motion sensor for this price. To produce a system like this requires some basic parts, no mater what the actual design looks like. One very important item is a good solid base and this costs money. Just a slab of aluminum can cost $20 to $30. This base will also need to be drilled and taped to hold the sensor parts. This labor costs money. What I'm getting too here is if you do this with each part I think anyone will come up with a total cost somewhere near, or more likely, over $150.00. And that's just for the mechanical parts. The same thing happens with the electronic. By the time you add up the blank PC board cost, electronic parts, box, power supply, build and test labor costs etc etc etc its going to cost somewhere around $100 or more. One way of getting the cost down is to build a lot of units. After all, one can buy a very complicated VCR or DVD player for under $100.00. The difference is they are making a lot (millions?) of units. Selling seismograph systems will always be a small market. No big company is going to invest the millions of dollars need to produce a cheap product if they are only doing to sell a few hindered or even a few thousand, if they are lucky. I would assume that the Colorado School of Mines or Globe program do not want to produce the sensor themselves, so a company would need to do it for them. For a company to make something like this they need to make a profit, unless your Enron . Lets say that one could keep the parts cost down to $150.00 and still produce a good system. A company would need to sell the system for 2 or more times the cost of the raw parts and labor to stay in business. So now the real cost is $300.00 to $500.00 just like my stuff and the AS-1. One other thing. Support. I now spend a few hours each day supporting my equipment. If some company has a lot of these systems in the field with teachers who have never setup a system like this the support cost will go through the roof. This is why a company need to charge may times the raw parts cost to stay in business. Regards, Larry Cochrane Redwood City, PSN ----- Original Message ----- From: "John & Jan" To: Sent: Thursday, August 29, 2002 5:49 PM Subject: Fwd: EPICS Charge to students This semester at the Colorado School of Mines all 350 freshmen will be working on the design of an inexpensive seismic system. They will be divided into 70 groups of 5 for this effort. Because the goal is to design an inexpensive instrument (less than $150) some things may have to be sacrificed, including linearity and single-axis sensitivity. The $150 limit (exclusive of a PC) would make this instrument a candidate for the GLOBE program, an educational program with international scope and many collaborators that is currently focused on weather, atmosphere, and biology issues. I will encourage the students to join mailing lists, such as this one, to get information and advice for their projects. The PSN group collectively has a wealth of experience that they could benefit from. A letter with added details follows. Cheers, John >August 20, 2002 >Robert D. Knecht >Colorado School of Mines > >Dear Dr. Knecht, > >The IRIS Consortium Education and Outreach Committee is pleased that the >EPICS Project for this >year will be the design of an inexpensive sensor for seismic >waves. Computers, which are widely >available in K-16 classrooms, have replaced the paper-drum and pen >recorders of earlier years. >IRIS has sponsored the development of AmaSeis, a free, PC-based program >that monitors the real- >time stream of data from a seismometer so that near and distant >earthquakes can be easily recorded >and viewed graphically. > >The principal remaining barrier to more widespread, school-based >earthquake recording systems is >the availability of an inexpensive, yet sensitive, long-period seismic >sensor that can attach to a PC's >serial port via an analog-to-digital converter. > >The least expensive commercially available system (excluding the PC) costs >about $500, which >precludes purchase by very many teachers or schools. If this cost could >be reduced to $150 or less, >it would be within the range of many more budgets and would also be a good >candidate to become >an instrument recommended for use by the Globe >program. > >Design Goals and Options > >Sensitivity > >For the system to be useful in any location on the Earth, it must be able >to record large earthquakes >at any distance -- teleseisms in the terminology of seismologists. This >requires a good signal to >noise ratio in the period range from 1 to 20 seconds. > >The following table gives a rough idea of the amplitude and velocity of >ground motion that would >be expected from a magnitude 7 earthquake at 90 and 180 degrees distance. > >Magnitude 7 at 90 degrees distance: amplitude velocity >Expected 20s period surface wave amplitude [ 5.61E+01 µm] [ 1.76E+01 µm/s] >Expected 1s period body wave amplitude [ 7.93E-01 µm] [ 4.98E+00 µm/s] > >Magnitude 7 at 180 degrees distance: >Expected 20s period surface wave amplitude [ 1.81E+01 µm] [ 5.68E+00 µm/s] >(No direct P-phase at this distance.) > >Construction Strategy > >One strategy might be to look at commercially available recording systems, >such as the AS1 > on display at CSM, the Sprengnether >, and the designs of >the Public Seismic >Network and >. Explore ways in which the >cost of manufacture, and >hence, the cost of purchase of these instruments could be reduced by >eliminating expensive or >carefully machined components. > >Either a high-school teacher with little or no mechanical and fabrication >skill should be able to >build one from scratch for about $150, or, if you choose to reduce costs >by distributing instruments >in kit form, the cost to the fabricator must be such that an >easily-assembled kit will sell for less than >$150. > >Sensor > >The sensor could be based on the voltage generated by relative motion >between a coil and magnet, >on the proximity of a magnet to a Hall-effect sensor, on the amount of >light reaching a photo diode >that is partially blocked by a flag, on the strain of a piezoelectric >crystal, or on the output of a micro >machined accelerometer similar to those used to trigger the release of an >automobile's air bag. >Given that new, high-density, low-cost disk drives are continually coming >to market, there may >well be some sophisticated, mass-produced, and yet inexpensive components >that could also be >used for this application. > >Recording Options > >The completed system must be able to record data continuously onto a PC >computer disk, and this >will require the use of an analog-to-digital converter. > >The Dataq Company sells the DI-154RS for $100 (with educational discount) >an inexpensive, 12- >bit, analog to digital converter that could be used for this system. It >is model number DI-154. It >has terminals for analog input and digital-serial output and is powered by >the serial port of a PC. >They also sell a 10-bit unit for $25 (DI-194RS). > >The free AmaSeis software for seismic recording is available from Alan >Jones' web site for the DI- >154RS AD unit. > >To use the either Dataq AD unit, one would need to construct a sensor that >would connect to the >AD via an amplifier and filter circuit. Because of the cost of the AD, >either $125 or $50 would be >available for the sensor/amplifier/filter combination. >____________ > >Another option would be to add an AD with serial output to the >amplifier/filter circuit to allow a >direct connection to the serial port of a PC. That would cut down on the >cost, but AmaSeis might >need to be modified to accept a new serial format. > >____________ > >Still another option would be to use the PC's game port. The game port is >designed to sense the >resistance of the joy stick. A field effect transistor (FET) can be used >to simulate a variable resistor >and the FET "resistance" can be made to vary with the voltage generated by >the amplifier/filter >circuit. > > >Sincerely, > > >John C. Lahr >Geophysicist >US Geological Survey >National Earthquake Information Center >(303) 273-8596 (tel) >(303) 273-8600 (fax) > > > >Thomas Boyd >Associate Professor >Department of Geophysics >Colorado School of Mines > (303) 273-3522 (tel) >(303) 273-3478 (fax) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismograph From: "Larry Cochrane" cochrane@.............. Date: Thu, 29 Aug 2002 20:27:11 -0700 Ed, Sound cards are designed for the human ear so most of them do not have = the low frequency response needed to record earthquakes. You need an A/D = board that has a DC path to the A/D chip. Also, stay away from 8 bit A/D = boards. They just don't have the dynamic range need to record = earthquakes. See this page for more info = http://www.seismicnet.com/dynamic.txt. Regards, Larry Cochrane Redwood City, PSN ----- Original Message -----=20 From: Ed Ianni=20 To: psn-l@................. Sent: Thursday, August 29, 2002 5:26 PM Subject: Re: Seismograph I am interested in taking my homemade Lehman Seismograph and = feeding it into my computer to look at the data online and to store it = for later review. I am looking for a simple system to do this. Can you = guide me a little bit? Can I use my sound card as an AD converter? Is = there a simple program on the web that well let me see it ONLINE and = also STORE it? Thanks a lot. Ed. =20

Ed,
 
Sound cards are designed for the human = ear=20 so most of them do not have the low frequency response = needed to=20 record earthquakes. You need an A/D board that has a DC path to the = A/D=20 chip. Also, stay away from 8 bit A/D boards. They just don't have the = dynamic=20 range need to record earthquakes. See this page for more info http://www.seismicnet.com/= dynamic.txt.
 
Regards,
Larry Cochrane
Redwood City, PSN
----- Original Message -----
From:=20 Ed = Ianni=20
Sent: Thursday, August 29, 2002 = 5:26=20 PM
Subject: Re: Seismograph

 
 

     I am = interested in=20 taking my homemade Lehman Seismograph and feeding it into my = computer to=20 look at the data online and to store it for later review. = I am=20 looking for a simple system to do this. Can you guide me a little = bit? Can I=20 use my sound card as an AD converter? Is there a simple program = on the=20 web that well let me see it ONLINE and also STORE it? Thanks a lot.=20 = Ed.   
Subject: Re: EPICS Charge to students From: John & Jan johnjan@........ Date: Thu, 29 Aug 2002 21:44:25 -0600 Hi Larry, Thanks for the feedback. I agree that it may be impossible to meet this target cost: $150 for hardware/Radio Shack parts and labor provided by the teacher or $75 for parts and labor to retail for $150. In any case, it will be interesting to see what the students come up with and in the end they will all learn: that there is a field of study called Seismology, that earthquakes can be recorded all around the globe, that most of what we know about the Earth's interior comes from seismic waves, and that it's not very easy to build an operating seismograph system that can detect teleseisms. If a group does meet this price goal, all the better. Cheers, John At 08:21 PM 8/29/2002 -0700, you wrote: >John, > >I'm not sure what the Colorado School of Mines and Globe program have in >mind as far as producing the system is, but I do have a few comments.... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: EPICS Charge to students From: "Jonathan Peakall" jpeakall@............ Date: Fri, 30 Aug 2002 06:30:51 -0700 John, Yeah! Now that is a project after my own heart! It is exactly what I am trying to do with my station. If I can make a cheap and functional station, I will be able to talk three area schools into one. Having three stations within a 30 mile radius would be very cool indeed! Finding a way to a low cost station is a very worthy goal. I would like to encourage all to put their minds on it. I can readily see all of Larry's points, but is the plan for a company to produce this equipment, or is it to be built by students/teachers? Certainly a for-profit company couldn't stay in business. The greatest objection I see (and remember this is from a someone who only started playing this game a few weeks ago) is the sensitivity goal of being able to detect world-wide earthquakes for $150. In my case, since I live in California, my goal is to detect regional and perhaps very large distance quakes. If the goal is to build a "real" seismic network of schools, it seems unrealistic. If however, if it is to teach and spark interest about earthquakes, very possible. A professional, reliable system has to cost more than $150. The thing is, I don't think it needs to be "up to snuff" to have excellent educational possibilities. I look forward to hearing about progress on this project! Regards, Jonathan Peakall __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: EPICS Charge to students From: ian@........... Date: Fri, 30 Aug 2002 14:32:41 +0100 (BST) looking at the epics spec has me wondering about cheap sensors. I like to think radical and here's one which may well be so but also nice and cheap. The thought is of a cube of concrete, say 100 Kg in mass, sitting on springs at each corner. This sits on a concrete floor with a piezo crystal mounted underneath the centre of the block. The piezo is compressed against the block to bias the sensor by an adjustable platform. Based on the figures quoted by the epics requirement for a 180 degree away mag 7 seism, the inertia of the block should produce a force of about 10 microNewtons (feel free to check this figure!). The hope is that this would produce a measurable voltage change by the crystal. To make this all nice and cheap, you can pour your own concrete block, perhaps consider using car engine valve springs (no idea what period this would give) and a crystal from the likes of a hand-held gas stove lighter. This doesn't get you a system for $150 but it may help to reduce costs. I'd appreciate comments on what sort of signal might be produced from the sensor and the resonant freq. A challenge! I might build one myself too... TIA Ian Smith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: EPICS Charge to students From: CapAAVSO@....... Date: Fri, 30 Aug 2002 10:00:23 EDT In a message dated 8/30/02 4:22:01 AM GMT Daylight Time,=20 cochrane@.............. writes: > I'm not sure what the Colorado School of Mines and Globe program have in > mind as far as producing the system is, but I do have a few comments.... > I just don't think it's practical or possible for a business to produce a > sensor / system for only $150.00.=20 Larry,=20 The Colorado School of Mines is certainly smart enough to realize you can't=20 buy a complete working system for $150. They must have meant for the=20 students, with the help of their teacher, to build their own seismometer=20 which after all is the heart of the system and the biggest part of the cost.= =20 A homemade Lehman seismometer can be built from about $25 worth of parts fro= m=20 Home Depot. David Saum,=20 << DSaum@............ >>, sells a board with A/D converter, amplifier,=20 filter and pick up coil for $99 that works with AmaSeis software which is=20 free and produces a nice drum-format seismogram. I have such a system and I'= m=20 sure that we of the PSN will be glad to help any teacher build and set up a=20 similar system which will then cost less than $150 and meet the Colorado=20 School of Mines cost requirement. Besides, if the students build their own=20 they will learn a heck of a lot more about seismology than they would by jus= t=20 looking at something the school bought for them. Best regards,=20 Cap (Casper Hossfield) Vernon, NJ, USA --------------------------------------------------------------------- Original message: John, I'm not sure what the Colorado School of Mines and Globe program have in mind as far as producing the system is, but I do have a few comments.... I just don't think it's practical or possible for a business to produce a sensor / system for only $150.00. Especially a usable and stable long period device. It would be hard to produce a short period or strong motion sensor for this price. To produce a system like this requires some basic parts, no mater what the actual design looks like. One very important item is a good solid base and this costs money. Just a slab of aluminum can cost $20 to $30. This base will also need to be drilled and taped to hold the sensor parts. This labor costs money. What I'm getting too here is if you do this with each part I think anyone will come up with a total cost somewhere near, or more likely, over $150.00. And that's just for the mechanical parts. The same thing happens with the electronic. By the time you add up the blank PC board cost, electronic parts, box, power supply, build and test labor costs etc etc etc its going to cost somewhere around $100 or more. One way of getting the cost down is to build a lot of units. After all, one can buy a very complicated VCR or DVD player for under $100.00. The difference is they are making a lot (millions?) of units. Selling seismograph systems will always be a small market. No big company is going to invest the millions of dollars need to produce a cheap product if they are only doing to sell a few hindered or even a few thousand, if they are lucky. I would assume that the Colorado School of Mines or Globe program do not want to produce the sensor themselves, so a company would need to do it for them. For a company to make something like this they need to make a profit, unless your Enron . Lets say that one could keep the parts cost down to $150.00 and still produce a good system. A company would need to sell the system for 2 or more times the cost of the raw parts and labor to stay in business. So now the real cost is $300.00 to $500.00 just like my stuff and the AS-1. One other thing. Support. I now spend a few hours each day supporting my equipment. If some company has a lot of these systems in the field with teachers who have never setup a system like this the support cost will go through the roof. This is why a company need to charge may times the raw parts cost to stay in business. Regards, Larry Cochrane Redwood City, PSN ----- Original Message ----- From: "John & Jan" To: Sent: Thursday, August 29, 2002 5:49 PM Subject: Fwd: EPICS Charge to students This semester at the Colorado School of Mines all 350 freshmen will be working on the design of an inexpensive seismic system. They will be divided into 70 groups of 5 for this effort. Because the goal is to design an inexpensive instrument (less than $150) some things may have to be sacrificed, including linearity and single-axis sensitivity. The $150 limit (exclusive of a PC) would make this instrument a candidate for the GLOBE program, an educational program with international scope and many collaborators that is currently focused on weather, atmosphere, and biology issues. I will encourage the students to join mailing lists, such as this one, to get information and advice for their projects. The PSN group collectively has a wealth of experience that they could benefit from. A letter with added details follows. Cheers, John >August 20, 2002 >Robert D. Knecht >Colorado School of Mines > >Dear Dr. Knecht, > >The IRIS Consortium Education and Outreach Committee is pleased that the >EPICS Project for this >year will be the design of an inexpensive sensor for seismic >waves. Computers, which are widely >available in K-16 classrooms, have replaced the paper-drum and pen >recorders of earlier years. >IRIS has sponsored the development of AmaSeis, a free, PC-based program >that monitors the real- >time stream of data from a seismometer so that near and distant >earthquakes can be easily recorded >and viewed graphically. > >The principal remaining barrier to more widespread, school-based >earthquake recording systems is >the availability of an inexpensive, yet sensitive, long-period seismic >sensor that can attach to a PC's >serial port via an analog-to-digital converter. > >The least expensive commercially available system (excluding the PC) costs >about $500, which >precludes purchase by very many teachers or schools. If this cost could >be reduced to $150 or less, >it would be within the range of many more budgets and would also be a good >candidate to become >an instrument recommended for use by the Globe >program. > >Design Goals and Options > >Sensitivity > >For the system to be useful in any location on the Earth, it must be able >to record large earthquakes >at any distance -- teleseisms in the terminology of seismologists. This >requires a good signal to >noise ratio in the period range from 1 to 20 seconds. > >The following table gives a rough idea of the amplitude and velocity of >ground motion that would >be expected from a magnitude 7 earthquake at 90 and 180 degrees distance. > >Magnitude 7 at 90 degrees distance: amplitude velocity >Expected 20s period surface wave amplitude [ 5.61E+01 =B5m] [ 1.76E+01 =B5m/s] >Expected 1s period body wave amplitude [ 7.93E-01 =B5m] [ 4.98E+00 =B5m/s] > >Magnitude 7 at 180 degrees distance: >Expected 20s period surface wave amplitude [ 1.81E+01 =B5m] [ 5.68E+00 =B5m/s] >(No direct P-phase at this distance.) > >Construction Strategy > >One strategy might be to look at commercially available recording systems, >such as the AS1 > on display at CSM, the Sprengnether >, and the designs of >the Public Seismic >Network and >. Explore ways in which the >cost of manufacture, and >hence, the cost of purchase of these instruments could be reduced by >eliminating expensive or >carefully machined components. > >Either a high-school teacher with little or no mechanical and fabrication >skill should be able to >build one from scratch for about $150, or, if you choose to reduce costs >by distributing instruments >in kit form, the cost to the fabricator must be such that an >easily-assembled kit will sell for less than >$150. > >Sensor > >The sensor could be based on the voltage generated by relative motion >between a coil and magnet, >on the proximity of a magnet to a Hall-effect sensor, on the amount of >light reaching a photo diode >that is partially blocked by a flag, on the strain of a piezoelectric >crystal, or on the output of a micro >machined accelerometer similar to those used to trigger the release of an >automobile's air bag. >Given that new, high-density, low-cost disk drives are continually coming >to market, there may >well be some sophisticated, mass-produced, and yet inexpensive components >that could also be >used for this application. > >Recording Options > >The completed system must be able to record data continuously onto a PC >computer disk, and this >will require the use of an analog-to-digital converter. > >The Dataq Company sells the DI-154RS for $100 (with educational discount) >an inexpensive, 12- >bit, analog to digital converter that could be used for this system. It >is model number DI-154. It >has terminals for analog input and digital-serial output and is powered by >the serial port of a PC. >They also sell a 10-bit unit for $25 (DI-194RS). > >The free AmaSeis software for seismic recording is available from Alan >Jones' web site for the DI- >154RS AD unit. > >To use the either Dataq AD unit, one would need to construct a sensor that >would connect to the >AD via an amplifier and filter circuit. Because of the cost of the AD, >either $125 or $50 would be >available for the sensor/amplifier/filter combination. >____________ > >Another option would be to add an AD with serial output to the >amplifier/filter circuit to allow a >direct connection to the serial port of a PC. That would cut down on the >cost, but AmaSeis might >need to be modified to accept a new serial format. > >____________ > >Still another option would be to use the PC's game port. The game port is >designed to sense the >resistance of the joy stick. A field effect transistor (FET) can be used >to simulate a variable resistor >and the FET "resistance" can be made to vary with the voltage generated by >the amplifier/filter >circuit. > > >Sincerely, > > >John C. Lahr >Geophysicist >US Geological Survey >National Earthquake Information Center >(303) 273-8596 (tel) >(303) 273-8600 (fax) > > > >Thomas Boyd >Associate Professor >Department of Geophysics >Colorado School of Mines > (303) 273-3522 (tel) >(303) 273-3478 (fax) In a message dated 8/30/02 4:22:01 AM GMT Daylight Tim= e, cochrane@.............. writes:


I'm not sure what the Colorado=20= School of Mines and Globe program have in
mind as far as producing the system is, but I do have a few comments....
I just don't think it's practical or possible for a business to produce a sensor / system for only $150.00.


Larry,

The Colorado School of Mines is certainly smart enough to realize you can't=20= buy a complete working system for $150. They must have meant for the student= s, with the help of their teacher, to build their own seismometer which afte= r all is the heart of the system and the biggest part of the cost. A homemad= e Lehman seismometer can be built from about $25 worth of parts from Home De= pot. David Saum,
<<  DSaum@............ >>, sells a board with A/D converter= , amplifier, filter and pick up coil for $99 that works with AmaSeis softwar= e which is free and produces a nice drum-format seismogram. I have such a sy= stem and I'm sure that we of the PSN will be glad to help any teacher build=20= and set up a similar system which will then cost less than $150 and meet the= Colorado School of Mines cost requirement. Besides, if the students build t= heir own they will learn a heck of a lot more about seismology than they wou= ld by just looking at something the school bought for them.

Best regards,
Cap
(Casper Hossfield)
Vernon, NJ, USA
---------------------------------------------------------------------
Original message:

John,

I'm not sure what the Colorado School of Mines and Globe program have in
mind as far as producing the system is, but I do have a few comments....

I just don't think it's practical or possible for a business to produce a sensor / system for only $150.00. Especially a usable and stable long period=
device. It would be hard to produce a short period or strong motion sensor for this price.

To produce a system like this requires some basic parts, no mater what the actual design looks like. One very important item is a good solid base and this costs money. Just a slab of aluminum can cost $20 to $30.  This ba= se
will also need to be drilled and taped to hold the sensor parts. This labor<= BR> costs money. What I'm getting too here is if you do this with each part I think anyone will come up with a total cost somewhere near, or more likely,<= BR> over $150.00. And that's just for the mechanical parts.

The same thing happens with the electronic. By the time you add up the blank=
PC board cost, electronic parts, box, power supply, build and test labor
costs etc etc etc its going to cost somewhere around $100 or more. One way of getting the cost down is to build a lot of units. After all, one can buy<= BR> a very complicated VCR or DVD player for under $100.00. The difference is they are making a lot (millions?) of units. Selling seismograph systems will=
always be a small market. No big company is going to invest the millions of<= BR> dollars need to produce a cheap product if they are only doing to sell a few=
hindered or even a few thousand, if they are lucky.

I would assume that the Colorado School of Mines or Globe program do not
want to produce the sensor themselves, so a company would need to do it for<= BR> them. For a company to make something like this they need to make a profit,<= BR> unless your Enron <grin>. Lets say that one could keep the parts cost=20= down
to $150.00 and still produce a good system. A company would need to sell the=
system for 2 or more times the cost of the raw parts and labor to stay in business. So now the real cost is $300.00 to $500.00 just like my stuff and<= BR> the AS-1.

One other thing. Support. I now spend a few hours each day supporting my
equipment. If some company has a lot of these systems in the field with
teachers who have never setup a system like this the support cost will go through the roof. This is why a company need to charge may times the raw
parts cost to stay in business.

Regards,
Larry Cochrane
Redwood City, PSN

----- Original Message -----
From: "John & Jan" <johnjan@........>
To: <psn-l@..............>
Sent: Thursday, August 29, 2002 5:49 PM
Subject: Fwd: EPICS Charge to students


This semester at the Colorado School of Mines all 350 freshmen will be
working on the
design of an inexpensive seismic system.  They will be divided into 70<= BR> groups of 5 for
this effort.  Because the goal is to design an inexpensive instrument (= less
than $150)
some things may have to be sacrificed,  including linearity and single-= axis
sensitivity.
The $150 limit (exclusive of a PC) would make this instrument a candidate for the
GLOBE program, an educational program with international scope and
many collaborators that is currently focused on weather, atmosphere, and
biology
issues.

I will encourage the students to join mailing lists,  such as this one,= to
get information
and advice for their projects.  The PSN group collectively has a wealth= of
experience that
they could benefit from.

A letter with added details follows.

Cheers,
John


>August 20, 2002
>Robert D. Knecht
>Colorado School of Mines
>
>Dear Dr. Knecht,
>
>The IRIS Consortium Education and Outreach Committee is pleased that the=
>EPICS Project for this
>year will be the design of an inexpensive sensor for seismic
>waves.  Computers, which are widely
>available in K-16 classrooms, have replaced the paper-drum and pen
>recorders of earlier years.
>IRIS has sponsored the development of AmaSeis, a free, PC-based program<= BR> >that monitors the real-
>time stream of data from a seismometer so that near and distant
>earthquakes can be easily recorded
>and viewed graphically.
>
>The principal remaining barrier to more widespread, school-based
>earthquake recording systems is
>the availability of an inexpensive, yet sensitive, long-period seismic >sensor that can attach to a PC's
>serial port via an analog-to-digital converter.
>
>The least expensive commercially available system (excluding the PC) cos= ts
>about $500, which
>precludes purchase by very many teachers or schools.  If this cost=20= could
>be reduced to $150 or less,
>it would be within the range of many more budgets and would also be a go= od
>candidate to become
>an instrument recommended for use by the Globe
>program.  <http://www.globe.gov/>
>
>Design Goals and Options
>
>Sensitivity
>
>For the system to be useful in any location on the Earth, it must be abl= e
>to record large earthquakes
>at any distance -- teleseisms in the terminology of seismologists. = This
>requires a good signal to
>noise ratio in the period range from 1 to 20 seconds.
>
>The following table gives a rough idea of the amplitude and velocity of<= BR> >ground motion that would
>be expected from a magnitude 7 earthquake at 90 and 180 degrees distance= ..
>
>Magnitude 7 at 90 degrees distance:      &= nbsp;    amplitude       =20= velocity
>Expected 20s period surface wave amplitude [  5.61E+01 =B5m] =20= [  1.76E+01
=B5m/s]
>Expected 1s period body wave amplitude     [  7= ..93E-01 =B5m]  [  4.98E+00
=B5m/s]
>
>Magnitude 7 at 180 degrees distance:
>Expected 20s period surface wave amplitude [  1.81E+01 =B5m] =20= [  5.68E+00
=B5m/s]
>(No direct P-phase at this distance.)
>
>Construction Strategy
>
>One strategy might be to look at commercially available recording system= s,
>such as the AS1
><http://jjlahr.com/science/psn/as1/> on display at CSM, the Spreng= nether
><http://www.geocities.com/meredithlamb/page026.html>, and the desi= gns of
>the Public Seismic
>Network <http://www.geocities.com/meredithlamb/> and
><http://jjlahr.com/science/psn/gldn_psn.html>. Explore ways in whi= ch the
>cost of manufacture, and
>hence, the cost of purchase of these instruments could be reduced by
>eliminating expensive or
>carefully machined components.
>
>Either a high-school teacher with little or no mechanical and fabricatio= n
>skill should be able to
>build one from scratch for about $150, or, if you choose to reduce costs=
>by distributing instruments
>in kit form, the cost to the fabricator must be such that an
>easily-assembled kit will sell for less than
>$150.
>
>Sensor
>
>The sensor could be based on the voltage generated by relative motion >between a coil and magnet,
>on the proximity of a magnet to a Hall-effect sensor, on the amount of >light reaching a photo diode
>that is partially blocked by a flag, on the strain of a piezoelectric >crystal, or on the output of a micro
>machined accelerometer similar to those used to trigger the release of a= n
>automobile's air bag.
>Given that new, high-density, low-cost disk drives are continually comin= g
>to market, there may
>well be some sophisticated, mass-produced, and yet inexpensive component= s
>that could also be
>used for this application.
>
>Recording Options
>
>The completed system must be able to record data continuously onto a PC<= BR> >computer disk, and this
>will require the use of an analog-to-digital converter.
>
>The Dataq Company sells the DI-154RS for $100 (with educational discount= )
>an inexpensive, 12-
>bit, analog to digital converter that could be used for this system.&nbs= p; It
>is model number DI-154.  It
>has terminals for analog input and digital-serial output and is powered=20= by
>the serial port of a PC.
>They also sell a 10-bit unit for $25 (DI-194RS).   <http://= www.dataq.com/>
>
>The free AmaSeis software for seismic recording is available from Alan >Jones' web site for the DI-
>154RS AD unit.   <http://www.geol.binghamton.edu/faculty/jo= nes/as1.html>
>
>To use the either Dataq AD unit, one would need to construct a sensor th= at
>would connect to the
>AD via an amplifier and filter circuit.  Because of the cost of the= AD,
>either $125 or  $50 would be
>available for the sensor/amplifier/filter combination.
>____________
>
>Another option would be to add an AD with serial output to the
>amplifier/filter circuit to allow  a
>direct connection to the serial port of a PC.  That would cut down=20= on the
>cost, but AmaSeis might
>need to be modified to accept a new serial format.
>
>____________
>
>Still another option would be to use the PC's game port.  The game=20= port is
>designed to sense the
>resistance of the joy stick.  A field effect transistor (FET) can b= e used
>to simulate a variable resistor
>and the FET "resistance" can be made to vary with the voltage generated=20= by
>the amplifier/filter
>circuit.
>
>
>Sincerely,
>
>
>John C. Lahr
>Geophysicist
>US Geological Survey
>National Earthquake Information Center
>(303) 273-8596 (tel)
>(303) 273-8600 (fax)
>
>
>
>Thomas Boyd
>Associate Professor
>Department of Geophysics
>Colorado School of Mines
>  (303) 273-3522 (tel)
>(303) 273-3478 (fax)

Subject: EPICS Links Page From: John & Jan johnjan@........ Date: Fri, 30 Aug 2002 09:22:29 -0600 This is the EPICS links page. Suggestions welcome. http://jjlahr.com/science/psn/epics/links.html I can already think of many that are missing. Of course, just using google.com might be even more helpful. Cheers, John John C. Lahr 1925 Foothills Road Golden, CO 80402 Phone: (303) 215-9913 john@........ http://jjlahr.com/science __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: EPICS Charge to students From: "George Harris" gjharris@............. Date: Fri, 30 Aug 2002 17:30:56 -0700 A comment from George Harris: I am very convinced that a kit could be made to sell for less than $150, but it depends on the volume. My guess is that it would require a market size of more than 1000. If this is a realistic number, and I would think it is, an organized project of the PSN should make it easy. There are many possibilites, but based on my thinking over the past few years with a similar objective in mind, the following are ideas: The sensor is a simple vertical upright pendulum with one or two axes, optical sensing, and magnetic coil feedback. I believe I could make such a unit to sell for $75 or less in kit form including the components for the feedback circuit. Use an 8 bit A/D plus an amplifier with gain of 128 to provide at least 12 bits of output by combining the two words in a pic class microprocessor. This type of processor can also provide a serial interface with proper programming. The component cost should be in the $40 range and can be on the same board that has the optical sensors. I would be glad to cooperate with anyone else to try the design. My major capability is in the mechanics and low cost design of the sensor. George Harris __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: EPICS Links Page From: Raul Alvarez ralvarez@........ Date: Fri, 30 Aug 2002 21:27:23 -0600 Hi John, Thanks for the links list! One link - http://www.keckes.com/seismo - , seems to be bad. Can you check and see if perhaps it was typed incorrectly? Raul John & Jan wrote: > This is the EPICS links page. Suggestions welcome. > http://jjlahr.com/science/psn/epics/links.html > I can already think of many that are missing. > > Of course, just using google.com might be even more helpful. > > Cheers, > John > > John C. Lahr > 1925 Foothills Road > Golden, CO 80402 > Phone: (303) 215-9913 > john@........ > http://jjlahr.com/science > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: EPICS Charge to students From: "Mauro Mariotti" mariotti@......... Date: Sat, 31 Aug 2002 10:42:11 +0200 Hi all, I have activated a forum at my web site. www.infoeq.it/forum On the wave of the Globe program I have activated also a forum topic about it. The forum could contain messages in italian but you can freely post messages in english. If you feel to advise the addition of more topics write me about i'll be happy to add specific topics. regards Mauro __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: EPICS Links Page From: ChrisAtUpw@....... Date: Sun, 1 Sep 2002 18:14:12 EDT Hi John, I suggest that you have someone at the Colorado School of Mines=20 Project download all the PSN letters and put them into annual files. They ca= n=20 then be searched with 'Find' from the WP programme using keywords. Following Larry's letter, I checked on a base for seismometers. I=20 found that I could buy an 18" hexagonal concrete slab, some 1/2" square stee= l=20 bar and three socket cap screws for less than $10. Other suggestions include= d=20 stone / granite slabs which had defects preventing them from being saleable,= =20 armoured glass from when banks updated their security systems, metal disks e= x=20 industrial processes, offcuts from metal suppliers, various offerings from=20 scrap metal merchants, polyester fibreglass + sand mouldings, melamine=20 covered high density chipboard offcuts from kitchen worktops and laminated,=20 varnished hardwood. My own favourite is a 'puddle it yourself' cement and=20 sand mix, so that you can mould in all the necessary holes for the support=20 and mounting bolts.=20 I also looked at circuit board options. Pin board and punched=20 stripboard are not expensive and neither are the components. If you are daft= =20 enough to specify DIP board for general purpose printed circuits, you do get= =20 into the idiot price bracket.=20 > Sensitivity > For the system to be useful in any location on the Earth, it must be able=20 > to record large earthquakes at any distance -- (teleseisms). This require= s=20 > a good signal to noise ratio in the period range from 1 to 20 seconds. > The following table gives a rough idea of the amplitude and velocity of=20 > ground motion that would be expected from a magnitude 7 earthquake at 90=20 > and 180 degrees distance. >=20 > Magnitude 7 at 90 degrees distance: amplitude velocity > Expected 20s period surface wave amplitude [ 5.61E+01 =B5m] [ 1.76E+01 > =B5m/s] > Expected 1s period body wave amplitude [ 7.93E-01 =B5m] [ 4.98E+00 > =B5m/s] >=20 > Magnitude 7 at 180 degrees distance: > Expected 20s period surface wave amplitude [ 1.81E+01 =B5m] [ 5.68E+00 > =B5m/s] >=20 This should not be difficult. > Sensor >=20 > The sensor could be based on the voltage generated by relative motion >=20 OK. >=20 OK. on the amount of=20 >=20 OK. >=20 OK for down to 0.1 Hz, but the longer times may be a problem.=20 > machined accelerometer similar to those used to=20 >=20 These are very noisy. Two more systems both based on the NE5521N chip, which can obtain nm=20 resolution. LVDT sensors. These can be made for ranges up to +/- 10 mm LCDT sensors. Better for ranges <+/-1 mm and FFB seismometers > Given that new, high-density, low-cost disk drives are continually coming > to market, there may well be some sophisticated, mass-produced, and yet=20 > inexpensive components that could also be used for this application. I have not seen the 100 MB zip drives mentioned? Regards, Chris Chapman=20 Hi John,

      I suggest that you have someone at=20= the Colorado School of Mines Project download all the PSN letters and put th= em into annual files. They can then be searched with 'Find' from the WP prog= ramme using keywords.

      Following Larry's letter, I checked= on a base for seismometers. I found that I could buy an 18" hexagonal concr= ete slab, some 1/2" square steel bar and three socket cap screws for less th= an $10. Other suggestions included stone / granite slabs which had defects p= reventing them from being saleable, armoured glass from when banks updated t= heir security systems, metal disks ex industrial processes, offcuts from met= al suppliers, various offerings from scrap metal merchants, polyester fibreg= lass + sand mouldings, melamine covered high density chipboard offcuts from=20= kitchen worktops and laminated, varnished hardwood. My own favourite is a 'p= uddle it yourself' cement and sand mix, so that you can mould in all the nec= essary holes for the support and mounting bolts.=20

      I also looked at circuit board opti= ons. Pin board and punched stripboard are not expensive and neither are the=20= components. If you are daft enough to specify DIP board for general purpose=20= printed circuits, you do get into the idiot price bracket.=20


Sensitivity
For the system to be useful in any location on the Earth, it must be abl= e to record large earthquakes at any distance -- (teleseisms).  This re= quires a good signal to noise ratio in the period range from 1 to 20 seconds= .
The following table gives a rough idea of the amplitude and velocity of=20= ground motion that would be expected from a magnitude 7 earthquake at 90 and= 180 degrees distance.

Magnitude 7 at 90 degrees distance:       =     amplitude        = velocity
Expected 20s period surface wave amplitude [  5.61E+01 =B5m]  = [  1.76E+01
=B5m/s]
Expected 1s period body wave amplitude     [  7= ..93E-01 =B5m]  [  4.98E+00
=B5m/s]

Magnitude 7 at 180 degrees distance:
Expected 20s period surface wave amplitude [  1.81E+01 =B5m]  = [  5.68E+00
=B5m/s]
(No direct P-phase at this distance.)


      This should not be difficult.

Sensor

The sensor could be based on the voltage generated by relative motion
between a coil and magnet,


      OK.

on the proximity of a magne= t to a Hall-effect sensor,


      OK.

on the amount of=20
light reaching a photo diod= e that is partially blocked by a flag,


      OK.

on the strain of a piezoelectric
crystal,


      OK for down to 0.1 Hz, but the long= er times may be a problem.=20

on the output of a micro
ma= chined accelerometer similar to those used to trigger the release of an auto= mobile's air bag.


      These are very noisy.

      Two more systems both based on the=20= NE5521N chip, which can obtain nm resolution.

      LVDT sensors. These can be made for= ranges up to +/- 10 mm
      LCDT sensors. Better for ranges <= ;+/-1 mm and FFB seismometers

Given that new, high-densit= y, low-cost disk drives are continually coming
to market, there may well be some sophisticated, mass-produced, and yet=20= inexpensive components that could also be used for this application.
<= FONT COLOR=3D"#000000" SIZE=3D3 FAMILY=3D"SANSSERIF" FACE=3D"Arial" LANG= =3D"0">


      I have not seen the 100 MB zip driv= es mentioned?

      Regards,

      Chris Chapman=20
Subject: Re: EPICS Charge to students From: ChrisAtUpw@....... Date: Sun, 1 Sep 2002 18:22:37 EDT In a message dated 31/08/02, gjharris@............. writes: > I am very convinced that a kit could be made to sell for less than $150, but > it depends on the volume. My guess is that it would require a market size > If you use a 'cottage industry' rather than the 'big corporation' approch you should get it lower. There are many possibilites, but based on my thinking over the past > few years with a similar objective in mind, the following are ideas: The > sensor is a simple vertical upright pendulum with one or two axes, optical > sensing, and magnetic coil feedback. I believe I could make such a unit to > sell for $75 or less in kit form including the components for the feedback > It would be a great opportunity to use the four pole ex hard drive magnets and thin flat coils to make and integrating SG seis. Sensing could be either linear optical or linear magnetic displacement. I u > se an 8 bit A/D plus an amplifier with gain of 128 to provide at least 12 > bits of output by combining the two words in a pic class > microprocessor.This type of processor can also provide a serial interface > with proper programming. The component cost should be in the $40 range and > can be on the same board that has the optical sensors. > > I would be glad to cooperate with anyone else to try the design. My major > capability is in the mechanics and low cost design of the sensor. The 10-bit Dataq unit for $25, DI-194RS, looks like a good starting point, with a four channel 240 sps capability. Regards, Chris Chapman In a message dated 31/08/02, gjharris@............. writes:

I am very convinced that a kit could be made to sell for less than $150, but it depends on the volume.  My guess is that it would require a market size of more than 1000.


      If you use a 'cottage industry' rather than the 'big corporation' approch you should get it lower.  

There are many possibilites, but based on my thinking over the past
few years with a similar objective in mind, the following are ideas: The sensor is a simple vertical upright pendulum with one or two axes, optical sensing, and magnetic coil feedback.  I believe I could make such a unit to sell for $75 or less in kit form including the components for the feedback circuit.


      It would be a great opportunity to use the four pole ex hard drive magnets and thin flat coils to make and integrating SG seis. Sensing could be either linear optical or linear magnetic displacement.

I u
se an 8 bit A/D plus an amplifier with gain of 128 to provide at least 12 bits of output by combining the two words in a pic class microprocessor.This type of processor can also provide a serial interface with proper programming.  The component cost should be in the $40 range and can be on the same board that has the optical sensors.

I would be glad to cooperate with anyone else to try the design.  My major capability is in the mechanics and low cost design of the sensor.


      The 10-bit Dataq unit for $25, DI-194RS, looks like a good starting point, with a four channel 240 sps capability.    

      Regards,

      Chris Chapman
Subject: Seismic "Hookup" From: Ed Ianni eianni2@........... Date: Sun, 01 Sep 2002 23:35:31 -0400 Hi All; I am very new to seismology and I thank you all for your previous help. Initially I would like to get into seismology in an inexpensive way. Am I right in assuming that I can connect the DATAQ STARTER KIT input to the output ( 2 wires) of my pre-amplifier (which is fed by a lehman sensor [together they are currently driving a Perkin-Elmer chart recorder ])....and then take the output of the DATAQ STARTER KIT and feed it into the serial port of my computer? Thank you very much. Ed.
Hi All;
        I am very new to seismology and I thank you all for your previous help. Initially I would like to get into seismology in an inexpensive  way. Am I right in assuming that I can connect the DATAQ STARTER KIT input to the output ( 2 wires) of my pre-amplifier (which is fed by a  lehman sensor [together they are currently driving a Perkin-Elmer chart recorder ])....and then take the output of the DATAQ STARTER KIT and feed it into the serial port of my computer?
                                                                                                     Thank you very much.    Ed.   
Subject: networking From: "Barry" gbl@....... Date: Sun, 1 Sep 2002 21:41:54 -0700 Hi All I purchased an PCanywhere ver 9.2 recently. It includes a DOS version = (5.0- I think) . I hope to remote monitor SDR from a windows computer on = my network. I was able to get a computer running win98 to hook-up with = DOS pcanywhere running on a "restart in DOS mode" win95 computer. = Since I only have one of Larrys boards running, I decided to run EMON on = the DOS computer with an EMON compatible board. I can start the program = but I get vertically two displays on the windows monitor but the DOS = monitor is fine. Also the font in the windows 95 screen is red ???? = Has anybody run pcanywhere with a windows computer remote controling a = DOS machine? . BTW I have to "net logon" in the DOS window before = starting DOS pcanywhere. I'm not sure this is normal. Regards Barry
Hi All
  I purchased an PCanywhere ver = 9.2 recently.=20 It includes a DOS version (5.0- I think) . I hope to remote monitor SDR = from a=20 windows computer on my network. I was able to get a  computer = running win98=20 to hook-up with DOS pcanywhere running on a "restart in DOS mode"  = win95=20 computer.  Since I only have one of Larrys boards running, I = decided to run=20 EMON on the DOS computer with an EMON compatible board. I can start = the=20 program but I get vertically two displays on the windows monitor but the = DOS=20 monitor is fine. Also the font in the windows 95 screen is red = ????  =20 Has anybody run  pcanywhere with  a windows computer remote = controling=20 a DOS machine? . BTW  I have to "net logon" in the DOS window = before=20 starting DOS pcanywhere. I'm not sure this is normal.
Regards
Barry
Subject: Re: Seismic "Hookup" From: "Mauro Mariotti" mariotti@......... Date: Mon, 2 Sep 2002 08:24:53 +0200 Hi Ed, yes, the idea is ok. for the all members of the list: does someone knows the communication protocol of the Dataq converter? Or there is a web site where it is described. I'll make a little = internet research... but if someone knows something please post the info... thanks Mauro ----- Original Message -----=20 From: Ed Ianni=20 To: psn-l@................. Sent: Monday, September 02, 2002 5:35 AM Subject: Seismic "Hookup" Hi All; I am very new to seismology and I thank you all for your = previous help. Initially I would like to get into seismology in an = inexpensive way. Am I right in assuming that I can connect the DATAQ = STARTER KIT input to the output ( 2 wires) of my pre-amplifier (which is = fed by a lehman sensor [together they are currently driving a = Perkin-Elmer chart recorder ])....and then take the output of the DATAQ = STARTER KIT and feed it into the serial port of my computer?=20 = Thank you very much. Ed. =20
Hi Ed,
yes, the idea is ok.
 
for the all members of the = list:
does someone knows the communication = protocol of=20 the Dataq converter?
Or there is a web site where it is = described. I'll=20 make a little internet research...
but if someone knows something please = post the=20 info...
thanks
Mauro
 
----- Original Message -----
From:=20 Ed = Ianni=20
Sent: Monday, September 02, = 2002 5:35=20 AM
Subject: Seismic "Hookup"

Hi All;
        I am=20 very new to seismology and I thank you all for your previous help. = Initially I=20 would like to get into seismology in an inexpensive  way. Am I right in assuming that I can connect the = DATAQ STARTER=20 KIT input to the output ( 2 wires) of my = pre-amplifier (which=20 is fed by a  lehman sensor [together they=20 are currently driving a Perkin-Elmer chart recorder = ])....and=20 then take the output of the DATAQ STARTER=20 KIT and feed it into the serial port of my computer?
          &nbs= p;            = ;            =             &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p;            = ;    =20 Thank you very much.   =20 Ed.   
Subject: Oregon Event From: "Bob Hancock" robert.hancock@........... Date: Mon, 2 Sep 2002 12:21:26 -0400 The USGS just published an event with the following parameters: Date-Time 2002 09 02 15:17:13 UTC Location 44.01N 127.92W Depth 10.0 kilometers Magnitude 4.4 Region OFF COAST OF OREGON Reference 190 miles (305 km) WNW of Coos Bay, Oregon However, I believe that it was closer to 1339 for the actual event. You can check the times on the Pacific Northwest helicorders, and also it was visible on Larry's LC3 channel. I recorded the event in New Jersey with the peak L & R waves about 1403. A check of the local helicorders in the Pacific Northwest and also the Lamont-Daugherty helicorder, just north of New York City, shows no event that matches their published specification. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Oregon Event From: Hammonds hammond@........... Date: Mon, 02 Sep 2002 08:57:21 -0800 It looks like the event shows up at COR (corvallis, oregon) at about 1339: http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/COR_24hr.html However, there is another arrival at about 1519 on COR which could be a phase arrival of this event. Perhaps the analyst got them mixed up? Bob Alaska Public Seismic Network http://apsn.awcable.com At 08:21 AM 9/2/2002, you wrote: >The USGS just published an event with the following parameters: > >Date-Time 2002 09 02 15:17:13 UTC >Location 44.01N 127.92W >Depth 10.0 kilometers >Magnitude 4.4 >Region OFF COAST OF OREGON >Reference 190 miles (305 km) WNW of Coos Bay, Oregon > >However, I believe that it was closer to 1339 for the actual event. You can >check the times on the Pacific Northwest helicorders, and also it was >visible on Larry's LC3 channel. I recorded the event in New Jersey with the >peak L & R waves about 1403. > >A check of the local helicorders in the Pacific Northwest and also the >Lamont-Daugherty helicorder, just north of New York City, shows no event >that matches their published specification. > >Bob > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: aslwww ?? From: David A Nelson davenn@............... Date: Wed, 04 Sep 2002 21:42:58 +1000 speaking of aslwww it seems to have gone offline have not been able to access it for the last 3 days 02 - 04 sept inclusive Problem Report There was a communication problem. Message ID TCP_ERROR Problem Description The system was unable to communicate with the server. Possible Problem Cause The Web server may be down. The Web server may be too busy. The Web server may be experiencing other problems, preventing it from responding to clients. The communication path may be experiencing problems. Possible Solution Try connecting to this server later. hopefully it will be sorted out soon Dave __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: aslwww ?? From: Hammonds hammond@........... Date: Wed, 04 Sep 2002 04:11:31 -0800 Dave, it's down for me too. Bob apsn.awcable.com At 03:42 AM 9/4/2002, you wrote: >speaking of aslwww it seems to have gone offline > > have not been able to access it for the last 3 days > 02 - 04 sept inclusive > > Problem Report > There was a communication problem. > Message ID TCP_ERROR > Problem Description The system was unable to communicate with the server. > Possible Problem Cause > The Web server may be down. > The Web server may be too busy. > The Web server may be experiencing other >problems, preventing it from responding to clients. > The communication path may be experiencing problems. > Possible Solution Try connecting to this server later. > >hopefully it will be sorted out soon > >Dave > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: aslwww ?? From: Hammonds hammond@........... Date: Wed, 04 Sep 2002 16:24:20 -0800 Forwarded email from Bob Hutt, SIC, ASL: 09/04/02 Subject: Re: Access to ASL web page? 09:39 AM Bob Hammond, Sorry, our "webicorder" (nice word!) plots are inaccessible to the outside world right now due to a massive server upgrade we are doing. We should be back on line within a day or two - certainly before the end of the week. Thanks for your patience! Regards, Bob Hutt ===================================== Dr. Charles R. (Bob) Hutt, Scientist-in-Charge ALBUQUERQUE SEISMOLOGICAL LABORATORY US GEOLOGICAL SURVEY 801 UNIVERSITY SE, SUITE 300 ALBUQUERQUE, NM 87106-4345 Telephone: (505)-462-3200 (main office no.) Telephone: (505)-462-3201 (direct line) FAX: (505)-462-3299 Email: hutt@............... Web: http://aslwww.cr.usgs.gov Live Seismograms: http://www.liss.org/ ===================================== At 03:42 AM 9/4/2002, you wrote: >speaking of aslwww it seems to have gone offline > > have not been able to access it for the last 3 days > 02 - 04 sept inclusive > > Problem Report > There was a communication problem. > Message ID TCP_ERROR > Problem Description The system was unable to communicate with the server. > Possible Problem Cause > The Web server may be down. > The Web server may be too busy. > The Web server may be experiencing other >problems, preventing it from responding to clients. > The communication path may be experiencing problems. > Possible Solution Try connecting to this server later. > >hopefully it will be sorted out soon > >Dave > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Big Event From: "Bob Hancock" robert.hancock@........... Date: Thu, 5 Sep 2002 22:08:08 -0400 Something big being recorded on the east coast - P wave arrival 0132:30 UTC, S wave arrival 0141:15 - Both waves very significant - L & R waves still coming in.... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Event From: Charlie Plyler cplyler@.......... Date: Thu, 05 Sep 2002 22:58:52 -0400 As a side note Bob, Recorded electromagnetic anomaly at the same times. Non seismic, but through the earth. Charlie Plyler Elfrad Bob Hancock wrote: > > Something big being recorded on the east coast - P wave arrival 0132:30 UTC, > S wave arrival 0141:15 - Both waves very significant - L & R waves still > coming in.... > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Big Event From: Hammonds hammond@........... Date: Thu, 05 Sep 2002 19:15:25 -0800 .....from the Alaska Tsunami Warning Center: EARTHQUAKE DATA: PRELIMINARY MAGNITUDE: 4.8 LOCATION: 58.0N 151.3W - 55 MILES NE OF KODIAK CITY, AK. 225 MILES SW OF ANCHORAGE, AK. 25 MILES DEEP TIME: 1729 ADT 09/05/2002 1829 PDT 09/05/2002 0129 UTC 09/06/2002 I have an event at 0128 located 767km away, ML 4.4, which fits their solution. Charlie, can you send us a jpg or such of your EM record? Bob Hammond Alaska Public Seismic Network http://apsn.awcable.com At 06:08 PM 9/5/2002, you wrote: >Something big being recorded on the east coast - P wave arrival 0132:30 UTC, >S wave arrival 0141:15 - Both waves very significant - L & R waves still >coming in.... > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Big Event From: "Bob Hancock" robert.hancock@........... Date: Thu, 5 Sep 2002 23:20:05 -0400 Bob - NEIC just came out with a 6.1 event on the north coast of Sicily - Here in Randolph, NJ, I don't think I would receive a M 4.8 Alaskan event as strong as this one was. I have posted my files under the event files. Bob Hancock -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Hammonds Sent: Thursday, September 05, 2002 23:15 To: psn-l@.............. Subject: Re: Big Event .....from the Alaska Tsunami Warning Center: EARTHQUAKE DATA: PRELIMINARY MAGNITUDE: 4.8 LOCATION: 58.0N 151.3W - 55 MILES NE OF KODIAK CITY, AK. 225 MILES SW OF ANCHORAGE, AK. 25 MILES DEEP TIME: 1729 ADT 09/05/2002 1829 PDT 09/05/2002 0129 UTC 09/06/2002 I have an event at 0128 located 767km away, ML 4.4, which fits their solution. Charlie, can you send us a jpg or such of your EM record? Bob Hammond Alaska Public Seismic Network http://apsn.awcable.com At 06:08 PM 9/5/2002, you wrote: >Something big being recorded on the east coast - P wave arrival 0132:30 UTC, >S wave arrival 0141:15 - Both waves very significant - L & R waves still >coming in.... > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismic "Hookup" From: Bobhelenmcclure@....... Date: Fri, 6 Sep 2002 00:45:10 EDT Hi Ed, I use the DI-194RS and the DI-154RS for seismic recording. The DI-154 is preferable over the DI-194 because it has 12-bit A/D conversion, but at the same time, it costs $150 compared to the $25 paid for the RS-194. It will work with your setup, I believe, but your preamp should have a full scale range of +/- 10 volts in order to get all of the dynamic range available from the Dataq starter kit. The Dataq unit samples at a fixed rate of 240 samples per second, but records at any desired rate that is an integer divide of 240. All of the acquired data is input signal averaged, which improves resolution, increases signal-to-noise ratio, attenuates aliasing, and totally rejects 60 Hz and 120 Hz hum. For example, I usually record at 5 samples per second. During the 0.2 second sample interval, 48 data samples taken at the 240 samples per second rate are averaged to yield the recorded sample. The data is resolved to 14 bits. The lower 2 bits of the data word are reserved for marker bits, such as time marks. I equipped a WWVB wall clock with an optical pickoff to mark my recordings at a once-per-minute rate. I developed a drum plot program for display and filtering of recorded data. This program can run simultaneously with the Dataq recorder and display data from the file as it is being recorded. It can output filtered versions of the original file. I find the "Broadband" filter to be most useful, since it extends the usual response of my 3.4 second seismometer out to periods of 20 seconds or more. It is available for downloading from the Dataq web site. It is also on the installation disc for the Dataq Lite Software, in the catalog section. Regards, Bob McClure Hi Ed,

  I use the DI-194RS and the DI-154RS for seismic recording.  The DI-154 is preferable over the DI-194 because it has 12-bit A/D conversion, but at the same time, it costs $150 compared to the $25 paid for the RS-194.  It will work with your setup, I believe, but your preamp should have a full scale range of +/- 10 volts in order to get all of the dynamic range available from the Dataq starter kit.

  The Dataq unit samples at a fixed rate of 240 samples per second, but records at any desired rate that is an integer divide of 240.  All of the acquired data is input signal averaged, which improves resolution, increases signal-to-noise ratio, attenuates aliasing, and totally rejects 60 Hz and 120 Hz hum.  For example, I usually record at 5 samples per second.  During the 0.2 second sample interval, 48 data samples taken at the 240 samples per second rate are averaged to yield the recorded sample.

  The data is resolved to 14 bits.  The lower 2 bits of the data word are reserved for marker bits, such as time marks.  I equipped a WWVB wall clock with an optical pickoff to mark my recordings at a once-per-minute rate.

  I developed a drum plot program for display and filtering of recorded data.  This program can run simultaneously with the Dataq recorder and display data from the file as it is being recorded.  It can output filtered versions of the original file.  I find the "Broadband" filter to be most useful, since it extends the usual response of my 3.4 second seismometer out to periods of 20 seconds or more.  It is available for downloading from the Dataq web site.  It is also on the installation disc for the Dataq Lite Software, in the catalog section.

Regards,

Bob McClure
Subject: RE: Big Event From: Hammonds hammond@........... Date: Thu, 05 Sep 2002 20:52:29 -0800 Bob, you're absolutely right. I blew that one big time. Charlie, interesting record! Thanks for the info. Bob At 07:20 PM 9/5/2002, you wrote: >Bob - > >NEIC just came out with a 6.1 event on the north coast of Sicily - Here in >Randolph, NJ, I don't think I would receive a M 4.8 Alaskan event as strong >as this one was. I have posted my files under the event files. > >Bob Hancock > >-----Original Message----- >From: psn-l-request@.............. [mailto:psn-l-request@................. >Behalf Of Hammonds >Sent: Thursday, September 05, 2002 23:15 >To: psn-l@.............. >Subject: Re: Big Event > >....from the Alaska Tsunami Warning Center: > >EARTHQUAKE DATA: > PRELIMINARY MAGNITUDE: 4.8 > LOCATION: 58.0N 151.3W - 55 MILES NE OF KODIAK CITY, AK. > 225 MILES SW OF ANCHORAGE, AK. > 25 MILES DEEP > TIME: 1729 ADT 09/05/2002 > 1829 PDT 09/05/2002 > 0129 UTC 09/06/2002 > >I have an event at 0128 located 767km away, ML 4.4, which fits their >solution. > >Charlie, can you send us a jpg or such of your EM record? > >Bob Hammond >Alaska Public Seismic Network >http://apsn.awcable.com > > >At 06:08 PM 9/5/2002, you wrote: > >Something big being recorded on the east coast - P wave arrival 0132:30 >UTC, > >S wave arrival 0141:15 - Both waves very significant - L & R waves still > >coming in.... > > > >__________________________________________________________ > > > >Public Seismic Network Mailing List (PSN-L) > > > >To leave this list email PSN-L-REQUEST@.............. with > >the body of the message (first line only): unsubscribe > >See http://www.seismicnet.com/maillist.html for more information. > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: SICILY EARTHQUAKE From: "Francesco" fra.nuc@........... Date: Fri, 6 Sep 2002 14:15:35 +0200 Hi to all. at 1.21 utc a large quake occured in Southern Thyrrenian Sea, 40km north of Sicily. It's very felt all around northern coast of Sicily, in particoular in Palermo, where registered some material damnages and 3 victims due the panic. The quake is a classic subduction event in the area of Eolie-Ustica islands at 25 km of deepth with ~Ms 6.0 I've posted in the ML all the file of our network. Until now we have registered more than 20 agtershock, but with low magnitude (max 4.5). I've interesting about your records. More information on our web site http://www.iesn.org Regards Francesco Nucera - Italy __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Big Event From: "Bob Hancock" robert.hancock@........... Date: Fri, 6 Sep 2002 09:06:01 -0400 Charlie - Have you correlated your electromagnetic activity with the P wave and phase arrival times from the Sicily event. If so, could you send me a copy of the data. Just curious. I have read about electromagnetic activity coming from compression of the rocks during an earthquake. I am curious how your data correlates to the event. Bob Hancock -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Charlie Plyler Sent: Thursday, September 05, 2002 22:59 To: psn-l@.............. Subject: Re: Big Event As a side note Bob, Recorded electromagnetic anomaly at the same times. Non seismic, but through the earth. Charlie Plyler Elfrad Bob Hancock wrote: > > Something big being recorded on the east coast - P wave arrival 0132:30 UTC, > S wave arrival 0141:15 - Both waves very significant - L & R waves still > coming in.... > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: rockland filter on ebay From: BOB BARNS royb1@........... Date: Sat, 07 Sep 2002 20:43:45 -0400 Hi gang, Item # 1765093197 on ebay is a dual filter which may be of interest. Ends Sep-14-02 19:37:26 PDT Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Big,,,, BIG,,,, VERY BIG From: "Bob Hancock" robert.hancock@........... Date: Sun, 8 Sep 2002 15:23:15 -0400 Something very big being recorded on east coat - Initial P wave at 1904 UTC __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: From: peaches@............ (Donna Whitaker) Date: Sun, 8 Sep 2002 09:29:09 -1000 (HST) Extremely large event comming in here in Hawaii. Some of the largest surface waves I've seen on this system. Looks larger than 7.4 from here. TO ALL TSUNAMI WARNING SYSTEM PARTICIPANTS SUBJECT: TSUNAMI INFORMATION BULLETIN BULLETIN NUMBER 1 WEST COAST AND ALASKA TSUNAMI WARNING CENTER/NOAA/NWS ISSUED 09/08/2002 AT 1907 UTC ....THIS TSUNAMI INFORMATION BULLETIN IS FOR ALASKA, BRITISH COLUMBIA, WASHINGTON, OREGON, AND CALIFORNIA ONLY... NO - REPEAT NO - WATCH OR WARNING IS IN EFFECT. EARTHQUAKE DATA: PRELIMINARY MAGNITUDE: 7.4 LOCATION: 3.3S 143.1E - NEAR N COAST OF NEW GUINEA, PNG. TIME: 1045 ADT 09/08/2002 1145 PDT 09/08/2002 1845 UTC 09/08/2002 EVALUATION: BASED ON LOCATION AND MAGNITUDE THE EARTHQUAKE WAS NOT SUFFICIENT TO GENERATE A TSUNAMI DAMAGING TO CALIFORNIA, OREGON, WASHINGTON, BRITISH COLUMBIA OR ALASKA. SOME AREAS MAY EXPERIENCE SMALL SEA LEVEL CHANGES. IN AREAS OF INTENSE SHAKING, LOCALLY GENERATED TSUNAMIS CAN BE TRIGGERED BY SLUMPING. THE PACIFIC TSUNAMI WARNING CENTER WILL ISSUE TSUNAMI BULLETINS FOR HAWAII AND OTHER AREAS OF THE PACIFIC. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: This just in... From: peaches@............ (Donna Whitaker) Date: Sun, 8 Sep 2002 09:45:55 -1000 (HST) From the Pacific Tsunami Warning Center in Ewa Beach. TSUNAMI BULLETIN NUMBER 002 PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS ISSUED 08 SEP, 1926 UTC THIS BULLETIN IS FOR ALL AREAS OF THE PACIFIC BASIN EXCEPT CALIFORNIA, OREGON, WASHINGTON, BRITISH COLUMBIA, AND ALASKA. .. . . A TSUNAMI WARNING AND WATCH ARE IN EFFECT . . . A TSUNAMI WARNING IS IN EFFECT FOR: BELAU, YAP, CHUUK, GUAM, POHNPEI, N. MARIANAS, KOSRAE A TSUNAMI WATCH IS IN EFFECT FOR: MARSHALL IS., PHILIPPINES, NAURU, MARCUS IS., WAKE IS., JAPAN, TAIWAN, NEW CALEDONIA FOR OTHER AREAS IN THE PACIFIC, THIS MESSAGE IS FOR INFORMATION ONLY. AN EARTHQUAKE, PRELIMINARY MAGNITUDE 7.6, OCCURRED 08 SEP, 1844 UTC. COORDINATES: LATITUDE 3.3 SOUTH, LONGITUDE 143.1 EAST VICINITY: NEAR N COAST OF NEW GUINEA, PNG.. EVALUATION: IT IS NOT KNOWN THAT A TSUNAMI WAS GENERATED. THIS WARNING AND WATCH ARE BASED ONLY ON EARTHQUAKE EVALUATION. ESTIMATED TIMES OF INITIAL WAVE ARRIVAL AT LOCATIONS WITHIN THE WARNING AND WATCH AREAS ARE: BELAU MALAKAL 2056Z 08 SEP YAP YAP IS. 2101Z 08 SEP CHUUK CHUUK IS. 2109Z 08 SEP GUAM GUAM 2131Z 08 SEP POHNPEI POHNPEI IS. 2146Z 08 SEP N. MARIANAS SAIPAN 2148Z 08 SEP KOSRAE KOSRAE IS. 2224Z 08 SEP MARSHALL IS. ENIWETOK 2233Z 08 SEP KWAJALEIN 2306Z 08 SEP MAJURO 2336Z 08 SEP PHILIPPINES LEGASPI 2259Z 08 SEP NAURU NAURU 2302Z 08 SEP MARCUS IS. MARCUS IS 2311Z 08 SEP WAKE IS. WAKE IS. 2331Z 08 SEP JAPAN OKINAWA 2340Z 08 SEP SHIMIZU 0038Z 09 SEP TAIWAN HUALIEN 2344Z 08 SEP NEW CALEDONIA NOUMEA 0026Z 09 SEP BULLETINS WILL BE ISSUED HOURLY OR SOONER IF CONDITIONS WARRANT. THE TSUNAMI WARNING WILL REMAIN IN EFFECT UNTIL FURTHER NOTICE. RECIPIENTS OF THIS MESSAGE LOCATED IN CALIFORNIA, OREGON, WASHINGTON, BRITISH COLUMBIA, AND ALASKA SHOULD REFER ONLY TO ALASKA TSUNAMI WARNING CENTER MESSAGES FOR INFORMATION ABOUT ANY TSUNAMI THREAT IN THOSE AREAS. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: BIG From: "Francesco" fra.nuc@........... Date: Sun, 8 Sep 2002 22:13:42 +0200 large superficial waves for about 50m here in Italy, Pn at 19.04utc Francesco __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: BIG From: Hammonds hammond@........... Date: Sun, 08 Sep 2002 12:18:35 -0800 Got it here nicely. This is the 1 hz filtered record: http://apsn.awcable.com/020908.gif Bob Hammond Alaska Public Seismic Network http://apsn.awcable.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: This just in... From: David A Nelson davenn@............... Date: Mon, 09 Sep 2002 06:54:46 +1000 A magnitude 7.5 earthquake NEAR THE N COAST NEW GUINEA, PNG. has occurred at: 3.23S 142.87E Depth 33km Sun Sep 8 18:44:26 2002 UTC Time: Universal Time (UTC) Sun Sep 8 18:44:26 2002 Eastern Daylight Time (EDT) Sun Sep 8 14:44:26 2002 Central Daylight Time (CDT) Sun Sep 8 13:44:26 2002 Mountain Daylight Time (MDT) Sun Sep 8 12:44:26 2002 Pacific Daylight Time (PDT) Sun Sep 8 11:44:26 2002 Alaska Daylight Time (ADT) Sun Sep 8 10:44:26 2002 Hawaii Standard Time (HST) Sun Sep 8 08:44:26 2002 right on the Nth coast of Papua New Guinea cheers all Dave __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: RECORDING EARTHQUAKES WITH EMON7 From: RADIOTEL@....... Date: Sun, 8 Sep 2002 21:17:58 EDT I am using Emon7 for recording earthquakes and It does a good job. However, when I record a fairly large or long earthquake such as the one in New Guinea, it records and saves it over about three screens so when I print it out I have to actually print out three records. In attempting to alleivate this problem, I set my sampling rate to 7.3 sps which is the minimum that it will accept on my computer which is a pentium. Any ideas that someone would have to allow me to capture an entire quake on one record would be appreciated. James Allen Cerritos, Ca. I am using Emon7 for recording earthquakes and It does a good job.  However, when I record a fairly large or long earthquake such as the one in New Guinea, it records and saves it over about three screens so when I print it out I have to actually print out three records.  In attempting to alleivate this problem, I set my sampling rate to 7.3 sps which is the minimum that it will accept on my computer which is a pentium.
Any ideas that someone would have to allow me to capture an entire quake on one record would be appreciated.
James Allen
Cerritos, Ca.
Subject: Re: RECORDING EARTHQUAKES WITH EMON7 From: "Randall Pratt" randallpratts@.......... Date: Sun, 8 Sep 2002 20:29:56 -0500 James, You can use a program called msplice.exe to merge multiple files into = one. I used it again today for the big one. It comes with the = quakeview program package which I think is still available on the PSN = site. The only drawback is a 25000 sample limit. It will drop every = nth sample to remain within the limit. If you do a file save of view = only in Winquake you can reduce sample numbers from the ends of both = files before the merge and usually fit two files without loosing data. = Good luck. Randy ----- Original Message -----=20 From: RADIOTEL@.......... To: psn-l@................. Sent: Sunday, September 08, 2002 8:17 PM Subject: Re: RECORDING EARTHQUAKES WITH EMON7 I am using Emon7 for recording earthquakes and It does a good job. = However, when I record a fairly large or long earthquake such as the one = in New Guinea, it records and saves it over about three screens so when = I print it out I have to actually print out three records. In = attempting to alleivate this problem, I set my sampling rate to 7.3 sps = which is the minimum that it will accept on my computer which is a = pentium. Any ideas that someone would have to allow me to capture an entire = quake on one record would be appreciated. James Allen Cerritos, Ca.
James,
 
You can use a program called = msplice.exe to merge=20 multiple files into one.  I used it again today for the big = one.  It=20 comes with the quakeview program package which I think is still = available on the=20 PSN site.  The only drawback is a 25000 sample limit.  It will = drop every nth sample to remain = within the=20 limit.  If you do a file save of view only in Winquake you can = reduce=20 sample numbers from the ends of both files before the merge and usually = fit two=20 files without loosing data.  Good luck.
 
Randy
 
----- Original Message -----
From:=20 RADIOTEL@.......=20
Sent: Sunday, September 08, = 2002 8:17=20 PM
Subject: Re: RECORDING = EARTHQUAKES WITH=20 EMON7

I am using = Emon7 for=20 recording earthquakes and It does a good job.  However, when I = record a=20 fairly large or long earthquake such as the one in New Guinea, it = records and=20 saves it over about three screens so when I print it out I have to = actually=20 print out three records.  In attempting to alleivate this = problem, I set=20 my sampling rate to 7.3 sps which is the minimum that it will accept = on my=20 computer which is a pentium.
Any ideas that someone would have to = allow me=20 to capture an entire quake on one record would be = appreciated.
James=20 Allen
Cerritos, Ca.
Subject: RE: RECORDING EARTHQUAKES WITH EMON7 From: steve hammond shammon1@............. Date: Mon, 9 Sep 2002 00:47:42 -0700 I have the msplice, EL and emon packages if you need them. Regards, Steve Hammond PSN San Jose. -----Original Message----- From: Randall Pratt [SMTP:randallpratts@........... Sent: Sunday, September 08, 2002 6:30 PM To: psn-l@.............. Subject: Re: RECORDING EARTHQUAKES WITH EMON7 James, You can use a program called msplice.exe to merge multiple files into one. I used it again today for the big one. It comes with the quakeview program package which I think is still available on the PSN site. The only drawback is a 25000 sample limit. It will drop every nth sample to remain within the limit. If you do a file save of view only in Winquake you can reduce sample numbers from the ends of both files before the merge and usually fit two files without loosing data. Good luck. Randy ----- Original Message ----- From: RADIOTEL@....... To: psn-l@.............. Sent: Sunday, September 08, 2002 8:17 PM Subject: Re: RECORDING EARTHQUAKES WITH EMON7 I am using Emon7 for recording earthquakes and It does a good job. However, when I record a fairly large or long earthquake such as the one in New Guinea, it records and saves it over about three screens so when I print it out I have to actually print out three records. In attempting to alleivate this problem, I set my sampling rate to 7.3 sps which is the minimum that it will accept on my computer which is a pentium. Any ideas that someone would have to allow me to capture an entire quake on one record would be appreciated. James Allen Cerritos, Ca. << File: ATT00003.html >> __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Sensor directional alignment From: "Jonathan Peakall" jpeakall@............ Date: Mon, 9 Sep 2002 07:00:36 -0700 Hi All, Thanks for all the help, the cheap elementary school station slowly progresses. I have been looking around to try to determine the prevailing direction of earthquakes in my area, so as to set up my new directional sensor in the best direction. I live in Albion, California, 39deg,12.83", 123deg, 41.705". As I have the San Andreas fault line SSE of me, is NNW a good direction for my sensor? Perhaps just north? This sensor is remaining at home, not traveling to schools, and I am going to cast it on site into a concrete puddle, so it would be nice to get it in the right direction! Regards, Jonathan Peakall www.madlabs.info __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Sensor directional alignment From: "a.rodriguez" stuff@................. Date: Mon, 9 Sep 2002 09:35:00 -0500 Hello Jonathan, I would just make it a north / south sensor. I assume that you have a Lehman type sensor, a long period. Most likely you will detect events from all directions to some extent and the far away event will come from the Pacific. For those the boom point north will probably be best. Mostly I would not worry too much about it. Warmly, Angel Monday, September 9, 2002, 9:00:36 AM, you wrote: JP> Hi All, JP> Thanks for all the help, the cheap elementary school station slowly JP> progresses. I have been looking around to try to determine the prevailing JP> direction of earthquakes in my area, so as to set up my new directional JP> sensor in the best direction. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Papua New Guinea tsunami photo From: Seisguy@....... Date: Mon, 9 Sep 2002 15:02:45 EDT Interesting! http://www.sky.com/skynews/article/0,,30200-12115634,00.html Interesting!

http://www.sky.com/skynews/article/0,,30200-12115634,00.html
Subject: Re: Papua New Guinea tsunami From: hammond@........... Date: Mon, 9 Sep 2002 14:08:50 -0800 You can also see the tsunami on the Manus, Papua New Guinea tide gauge at: http://www.ntf.flinders.edu.au/TEXT/PRJS/NRTM/ONLINE/pn-m.html Choose Sea Level - A and better hurry, it's about to scroll off their near real time tide display. Look at about 2030 UTC. Bob Hammond APSN http://apsn.awcable.com ___________________________________ NOCC, http://nocc.sourceforge.net __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Preamp/Filter Board For Sale From: "Michael McCarty" mmccarty@.......... Date: Tue, 10 Sep 2002 19:17:20 -0600 I have one of Larry Cochrane's Lehman sensor preamp/filter boards for sale. It is a three channel board and comes with wall wart power supply, pickup coil and magnet as sold by Mr Cochrane. This is not the current board that he sells, but is marked REV D 1997. Please send offer to mmccarty@.......... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismic "Hookup" From: John & Jan johnjan@........ Date: Tue, 10 Sep 2002 22:36:00 -0600 Hi  Bob,

I've added the message below to the information that I'm gathering for the Colorado
School of Mines students who are working on designing an inexpensive sensor.  I hope
that is OK with you.

See the link under AD's on this page:
http://www.jjlahr.com/science/psn/epics/links.html

Cheers,
John

At 12:45 AM 9/6/2002 -0400, you wrote:
Hi Ed,

  I use the DI-194RS and the DI-154RS for seismic recording.  The DI-154 is preferable over the DI-194 because it has 12-bit A/D conversion, but at the same time, it costs $150 compared to the $25 paid for the RS-194.  It will work with your setup, I believe, but your preamp should have a full scale range of +/- 10 volts in order to get all of the dynamic range available from the Dataq starter kit.

  The Dataq unit samples at a fixed rate of 240 samples per second, but records at any desired rate that is an integer divide of 240.  All of the acquired data is input signal averaged, which improves resolution, increases signal-to-noise ratio, attenuates aliasing, and totally rejects 60 Hz and 120 Hz hum.  For example, I usually record at 5 samples per second.  During the 0.2 second sample interval, 48 data samples taken at the 240 samples per second rate are averaged to yield the recorded sample.

  The data is resolved to 14 bits.  The lower 2 bits of the data word are reserved for marker bits, such as time marks.  I equipped a WWVB wall clock with an optical pickoff to mark my recordings at a once-per-minute rate.

  I developed a drum plot program for display and filtering of recorded data.  This program can run simultaneously with the Dataq recorder and display data from the file as it is being recorded.  It can output filtered versions of the original file.  I find the "Broadband" filter to be most useful, since it extends the usual response of my 3.4 second seismometer out to periods of 20 seconds or more.  It is available for downloading from the Dataq web site.  It is also on the installation disc for the Dataq Lite Software, in the catalog section.

Regards,

Bob McClure
Subject: "EPICS" seismo suggestion From: meredithlamb meredithlamb@............. Date: Fri, 13 Sep 2002 16:02:13 -0600 Hi all, I would suggest "S-G's" (Shackelford-Gunderson) type seismo's as being perhaps the easiest to build. They simply are pendulums that hang downward, and have used a variety of sensors that I've noted. These are horizontal sensitive instruments. About the most important part mechanically seems to have been just the 0.001" thick X ~1.5" length brass hinge/s I used; it seemed to need the flexibility there for longer period (electronic capacitive storage) response to distant quake phases with periods ranging up to > ~30 seconds. I've little electronics experience per'se, but the Hall sensor type designed by my (deceased) brother Robert back in ~ 1997, seems to be another design that any interested partys might wish to review.... if for nothing more than the basic simpicity of the mechanical design....it doesn't have to exotic....just mechanically stout. Robert Lamb was a electronics engineer for H-P and Texas Nuclear. Perhaps the biggest negative is the Hall sensors generate more "noise" than is desired. Being as the Hall S-G is a stable gravity related instrument, I've seen that after construction and a reasonable period of mechanical settling in time, that its been much more dependable than any of my Sprengnethers and their "hanging gate" pendulums for temperature and even moreso for ground water related tilt effects tolerance. I do suggest that any replicators have a fair degree of electronics knowledge...even though the circuit is not excessively complicated. Its likely the majority cost expense will be with the Hall circuit itself. The circuit/instrument was designed to be a simple (comparisons) general instrument, with none of the extreme complexities that alot of manufacturers seismo's and circuits claim to attain. http://www.geocities.com/meredithlamb/index.html Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: new addition to the list From: David A Nelson davenn@............... Date: Mon, 16 Sep 2002 19:43:11 +1000 hi all, A warm welcome Bob Hancock of New Jersey to the PSN the latest one to be added to the map and database hope u enjoy ur time with the group Bob Cheers Dave __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: "EPICS" seismo suggestion From: ChrisAtUpw@....... Date: Mon, 16 Sep 2002 05:55:22 EDT In a message dated 13/09/02, meredithlamb@............. writes: > I would suggest "S-G's" (Shackelford-Gunderson) type seismo's as being > perhaps the easiest to build. They simply are pendulums that hang > downward, and have used a variety of sensors that I've noted. These are > horizontal sensitive instruments. About the most important part > mechanically seems to have been just the 0.001" thick X ~1.5" length brass > hinge/s I used; it seemed to need the flexibility there for longer period > (electronic capacitive) response to distant quake phases with periods > ranging up to > ~30 seconds. > > I've little electronics experience per'se, but the Hall sensor type > designed by my (deceased) brother Robert back in ~1997, seems to be another > design that any interested partys might wish to review.... if for nothing > more than the basic simpicity of the mechanical design.... > Being as the Hall S-G is a stable gravity related instrument, I've seen > that after construction and a reasonable period of mechanical settling in > time, that its been much more dependable than any of my Sprengnethers and > their "hanging gate" pendulums for temperature and even moreso for ground > water related tilt effects tolerance. > > http://www.geocities.com/meredithlamb/index.html The resolution and the linearity that you can get from a $1.83 A3515LUA sensor from http://www.newark.com/ and a $2 type #2 NdBFe four pole magnet from www.wondermagnet.com are really quite good. The minimum movement which can be measured depends on the sensitivity and on the noise level present on the output signal. With a three pole 10 Hz Butterworth filter and the NdBFe magnets set for a sensitivity of 5.8 mV / micron, an A3515 sensor gave a bit under +/-20 nano metres resolution and the linear range of 0.8 mm. If I increased the sensitivity to 10 mV / micron by adjusting the magnetic field, I got down to about +/-10 nano metres resolution, but I had only ~0.5 mm total linear range. This is still OK for a pendulum sensor. See http://mariottim.interfree.it/doc11_e.htm for a typical calibration graph and some further notes on these sensors. Regards, Chris Chapman In a message dated 13/09/02, meredithlamb@............. writes:

I would suggest "S-G's" (Shackelford-Gunderson) type seismo's as being perhaps the easiest to build.  They simply are pendulums that hang downward, and have used a variety of sensors that I've noted. These are horizontal sensitive instruments.  About the most important part mechanically seems to have been just the 0.001" thick X ~1.5" length brass hinge/s I used; it seemed to need the flexibility there for longer period (electronic capacitive) response to distant quake phases with periods ranging up to > ~30 seconds.

I've little electronics experience per'se, but the Hall sensor type designed by my (deceased) brother Robert back in ~1997, seems to be another design that any interested partys might wish to review.... if for nothing more than the basic simpicity of the mechanical design....
Being as the Hall S-G is a stable gravity related instrument, I've seen that after construction and a reasonable period of mechanical settling in time, that its been much more dependable than any of my Sprengnethers and their "hanging gate" pendulums for temperature and even moreso for ground water related tilt effects tolerance.

http://www.geocities.com/meredithlamb/index.html


      The resolution and the linearity that you can get from a $1.83 A3515LUA sensor from http://www.newark.com/ and a $2 type #2 NdBFe four pole magnet from www.wondermagnet.com are really quite good.

    The minimum movement which can be measured depends on the sensitivity and on the noise level present on the output signal. With a three pole 10 Hz Butterworth filter and the NdBFe magnets set for a sensitivity of 5.8 mV / micron, an A3515 sensor gave a bit under +/-20 nano metres resolution and the linear range of 0.8 mm. If I increased the sensitivity to 10 mV / micron by adjusting the magnetic field, I got down to about +/-10 nano metres resolution, but I had only ~0.5 mm total linear range. This is still OK for a pendulum sensor.

    See http://mariottim.interfree.it/doc11_e.htm for a typical calibration graph and some further notes on these sensors.

    Regards,

    Chris Chapman
Subject: Re: "EPICS" seismo suggestion From: ChrisAtUpw@....... Date: Mon, 16 Sep 2002 13:15:42 EDT In a message dated 13/09/02, meredithlamb@............. writes: > I would suggest "S-G's" (Shackelford-Gunderson) type seismo's as being > perhaps the easiest to build. They simply are pendulums that hang > downward, and have used a variety of sensors that I've noted. These are > horizontal sensitive instruments. About the most important part > mechanically seems to have been just the 0.001" thick X ~1.5" length brass > hinge/s I used; it seemed to need the flexibility there for longer period > (electronic capacitive) response to distant quake phases with periods > ranging up to > ~30 seconds. > > I've little electronics experience per'se, but the Hall sensor type > designed by my (deceased) brother Robert back in ~1997, seems to be another > design that any interested partys might wish to review.... if for nothing > more than the basic simpicity of the mechanical design.... > Being as the Hall S-G is a stable gravity related instrument, I've seen > that after construction and a reasonable period of mechanical settling in > time, that its been much more dependable than any of my Sprengnethers and > their "hanging gate" pendulums for temperature and even moreso for ground > water related tilt effects tolerance. > > http://www.geocities.com/meredithlamb/index.html The resolution and the linearity that you can get from a $1.83 A3515LUA sensor from http://www.newark.com/ and a $2 type #2 NdBFe four pole magnet from www.wondermagnet.com are really quite good. The minimum movement which can be measured depends on the sensitivity and on the noise level present on the output signal. With a three pole 10 Hz Butterworth filter and the NdBFe magnets set for a sensitivity of 5.8 mV / micron, an A3515 sensor gave a bit under +/-20 nano metres resolution and the linear range of 0.8 mm. If I increased the sensitivity to 10 mV / micron by adjusting the magnetic field, I got down to about +/-10 nano metres resolution, but I had only ~0.5 mm total linear range. This is still OK for a pendulum sensor. See http://mariottim.interfree.it/doc11_e.htm for a typical calibration graph and some further notes on these sensors. Regards, Chris Chapman In a message dated 13/09/02, meredithlamb@............. writes:

I would suggest "S-G's" (Shackelford-Gunderson) type seismo's as being perhaps the easiest to build.  They simply are pendulums that hang downward, and have used a variety of sensors that I've noted. These are horizontal sensitive instruments.  About the most important part mechanically seems to have been just the 0.001" thick X ~1.5" length brass hinge/s I used; it seemed to need the flexibility there for longer period (electronic capacitive) response to distant quake phases with periods ranging up to > ~30 seconds.

I've little electronics experience per'se, but the Hall sensor type designed by my (deceased) brother Robert back in ~1997, seems to be another design that any interested partys might wish to review.... if for nothing more than the basic simpicity of the mechanical design....
Being as the Hall S-G is a stable gravity related instrument, I've seen that after construction and a reasonable period of mechanical settling in time, that its been much more dependable than any of my Sprengnethers and their "hanging gate" pendulums for temperature and even moreso for ground water related tilt effects tolerance.

http://www.geocities.com/meredithlamb/index.html


     The resolution and the linearity that you can get from a $1.83 A3515LUA sensor from http://www.newark.com/ and a $2 type #2 NdBFe four pole magnet from www.wondermagnet.com are really quite good.

   The minimum movement which can be measured depends on the sensitivity and on the noise level present on the output signal. With a three pole 10 Hz Butterworth filter and the NdBFe magnets set for a sensitivity of 5.8 mV / micron, an A3515 sensor gave a bit under +/-20 nano metres resolution and the linear range of 0.8 mm. If I increased the sensitivity to 10 mV / micron by adjusting the magnetic field, I got down to about +/-10 nano metres resolution, but I had only ~0.5 mm total linear range. This is still OK for a pendulum sensor.

   See http://mariottim.interfree.it/doc11_e.htm for a typical calibration graph and some further notes on these sensors.

   Regards,

   Chris Chapman
Subject: Re: "EPICS" seismo suggestion From: meredithlamb meredithlamb@............. Date: Mon, 16 Sep 2002 21:35:21 -0600 Hi Chris and all, Chris's sensitive "distance calibrator" that was used for his Hall sensor/s, output graph measurements can be seen at: http://seismograph.tripod.com/distancecalibrator.html It was very well crafted by Chris himself, and well worth a peek. Take care, Meredith Lamb ChrisAtUpw@....... wrote: > The resolution and the linearity that you can get from a $1.83 > A3515LUA sensor from http://www.newark.com/ and a $2 type #2 NdBFe > four pole magnet from www.wondermagnet.com are really quite good. > > The minimum movement which can be measured depends on the > sensitivity and on the noise level present on the output signal. With > a three pole 10 Hz Butterworth filter and the NdBFe magnets set for a > sensitivity of 5.8 mV / micron, an A3515 sensor gave a bit under +/-20 > nano metres resolution and the linear range of 0.8 mm. If I increased > the sensitivity to 10 mV / micron by adjusting the magnetic field, I > got down to about +/-10 nano metres resolution, but I had only ~0.5 mm > total linear range. This is still OK for a pendulum sensor. > > See http://mariottim.interfree.it/doc11_e.htm for a typical > calibration graph and some further notes on these sensors. > > Regards, > > Chris Chapman Hi Chris and all,

Chris's sensitive "distance calibrator" that was used for his Hall
sensor/s, output graph measurements can be seen at:

http://seismograph.tripod.com/distancecalibrator.html

It was very well crafted by Chris himself, and well worth a peek.

Take care, Meredith Lamb

ChrisAtUpw@....... wrote:

The resolution and the linearity that you can get from a $1.83 A3515LUA sensor from http://www.newark.com/ and a $2 type #2 NdBFe four pole magnet from www.wondermagnet.com are really quite good.

    The minimum movement which can be measured depends on the sensitivity and on the noise level present on the output signal. With a three pole 10 Hz Butterworth filter and the NdBFe magnets set for a sensitivity of 5.8 mV / micron, an A3515 sensor gave a bit under +/-20 nano metres resolution and the linear range of 0.8 mm. If I increased the sensitivity to 10 mV / micron by adjusting the magnetic field, I got down to about +/-10 nano metres resolution, but I had only ~0.5 mm total linear range. This is still OK for a pendulum sensor.

    See http://mariottim.interfree.it/doc11_e.htm for a typical calibration graph and some further notes on these sensors.

    Regards,

    Chris Chapman

Subject: Re: "EPICS" seismo suggestion From: "Charles R. Patton" charles.r.patton@........ Date: Mon, 16 Sep 2002 21:51:37 -0700 Aa a sensor solution for the SG seimo, it was proposed to use "=85a $1.83= A3515LUA sensor=85" So this brings up this thought: Most standard IC frames are magnetic - consisting of a Kovar frame. And magnetic sensors in particular are often constructed with "magnetic concentrators" to focus magnetic flux on to the sensitive area of the chip. Both make the chip physically attracted to ambient fields. If the chip is not mounted on the SG arm, then the magnets must be, which would be even worse about ambient sensitivity. So if one goes for the higher sensitivity of the SG, doesn't this create problems in terms of an actual physical sensitivity to the surrounding changing magnetic fields? I'm thinking back to some experiments that Roger Baker did on magnetometers in which his magnetometer is actually a magnet on a torsion balance. He said he could detect a small magnet many feet away and I know he could sense geomagnetic changes. It would seem to me that would turn the SG seismo into a geomagnetic field detector. Roger's detectors were based on photodetectors and LED or Laser LED sources. I think I'd vote for the original SG variable capacitance detector. = Today you can buy ICs which do all the detection. For one source see "Universal Capacitive ReadoutTM IC (MS3110)" at: http://www.microsensors.com/products.html I don't know how much it costs, but in volume this can't be that expensive. I also know there is at least a couple of European companies that makes a similar IC. = Just some idle musings. Regards, Charles R. Patton __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: "EPICS" seismo suggestion From: ChrisAtUpw@....... Date: Tue, 17 Sep 2002 15:19:17 EDT In a message dated 17/09/02, charles.r.patton@........ writes: Hi Charles, > A sensor solution for the SG seimo, it was proposed to use "=E2=80=A6a $1.= 83 > A3515LUA sensor=E2=80=A6" >=20 > So this brings up this thought: Most standard IC frames are magnetic - > consisting of a Kovar frame. =20 This one is non magnetic. And magnetic sensors in particular are o > ften constructed with "magnetic concentrators" to focus magnetic flux on t= o=20 > the sensitive area of the chip. =20 No ferrite or other concentrator is used. Both make the chip physically=20 > attracted to ambient fields. =20 There is NO PROBLEM in this case. Didn't you check the data sheet?=20 =20 If the chip is not mounted on the SG arm,=20 > then the magnets must be, which would be even worse about ambient=20 > sensitivity. So if one goes for the higher sensitivity of the SG, doesn't= =20 > this create problems in terms of an actual physical sensitivity > to the surrounding changing magnetic fields? =20 No. You can get problems if you fail to take sensible design=20 precautions, or do something real dumb. The field generated by these magnets= =20 is basically quadrupole, not dipole. It is quite easy to shield the magnet(s= )=20 and the sensor with a U of mild steel and even easier to use two flat plates= =20 and two separators. Allegro show suitable shielded sensor housings in their=20 applications sheet. The high sensitivity arises from the intense fields clos= e=20 to the surface of the NdBFe magnets, usually mounted within a shield housing= ..=20 The A3515 has a typical sensitivity of 5 mV / gauss, so stray earth fields=20 are not generally a problem and definitely not when it is shielded. =20 I'm thinking back to some=20 > experiments that Roger Baker did on magnetometers in which his magnetomete= r=20 >=20 ????? I am definitely NOT Roger Baker and this is definitely NOT a=20 magnetometer application!=20 >=20 While this may be very interesting, how is it relevant to an A3515=20 magnetic sensor, please?=20 >=20 This ancient design uses ferrite tuned circuits and diode=20 rectification, both of which are inherently temperature sensitive, very much= =20 so in the case of the diodes. This type of sensor was dropped by=20 seismologists well over 20 years ago for output drift problems, amongst=20 others. Can you provide any experimental noise and thermal stability=20 measurements for such a system, to back up your 'vote' decision, please? =20 Today you can buy ICs which do all the detection. For one source see=20 "Universal=20 > Capacitive ReadoutTM IC (MS3110)" at:=20 > http://www.microsensors.com/products.html > I don't know how much it costs, but in volume this can't be that expensive= ..=20 > I also know there is at least a couple of European companies that makes a= =20 >=20 The MS3110 is supplied in 16 pin surface mount SOIC housing with a 5=20= V=20 supply. You can either program the chip ROM of you can input serial data into= =20 the chip, otherwise you can't use it.=20 The minimum output filter frequency is 500 Hz, two pole. There is no drive provided for a screen for an input sensor wire /=20 line. The dynamic range does not seem to be quoted. It is very often 10^-4=20 in commercial devices which use this type of sensor, like the ADXL05. While=20 this is fine for airbag control on cars, seismic sensor applications require= =20 a greater dynamic range.=20 You can buy a MS3110 development board with 5 SOIC devices for $199.=20 This enables you to programme SOIC chips. The minimum order quantity for the= =20 MS3110 is 25 off at $13-64 each. With these limitations, how do you suggest that the MS3110 could be=20 applied to our amateur seismic equipment, please? I fully appreciate that=20 capacitative sensors can give superb results, but this device does not quite= =20 look a 'first choice' for amateur use. What other companies are producing devices similar to the MS3110,=20 please? Regards, Chris Chapman =20 > Aa a sensor solution for the SG seimo, it was proposed to use "=E2=80=A6a=20= $1.83 > A3515LUA sensor=E2=80=A6" >=20 > So this brings up this thought: Most standard IC frames are magnetic -=20 > consisting of a Kovar frame. And magnetic sensors in particular are often= =20 > constructed with "magnetic concentrators" to focus magnetic flux on to the= =20 > sensitive area of the chip. Both make the chip physically attracted to=20 > ambient fields. If the chip is not mounted on the SG arm, then the magnet= s=20 > must be, which would be even worse about ambient sensitivity. So if one=20 > goes for the higher sensitivity of the SG, > doesn't this create problems in terms of an actual physical sensitivity to= =20 > the surrounding changing magnetic fields? I'm thinking back to some=20 > experiments that Roger Baker did on magnetometers in which his magnetomete= r=20 > is actually a magnet on a torsion balance. He said he could detect a small= =20 > magnet many feet away and I know he could sense geomagnetic changes. It=20 > would seem to me that would turn the SG seismo into a geomagnetic field=20 > detector. Roger's detectors were based on photodetectors and LED or Laser=20 > LED sources. >=20 > I think I'd vote for the original SG variable capacitance detector.=20 > Today you can buy ICs which do all the detection. For one source see > "Universal Capacitive ReadoutTM IC (MS3110)" at: > http://www.microsensors.com/products.html > I don't know how much it costs, but in volume this can't be that expensive= ..=20 > I also know there is at least a couple of European companies that makes a= =20 > similar IC.=20 > Regards, >=20 In a message dated 17/09/= 02, charles.r.patton@........ writes:

Hi Charles,

A sensor solution for the S= G seimo, it was proposed to use "=E2=80=A6a $1.83
A3515LUA sensor=E2=80= =A6"

So this brings up this thought: Most standard IC frames are magn= etic -
consisting of a Kovar frame.  


      This one is non magnetic.

And magnetic sensors in particular are o
ften constructed with "magn= etic concentrators" to focus magnetic flux on to the sensitive area of the c= hip.  


      No ferrite or other concentrator is= used.

Both make the chip physically=20
attracted to ambient fields= ..  


      There is NO PROBLEM in this case. D= idn't you check the data sheet?=20
=20
If the chip is not mounted on the SG arm,=20
then the magnets must be, w= hich would be even worse about ambient sensitivity.  So if one goes for= the higher sensitivity of the SG, doesn't this create problems in terms of=20= an actual physical sensitivity
to the surrounding changing magnetic fields?  


      No. You can get problems if you fai= l to take sensible design precautions, or do something real dumb. The field=20= generated by these magnets is basically quadrupole, not dipole. It is quite=20= easy to shield the magnet(s) and the sensor with a U of mild steel and even=20= easier to use two flat plates and two separators. Allegro show suitable shie= lded sensor housings in their applications sheet. The high sensitivity arise= s from the intense fields close to the surface of the NdBFe magnets, usually= mounted within a shield housing. The A3515 has a typical sensitivity of 5 m= V / gauss, so stray earth fields are not generally a problem and definitely=20= not when it is shielded.  

I'm thinking back to some=20
experiments that Roger Bake= r did on magnetometers in which his magnetometer is actually a magnet on a t= orsion balance.


      ????? I am definitely NOT Roger Bak= er and this is definitely NOT a magnetometer application!=20

Roger's detectors were bas= ed on photodetectors and LED or Laser LED sources.


      While this may be very interesting,= how is it relevant to an A3515 magnetic sensor, please?=20

I think I'd vote for the or= iginal SG variable capacitance detector.


      This ancient design uses ferrite tu= ned circuits and diode rectification, both of which are inherently temperatu= re sensitive, very much so in the case of the diodes. This type of sensor wa= s dropped by seismologists well over 20 years ago for output drift problems,= amongst others. Can you provide any experimental noise and thermal stabilit= y measurements for such a system, to back up your 'vote' decision, please?
=20
Today you can buy ICs which do all the detection.  For one source s= ee "Universal=20
Capacitive ReadoutTM IC (MS= 3110)" at: http://www.microsensors.com/products.html
I don't know how much it costs, but in volume this can't be that expensi= ve.  I also know there is at least a couple of European companies that=20= makes a similar IC.


      The MS3110 is supplied in 16 pin su= rface mount SOIC housing with a 5 V supply.
      You can either program the chip ROM= of you can input serial data into the chip, otherwise you can't use it.=20
      The minimum output filter frequency= is 500 Hz, two pole.
      There is no drive provided for a sc= reen for an input sensor wire / line.
      The dynamic range does not seem to=20= be quoted. It is very often 10^-4 in commercial devices which use this type=20= of sensor, like the ADXL05. While this is fine for airbag control on cars, s= eismic sensor applications require a greater dynamic range.=20

      You can buy a MS3110 development bo= ard with 5 SOIC devices for $199. This enables you to programme SOIC chips.=20= The minimum order quantity for the MS3110 is 25 off at $13-64 each.

      With these limitations, how do you=20= suggest that the MS3110 could be applied to our amateur seismic equipment, p= lease? I fully appreciate that capacitative sensors can give superb results,= but this device does not quite look a 'first choice' for amateur use.

      What other companies are producing=20= devices similar to the MS3110, please?

      Regards,

      Chris Chapman
      
Aa a sensor solution for th= e SG seimo, it was proposed to use "=E2=80=A6a $1.83
A3515LUA sensor=E2= =80=A6"

So this brings up this thought:  Most standard IC frames= are magnetic - consisting of a Kovar frame.  And magnetic sensors in p= articular are often constructed with "magnetic concentrators" to focus magne= tic flux on to the sensitive area of the chip.  Both make the chip phys= ically attracted to ambient fields.  If the chip is not mounted on the=20= SG arm, then the magnets must be, which would be even worse about ambient se= nsitivity. So if one goes for the higher sensitivity of the SG,
doesn't this create problems in terms of an actual physical sensitivity=20= to the surrounding changing magnetic fields? I'm thinking back to some exper= iments that Roger Baker did on magnetometers in which his magnetometer is ac= tually a magnet on a torsion balance. He said he could detect a small magnet= many feet away and I know he could sense geomagnetic changes. It would seem= to me that would turn the SG seismo into a geomagnetic field detector. Roge= r's detectors were based on photodetectors and LED or Laser LED sources.

I think I'd vote for the original SG variable capacitance detector.=20
Today you can buy ICs which do all the detection.  For one source s= ee
"Universal Capacitive ReadoutTM IC (MS3110)" at:
http://www.microsensors.com/products.html
I don't know how much it costs, but in volume this can't be that expensi= ve.  I also know there is at least a couple of European companies that=20= makes a similar IC.=20
Regards,
Charles R. Patton

Subject: Re: "EPICS" seismo suggestion From: Thomas W Leiper twleiper@........ Date: Tue, 17 Sep 2002 18:37:34 -0400 Seems to be an all-out nuclear exchange between academicians... Let me know when the radiation has dropped top safe levels so I can come up from the bomb shelter and survey the wasteland. Maybe I'll even offer up how to make an incredible, virtually unlimited dynamic range, drift-free capacitive force-balanced system for peanuts. Tom On Tue, 17 Sep 2002 15:19:17 EDT ChrisAtUpw@....... writes: [edited for maximum impact] There is NO PROBLEM in this case. Didn't you check the data sheet? ????? I am definitely NOT Roger Baker and this is definitely NOT a magnetometer application! While this may be very interesting, how is it relevant to an A3515 magnetic sensor, please? Can you provide any experimental noise and thermal stability measurements for such a system, to back up your 'vote' decision, While this is fine for airbag control on cars, seismic sensor applications require a greater dynamic range. With these limitations, how do you suggest that the MS3110 could be applied to our amateur seismic equipment, please? =EF=BB=BF
Seems to be an all-out nuclear exchange between academicians...
 
Let me know when the radiation has dropped top safe levels so I can
come up from the bomb shelter and survey the wasteland. Maybe=20 I'll
even offer up how to make an incredible, virtually unlimited=20 dynamic
range, drift-free capacitive force-balanced system for peanuts.
 
Tom
 
On Tue, 17 Sep 2002 15:19:17 EDT ChrisAtUpw@....... writes:
[edited for maximum=20 impact]    
There is NO PROBLEM in = this case.=20 Didn't you check the data sheet? 
????? I am definitely NOT Roger= =20 Baker and this is definitely NOT a magnetometer application! 
= While=20 this may be very interesting, how is it relevant to an A3515 magnetic = sensor,=20 please? 
Can you provide any experimental noise and thermal = stability=20 measurements for such a system, to back up your 'vote'=20 decision,
While this is fine for = airbag=20 control on cars, seismic sensor applications require a greater dynamic=20 range. 
With these limitations, how do you suggest that the = MS3110=20 could be applied to our amateur seismic equipment, please?
<= FONT=20 face=3Darial,helvetica>
Subject: Re: "EPICS" seismo suggestion From: John & Jan johnjan@........ Date: Tue, 17 Sep 2002 18:38:33 -0600 Hi Tom, I'll bite. How is it done? Thanks, John At 06:37 PM 9/17/2002 -0400, you wrote: >Maybe I'll >even offer up how to make an incredible, virtually unlimited dynamic >range, drift-free capacitive force-balanced system for peanuts. * John C. and Jan H. Lahr * JohnJan@........ * 1925 Foothills Road * Golden, Colorado 80401-1718 * Phone: (303) 215-9913 * http://jjlahr.com/science/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: "EPICS" seismo suggestion From: ChrisAtUpw@....... Date: Tue, 17 Sep 2002 20:43:20 EDT In a message dated 17/09/02, twleiper@........ writes: > Maybe I'll even offer up how to make an incredible, virtually unlimited > dynamic > range, drift-free capacitive force-balanced system for peanuts. Hi Tom, I am always willing to listen! But are they genetically modified peanuts? Regards, Chris Chapman In a message dated 17/09/02, twleiper@........ writes:

Maybe I'll even offer up how to make an incredible, virtually unlimited dynamic
range, drift-free capacitive force-balanced system for peanuts.


Hi Tom,

      I am always willing to listen!

      But are they genetically modified peanuts?

      Regards,

      Chris Chapman
Subject: Re: "EPICS" seismo suggestion From: Thomas W Leiper twleiper@........ Date: Tue, 17 Sep 2002 22:48:26 -0400 Last time I checked under my shorts...they weren't. The view through the periscope appears safe, although it is a bit early in the fall for the trees to be denuded. In any event, I'll prepare a treatise on the syncronous detector and launch it post haste... Dr. Strangelove On Tue, 17 Sep 2002 20:43:20 EDT ChrisAtUpw@....... writes: But are they genetically modified peanuts? Regards, Chris Chapman
Last time I checked under my shorts...they weren't.
 
The view through the periscope appears safe, although
it is a bit early in the fall for the trees to be denuded. In
any event, I'll prepare a treatise on the syncronous detector
and launch it post haste...
 
Dr. Strangelove
 
On Tue, 17 Sep 2002 20:43:20 EDT ChrisAtUpw@....... writes:
      But are they=20 genetically modified peanuts?=20

      Regards,=20

      Chris Chapman
=20
Subject: Re: "EPICS" seismo suggestion From: meredithlamb meredithlamb@............. Date: Tue, 17 Sep 2002 22:24:52 -0600 Hi Charles and all, Actually the A3515 Hall sensor, exhibits no gauss or magnetic attraction (with no power on) that I could see either with a strong magnet or a gaussmeter set on its most sensitive scale here. However, some other Hall brand varieties do, as do probably a heavy majority of other use, IC's....especially their tinned iron leads. I've no idea of what a Hall with "power on" could significant influence; but I'd guess its very minor. "Charles R. Patton" wrote: > Aa a sensor solution for the SG seimo, it was proposed to use "…a $1.83 > A3515LUA sensor…" > > So this brings up this thought: Most standard IC frames are magnetic - > consisting of a Kovar frame. And magnetic sensors in particular are > often constructed with "magnetic concentrators" to focus magnetic flux > on to the sensitive area of the chip. Both make the chip physically > attracted to ambient fields. If the chip is not mounted on the SG arm, > then the magnets must be, which would be even worse about ambient > sensitivity. So if one goes for the higher sensitivity of the SG, > doesn't this create problems in terms of an actual physical sensitivity > to the surrounding changing magnetic fields? The Hall would have to be mounted on the boom/mass "normally" of course. It would help to have some Hall shielding (mainly for immediate area "noise") in any S-G with a Hall sensor yes....but I don't think its absolutely essential even there. Years ago, Robert showed me the results of shielding versus no shielding with a small old oscilloscope shield tube....it cut the noise about in half. > I'm thinking back to some > experiments that Roger Baker did on magnetometers in which his > magnetometer is actually a magnet on a torsion balance. He said he > could detect a small magnet many feet away and I know he could sense > geomagnetic changes. It would seem to me that would turn the SG seismo > into a geomagnetic field detector. Roger's detectors were based on > photodetectors and LED or Laser LED sources. Yes, having a suspended magnet mass does react to external magnetic changes....even solar origin flares which can make for magnetic pole/s or earth area variations. I have a separate such instrument of this nature (diamagnetically levitated magnet)....its better for some stronger solar field changes detection...or passing buses/trucks (ha) than the occasional seismic results I'am sure. I guess you could also call it a "metal" detector of sorts (ha). It can be interesting in itself, but one really needs a remote vault...and not in the city as I am located. > I think I'd vote for the original SG variable capacitance detector. > Today you can buy ICs which do all the detection. For one source see > "Universal Capacitive ReadoutTM IC (MS3110)" at: > http://www.microsensors.com/products.html > I don't know how much it costs, but in volume this can't be that > expensive. I also know there is at least a couple of European companies > that makes a similar IC. > > Just some idle musings. Of course, the old coil and magnet sensor approach is the ultimate in simplicity forever it seems......but even there, finding/making or buying a "very good" sensitive coil is the hardest part I suggest. Have to go along with the dual magnet (4 pole) approach that Chris noted also, it seems to increase the coil sensitivity some rough ~ 2 times over that of a single magnet. Adding another attracting 4 pole magnet on the side of the coil (via a normal garden gate seismo), raises the sensitivity higher to about 4-6 times of a single magnet. Such magnets also seem to do well with eddy current damping schemes also. Of course the best coil magnet scheme is with a "speaker" type setup, but for most amateurs, its really tough to do this. Don't know "absolutely" for sure, but I think its hard to beat a Hall setup for being about the cheapest "general", and reliable seismo one could have with all cost aspects considered. Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: "EPICS" seismo suggestion From: Thomas W Leiper twleiper@........ Date: Wed, 18 Sep 2002 00:32:34 -0400 On Tue, 17 Sep 2002 18:38:33 -0600 John & Jan writes: > Hi Tom, > > I'll bite. How is it done? Some time ago I was pondering weak and weary over many a bit of forgotten lore, when I nodded, nearly napping, suddenly there came a tapping, a rapping upon my cranial door. 'Twas only this, and nothing more: I always liked the sensor illustrated in some old Scientific American article (forgotten lore), but felt that using the plates as antennas rather than capacitors was a drawback for too many reasons to put forth here. In any event, the force balance approach recovers many of the potential drawbacks because it (ideally) minimizes excursions so that reasonable linearity can be retained in an inverse-square environment, and the acceleration data is easily integrated to displacement. But it occured to me that if one were to use the plates as capacitors in a pair of tuned circuits rather than as antennas, it would be a simple matter to "lock" these two tank circuits in phase to a very high degree of precision using a couple of counters (just like a freq counter) and apply any offset into a force feedback loop. One could, of course use moving cores in inductors as well, and that was what really got me thinking. If you refer to my modest little arcticle that was posted on the PSN web site a couple years ago, (Nice little seismograph for children) you will note that I used a "solenoid" type magnet and coil design that worked quite well for several years. But the "child" is now a hopeless Internet IM'er beyond salvage, so the seismometer was once again available for malevolent modification. The first experiment involved hoisting it through the open roof of my laboratory during a thunderstorm while Jacob's ladders snapped away next to the bubbling flasks...however the sensitivity seemed a bit reduced when thus suspended. Next, I played around with an SCR exciter and some capacitors and found the coil could be resonant at around 17 Khz with the magnet core half inserted. I then threw together a simple "Twin Tee" oscillator and observed the freqency excursions with my frequency counter and determined the sensitivity to be useful. Next, I made a crystal controlled "divide by N" frequency standard and tuned the detector to match, and added a buffer/limiter to the detector oscillator to convert the signal to a TTL square wave. I also capacitively "decoupled" the detector tank circuit. Finally I fed both signals to a pair of Max/Min 10 bit counters to race each other to the finish. Now, how it operated was thus. When both counters are at maximum they are both reset. Whichever counter reaches maximum first applies a voltage (integrated) opposite that of the other counter to a current amplifier that applies DC to the coil to restore equilibrium. That same DC was, of course used as acceleration data and integrated in my little adding-machine paper recorder. That original experiment breadboard is currently hacked up in preparation for phase two, which is to use two coils and an iron bar with two oscillators, thus avoiding the fixed reference and allowing all temperature effects to be nulled out, as well as the precision tuning required to synchronize with the crystal standard. Depending upon how far you want to divide your oscillators down, you can also adjust the freqency response and "sampling" rate to an incredible degree while achieving displacement sensitivity that is difficult to calculate. I, for one, have never been one to waste time with theoretical performance and instead simply like to see how the traces compare...and these have been at least as good as any I have made previously, with the added benefit of not having to constantly adjust the stupid thing other than mechanical leveling for zero offset current from time to time. Even so, "steady state" offset is essentially DC and is filtered out and not a problem with my recorder, so it is only the non-complementary response to larger excursions that is noticed in the traces when the seismometer is tilted too much. I guess I'll crawl back in my bunker for now and keep finishing off my remaining Y2K supplies... Tom __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: "EPICS" seismo suggestion From: ChrisAtUpw@....... Date: Wed, 18 Sep 2002 22:20:06 EDT In a message dated 18/09/02, twleiper@........ writes: > But it occured to me that if one were to use the plates as capacitors in a > pair of tuned circuits rather than as antennas, it would be a simple matter > to "lock" these > two tank circuits in phase to a very high degree of precision using a > couple of counters (just like a freq counter) and apply any offset into a > force feedback > The capacitor plates have an inverse separation capacity relationship. Depends whether you want to compare frequency or period. Using moving cores in inductors might give a more linear relationship and allow larger movements of the pendulum. > That original experiment breadboard is currently hacked up in preparation > for phase two, which is to use two coils and an iron bar with two > oscillators, thus avoiding the fixed reference and allowing all temperature > effects to be nulled out, as well as the precision tuning required to > synchronize with the crystal standard. Depending upon how far you want to > divide your oscillators down, you can also adjust the freqency response and > "sampling" rate to an incredible degree while achieving displacement > sensitivity that is difficult to calculate. You could cut a ferrite rod in half and use the halves to tune two coils. You might have to provide screening to prevent the oscillators from locking. You might put a flat ferrite plate on the pendulum in between two C ferrite transformer cores. You can buy coil formers with two equal sections for some core sizes. A CD4046 phase lock loop IC comes complete with two types of precision phase comparitors. This would allow continuous sampling. Another alternative which avoids oscillator lock problems is to use the two coils in a variable reluctance switching oscillator and look for tiny changes in the mark / space ratio. Regards, Chris Chapman In a message dated 18/09/02, twleiper@........ writes:

But it occured to me that if one were to use the plates as capacitors in a pair of tuned circuits rather than as antennas, it would be a simple matter to "lock" these
two tank circuits in phase to a very high degree of precision using a couple of counters (just like a freq counter) and apply any offset into a force feedback
loop. One could, of course use moving cores in inductors as well....


      The capacitor plates have an inverse separation capacity relationship. Depends whether you want to compare frequency or period. Using moving cores in inductors might give a more linear relationship and allow larger movements of the pendulum.

That original experiment breadboard is currently hacked up in preparation for phase two, which is to use two coils and an iron bar with two oscillators, thus avoiding the fixed reference and allowing all temperature effects to be nulled out, as well as the precision tuning required to synchronize with the crystal standard. Depending upon how far you want to divide your oscillators down, you can also adjust the freqency response and "sampling" rate to an incredible degree while achieving displacement sensitivity that is difficult to calculate.


      You could cut a ferrite rod in half and use the halves to tune two coils. You might have to provide screening to prevent the oscillators from locking.

      You might put a flat ferrite plate on the pendulum in between two C ferrite transformer cores. You can buy coil formers with two equal sections for some core sizes.

      A CD4046 phase lock loop IC comes complete with two types of precision phase comparitors. This would allow continuous sampling.

      Another alternative which avoids oscillator lock problems is to use the two coils in a variable reluctance switching oscillator and look for tiny changes in the mark / space ratio.

      Regards,

      Chris Chapman   
Subject: Re: "EPICS" seismo suggestion From: Thomas W Leiper twleiper@........ Date: Thu, 19 Sep 2002 00:39:45 -0400 On Wed, 18 Sep 2002 22:20:06 EDT ChrisAtUpw@....... writes: The capacitor plates have an inverse separation capacity relationship. Depends whether you want to compare frequency or period. Using moving cores in inductors might give a more linear relationship and allow larger movements of the pendulum. That is why I decided on moveable cores, although with force-feedback the actual displacement should be minimal and the inverse relationship would only tend to increase sensitivity anyway. So capacitive tuning would probably work as well. The main reason I wanted to try cores was that I thought using the same coil for detection and feedback was neat... You could cut a ferrite rod in half and use the halves to tune two coils. You might have to provide screening to prevent the oscillators from locking. You might put a flat ferrite plate on the pendulum in between two C ferrite transformer cores. You can buy coil formers with two equal sections for some core sizes. I suspect there may be a lot of experimentation here, including separating two iron core sections with a plate of MU, which will be the first experiment if I find too much coupling at the outset. A CD4046 phase lock loop IC comes complete with two types of precision phase comparitors. This would allow continuous sampling. I considered that type of route, but I was concerned about general free-running oscillator stability and felt that one way or the other I would need to average out their rate through longer sampling periods. I would either have to filter the CD4046 output or simply go the counter route, and the junk box ruled the day. Since I am in CT, long period is what I look for, and by simply choosing the bits on the counters I can have sample rates from 8 Hz on up. I think I settled on about 30 Hz which was then integrated in the pen recorder with nice smooth results. Another alternative which avoids oscillator lock problems is to use the two coils in a variable reluctance switching oscillator and look for tiny changes in the mark / space ratio. Actually, I have pondered taking that a step further to see whether the PWM effect would actually provide the centering force at the same time if the oscillator current was sufficient...that would be the ultimate. Anyway, it's a lot of fun trying to reinvent the wheel. I suppose I'll eventually try a beam of light on photographic paper wrapped around a drum and come full circle. Tom
On Wed, 18 Sep 2002 22:20:06 EDT ChrisAtUpw@....... writes:
      The capacitor plates have an= =20 inverse separation capacity relationship. Depends whether you want to = compare=20 frequency or period. Using moving cores in inductors might give a more = linear=20 relationship and allow larger movements of the pendulum.=20
That is why I decided on = moveable cores,=20 although with force-feedback the actual displacement should be minimal = and the=20 inverse relationship would only tend to increase sensitivity anyway. So=20 capacitive tuning would probably work as well. The main reason I wanted = to try=20 cores was that I thought using the same coil for detection and feedback = was=20 neat...


      You could cut a = ferrite=20 rod in half and use the halves to tune two coils. You might have to = provide=20 screening to prevent the oscillators from locking. You might put a = flat=20 ferrite plate on the pendulum in between two C ferrite transformer cores.= You=20 can buy coil formers with two equal sections for some core=20 sizes. 
I suspect there may be a lot of experimentation = here,=20 including separating two iron core sections with a plate of MU, = which=20 will be the first experiment if I find too much coupling at the=20 outset.

      A CD4046 phase lock loop IC = comes=20 complete with two types of precision phase comparitors. This would allow= =20 continuous sampling.
 
I considered that type of route, but I was concerned about = general=20 free-running oscillator stability and felt that one way or the other I = would=20 need to average out their rate through longer sampling periods. I would = either=20 have to filter the CD4046 output or simply go the counter route, and the = junk=20 box ruled the day. Since I am in CT, long period is what I look for,=20 and by simply choosing the bits on the counters I can have sample = rates=20 from 8 Hz on up. I think I settled on about 30 Hz which was then=20 integrated in the pen recorder with nice smooth=20 results.

      Another = alternative=20 which avoids oscillator lock problems is to use the two coils in a = variable=20 reluctance switching oscillator and look for tiny changes in the mark / = space=20 ratio.
 
Actually, I have pondered taking that a step further to see= =20 whether the PWM effect would actually provide the centering force at the = same=20 time if the oscillator current was sufficient...that would be the = ultimate.=20 Anyway, it's a lot of fun trying to reinvent the wheel. I suppose I'll=20 eventually try a beam of light on photographic paper wrapped around a = drum and=20 come full circle.
 
Tom  
 
Subject: Shackleford-Gundersen design questions From: R&L Thompson rlthompson@................. Date: Thu, 19 Sep 2002 17:39:19 -0230 Greetings, I'm back on the list, I don't remember when I went off the list, but it had been such a difficult year for workload that I hadn't though about missing mail. Hopefully, I'll find a little more time to experiment this year. My current project is based on the Shackleford-Gundersen design, and I have a few questions about the design. I'd like some help with the following questions: - what is a practical pendulum length - what way would the mass of the pendulum affect performance. I'm assuming that there is some relationship between the pendulum mass and the amount of force feedback, is there a rule of thumb? (I'm not found of doing the math). Hopefully, the feedback loop gain adjustment is simply a matter of setting the gain just to the point that oscillation is induced, and then backing it off, will that work? Thanks, Ron T. -- R & L Thompson, Gander, Newfoundland, Canada, rlthompson@................. , http://home.thezone.net/~rlthomps/ "Who are these that fly as a cloud, and as the doves to their window?" Is 60:8 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Shackleford-Gundersen design questions From: ChrisAtUpw@....... Date: Thu, 19 Sep 2002 23:47:53 EDT In a message dated 19/09/02, rlthompson@................. writes: > My current project is based on the Shackleford-Gundersen design, and I have > a few questions about the design. > > I'd like some help with the following questions: > - what is a practical pendulum length About 12" will give a 1 sec pendulum. Anything bigger tends to get unwieldy, difficult to mount and use. A 2 sec pendulum is about 39" long. K& S Metals sell various tube in 1' lengths at model making shops. > - what way would the mass of the pendulum affect performance. > 1 oz is the ~real minimum from noise considerations. ~3oz total is more usual. I would suggest making the magnet part of the bob mass, rather then putting it part way up the pendulum. This discourages flexing oscillations of the pendulum and marginally increases the period. > 'm assuming that there is some relationship between the pendulum mass and > the amount of force feedback, is there a rule of thumb? (I'm not found of > doing the math). Hopefully, the feedback loop gain adjustment is simply a > matter of setting the gain just to the point that oscillation is induced, > and then backing it off, will that work? Hi Ron, There is a large download about the SG from Larry on the PSN Website which may be helpful. Also look at http://www.iinet.com.au/~ajbv/index.html and http://pages.prodigy.net/fxc/ To set the damping, you reduce the damping control, displace the pendulum and then release it. You will probably see several oscillations. If it oscillates continually, reverse the coil connections. Increase the damping and repeat the performance until the trace just drops quickly to near zero, but without oscillating or actually crossing the zero line. It is then critically damped. Regards, Chris Chapman In a message dated 19/09/02, rlthompson@................. writes:

My current project is based on the Shackleford-Gundersen design, and I have
a few questions about the design.

    I'd like some help with the following questions:
- what is a practical pendulum length


      About 12" will give a 1 sec pendulum. Anything bigger tends to get unwieldy,  difficult to mount and use. A 2 sec pendulum is about 39" long. K&S Metals sell various tube in 1' lengths at model making shops.

- what way would the mass of the pendulum affect performance.

      1 oz is the ~real minimum from noise considerations. ~3oz total is more usual. I would suggest making the magnet part of the bob mass, rather then putting it part way up the pendulum. This discourages flexing oscillations of the pendulum and marginally increases the period.

I
'm assuming that there is some relationship between the pendulum mass and the amount of force feedback, is there a rule of thumb?  (I'm not found of
doing the math).  Hopefully, the feedback loop gain adjustment is simply a matter of setting the gain just to the point that oscillation is induced, and then backing it off, will that work?


Hi Ron,

      There is a large download about the SG from Larry on the PSN Website which may be helpful. Also look at http://www.iinet.com.au/~ajbv/index.html and http://pages.prodigy.net/fxc/

      To set the damping, you reduce the damping control, displace the pendulum and then release it. You will probably see several oscillations. If it oscillates continually, reverse the coil connections. Increase the damping and repeat the performance until the trace just drops quickly to near zero, but without oscillating or actually crossing the zero line. It is then critically damped.  

      Regards,

      Chris Chapman
Subject: Re: "EPICS" seismo suggestion - capacitance sensors (long) From: "Charles R. Patton" charles.r.patton@........ Date: Thu, 19 Sep 2002 20:47:50 -0700 Chris wrote, "There is NO PROBLEM in this case. Didn't you check the data sheet?" = I have to admit I was trying to take the lazy way out and just ask the question and so I didn't check the spec sheet. I went back and checked out the data sheet for the 3515 and 3516, (27501.10B) and did not see any statements about magnetic or non-magnetic leads - so where does that information appear? In any case, I decided to take on a longer discussion of why I made some of the statements I did. That discussion follows answers to the other question, "What other companies are producing devices similar to the MS3110, please?" = Analog Microelectronics GmbH in Mainz, Germany, has developed a family of analog ASICs, the CAV404, CAV 414 and CAV424. Downloadable spec sheets at: http://www.servoflo.com/analog/data_ho.htm And two articles in Sensors magazine on these ICs. = http://www.sensorsmag.com/articles/0201/88/main.shtml http://www.sensorsmag.com/articles/0402/capacitive/main.shtml I seem to remember that SensNor had one also, but all I could find was: http://www.isit.fhg.de/ which seems to be a custom silicon design house. So make that one other company making capacitive sense ICs for sale on the open market. Some companies have a captive design, for instance, SETRA company makes their own sensor IC, but does not sell it alone, only in their instrumentation products. = So on to the theory. The "New Manual of Seismological Observatory Practice" which covers many topics is at: http://www.seismo.com/msop/nmsop/nmsop.html and discusses many areas of seismometer construction, but in particular the noise floor discussion at: http://www.geophys.uni-stuttgart.de/seismometry/man_html/node28.html and in a discussion on electronic displacement sensors the statement, "Their sensitivity is limited by the ratio between the electronic noise of the demodulator and the electrical field strength; it can be a hundred times better than that of the inductive type. The comprehensive paper by [Jones & Richards1973] on the design of capacitive transducers still represents the state of the art in all essential aspects." is at: http://www.geophys.uni-stuttgart.de/seismometry/man_html/node21.html = Part of the reason a capacitive, or even an inductive sensor, can surpass the Hall effect or LED shutter types is that at the conversion point from a mechanical quantity to an electrical one, there is no noise in the capacitive sensor because it is reactive. A bit of explanation. = There can be several noise sources in a sensor application such as a seismometer. External, such as the one discussed by Sean-Thomas (in the email mentioned below) set one limit. If your electronics were perfect, you can't do any better than your external noise floor. But many times there are additional local sources, which can amount to traffic in the street, trees waving in the breeze, etc. Again these can become the noise floor. But next comes the internally generated noise sources. = The first one is thermal. The arm mass of your seismometer has a temperature and is "vibrating". In addition the air around that mass has Brownian motion and can push on the mass generating noise. This source is problem for miniature sensors such as the Analog Devices MEMs types. Barometric pressure changes "float" the mass which can translate into movement, especially on vertical seismometers. Next comes the electronic noise -- the heart of the discussion that prompts this reply. A non-reactive (resistive) sensor such as a Hall effect sensor or photosensor vs a reactive sensor such as capacitive or inductive sensor suffer from at least two major noise sources, thermal and current noise. These are physical, inherent properties. The thermal noise is proportional to the square root of the product of the resistance, temperature and BW. Amounting to 1.29 nV for 100 ohms, 1 Hz BW, and 295 degrees K. = Current noise is proportional to current and inversely proportional to the frequency of measurement. I.e., it goes up as the frequency goes down and is somewhat dependent on the construction/material of the resistance. = So glancing at the A3515LUA, we find that this floor is 400 uV for a 10 to 10KHz BW in a +/- 2V range. This limits your total range to 10,000 to 1, or about 80 dB. Capacitive and inductive displacement sensors do not have to have either of these noise sources since they are essentially reactive, and the A3515LUA noise sources are due to resistance. A more subtle problem is another noise called the 1/f or flicker noise problem in semiconductors. This noise also rises as the frequency goes down. So the numbers for the A3515LUA will almost surely get worse as we go down in frequency for a seismometer. In particular, 10 Hz is high, when we want to look at tele-seismic events, which is exactly where we need good low noise performance. = One way around 1/f noise is the carrier amplifier, i.e., if you put the information on a carrier frequency, amplify this carrier frequency, then demodulate, you step around the 1/f problem. Coincidentally, this is exactly what happens in capacitive and inductive displacement sensors. = A high frequency is impressed across the sensor capacitor (or inductor). This capacitor changes value according to the displacement, yielding (modulating) that high frequency (carrier) which is amplified by a carrier amplifier. The output of that carrier amplifier is then detected at a high level where the 1/f, thermal and current noises are well below the output. So, you'll note that Sean-Thomas used an inductive sensor on his vertical seismometer. That is one route. Another is that you could easily build the design idea "Circuit resolves 0.1-fF change from 100 pF by Derek Redmayne, Linear Technology Corp, Milpitas, CA (from EDN Access Design Ideas1/6/2000)" at: www.e-insite.net/ednmag/index.asp?layout=3Darticle&articleId=3DCA46462&pu= bdate=3D01/06/2000 The major cost of the semis in quantities of one would be about $32, but this includes a 24 bit digitizer sampling at 7.5 samples/second. = Resolving a 0.1 fF change in 100 pF is a 1,000,000 to 1, or 120 dB range. One measure to decide if this is sufficient. Sean-Thomas mentioned in an email post of Nov 15, 2000 to the PSN list that, "The normal background noise for a seismometer like a Lehman are the 6-second microseisms, usually caused by storms off the east coast. Away from the immediate shore (100km) these run 2 to 4 microns peak-to-peak=85" So for= ease of computation, let's set a goal of 1 micron. Therefore the capacitor plates could be set apart by 1e6 * 1micron, or 1 meter and we could still resolve the mechanical background. Practical construction might be to have parallel plates about 10 mm away on each side (~1/2 inch) from a moving plate on a SG pendulum. Then for 100 pf between the plates we need: C =3D 2.249E-13 * Er * sq.in * (N-1) / (in of separation) so rearranging, substituting and solving we get that we need 222 sq.in of area. Not good. but lets reduce the spacing to about 0.05" and we get 22 sq.in or a plate a bit over 4.5" square. This is doable. A variation would be to salvage the parallel plates of a variable tuning capacitor such as in a broadcast receiver. Fully meshed, the large gang was 365 pF. So, mount so the pendulum meshes the group. Now you have perhaps a 1" range with about 300 pF change. = Another solution would be to implement a slightly different circuit such as the one in the SETRA patents: 4,054,833: 5,194,819: and 6,316,948. = Now the amplifier can provide gain, and the voltage tracks the ratio of bridge caps, so small capacitance changes generate larger voltages and therefore you could use smaller single plate sensors. An example of this was the design idea "Bridge Measures Small Capacitance" by Jeff Witt, Linear Technology Corp, in Electronic Design, Nov. 4, 1996, pg. 110. This circuit seemed to be similar to the SETRA circuits and allow gain. Unfortunately, it does not seem to be available on the web or on Linear Technology's site, even though it was submitted by one of their employees and again used the LTC1043. This final circuit is probably the best compromise of the lot. Take it and add the 24 bit A/D, LTC2400, and you have a powerful combination for low cost. Since the initial output is analog, you have a node that can be fed back to the force coil on the SG and at the same time you get a simple digital stream to feed your computer. = If there's enough interest, I'll scan and make a PDF file and either direct email it, or maybe Larry can warehouse it. Anyway,enough, just some more food for thought. I hope this was clearer, but I often jump over the details from impatience. Oh, yes, an excellent reference for capacitance sensor design: "Capacitive Sensors, Design and Applications," by Larry K. Baxter, IEEE Press. Regards, Charles R. Patton __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Shackleford-Gundersen design questions From: R&L Thompson rlthompson@................. Date: Fri, 20 Sep 2002 07:39:28 -0230 Thanks Chris,

    I'm in the ball park then I figure.  My pendulum length will be about 12 inchs.  Yesterday I made the weight for it, a piece of brass round stock turned in the lathe at work.  It weighs in closer to 6 ounces though.  I'd wanted to have the pendulum assembly as completely free of magnetic material as possible so I'd opted for putting the feedback coil on the pendulum and the magnet mounted to the frame, with, as you've suggested, all the weight and force from the feed back coil located close together near the bottom of the pendulum.

    Nice to be back on the list.

            Ron T.
 

ChrisAtUpw@....... wrote:

In a message dated 19/09/02, rlthompson@................. writes:
 
My current project is based on the Shackleford-Gundersen design, and I have
a few questions about the design.

    I'd like some help with the following questions:
- what is a practical pendulum length

      About 12" will give a 1 sec pendulum. Anything bigger tends to get unwieldy,  difficult to mount and use. A 2 sec pendulum is about 39" long. K&S Metals sell various tube in 1' lengths at model making shops.
 

- what way would the mass of the pendulum affect performance.


      1 oz is the ~real minimum from noise considerations. ~3oz total is more usual. I would suggest making the magnet part of the bob mass, rather then putting it part way up the pendulum. This discourages flexing oscillations of the pendulum and marginally increases the period.

I

'm assuming that there is some relationship between the pendulum mass and the amount of force feedback, is there a rule of thumb?  (I'm not found of
doing the math).  Hopefully, the feedback loop gain adjustment is simply a matter of setting the gain just to the point that oscillation is induced, and then backing it off, will that work?

Hi Ron,

      There is a large download about the SG from Larry on the PSN Website which may be helpful. Also look at http://www.iinet.com.au/~ajbv/index.html and http://pages.prodigy.net/fxc/

      To set the damping, you reduce the damping control, displace the pendulum and then release it. You will probably see several oscillations. If it oscillates continually, reverse the coil connections. Increase the damping and repeat the performance until the trace just drops quickly to near zero, but without oscillating or actually crossing the zero line. It is then critically damped.

      Regards,

      Chris Chapman

--
R & L Thompson,
Gander, Newfoundland, Canada,
rlthompson@................. , http://home.thezone.net/~rlthomps/
"Who are these that fly as a cloud, and as the doves to their window?" Is 60:8
  Subject: Local help From: Ed Ianni eianni2@........... Date: Fri, 20 Sep 2002 21:05:39 -0400 Hi All; I am relatively new to seismology but I find it fascinating. I have recently built a Lehman seismograph and purchased a Windaq "starter kit" and I am now trying to famillarize myself with some of the "basics". I was wondering if there is anyone in the south New Jersey or Philadelphia area who also is into seismology and who may give me a little more "hands on" experience when I need it. Thank you all very much. Sincerely, Ed.

Hi All;
 
    I am relatively new to seismology but I find it fascinating. I have recently built a Lehman seismograph and purchased a Windaq "starter kit" and I am now trying to famillarize myself with some of the "basics". I was wondering if there is anyone in the south New Jersey or Philadelphia area who also is into seismology and who may give me a little more "hands on" experience when I need it. Thank you all very much. Sincerely, Ed. 
Subject: RE: Local help From: "Bob Hancock" robert.hancock@........... Date: Fri, 20 Sep 2002 21:16:08 -0400 Hi Ed – You got 4 “seismoholics” in New Jersey, ranging from middle to the northern part of the state. These are probably the 4 closest. You can get details on each of them from the PSN map at. http://seismicnet.com/dave/USA.htm Click on any of the buttons in NJ, or elsewhere, and the data for each person will come up. It looks like two of us have commercial units, and the other two built their own. I am sure that between the four of us we could steer you in some direction (hopefully) where you want to go. Congratulations on building the unit – now all you have to do is wait for the earth to cooperate and its been doing a lot of that lately. Cheers, Bob Hancock -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Ed Ianni Sent: Friday, September 20, 2002 21:06 To: psn-l@.............. Subject: Local help Hi All; I am relatively new to seismology but I find it fascinating. I have recently built a Lehman seismograph and purchased a Windaq "starter kit" and I am now trying to famillarize myself with some of the "basics". I was wondering if there is anyone in the south New Jersey or Philadelphia area who also is into seismology and who may give me a little more "hands on" experience when I need it. Thank you all very much. Sincerely, Ed.

Hi= Ed –

 

Yo= u got 4 “seismoholics” in New Jersey, ranging from middle to the northern part of the = state.  These are probably the 4 = closest.  You can get details on each of = them from the PSN map at.  http://seismicnet.com/dave/US= A.htm   Click on any of the = buttons in NJ, or elsewhere, and the data for each person will come = up.

 

It= looks like two of us have commercial units, and the other two built their = own.  I am sure that between the = four of us we could steer you in some direction (hopefully) where you want to = go.

 

Co= ngratulations on building the unit – now all you have to do is wait for the = earth to cooperate and its been doing a lot of that = lately.

 

Ch= eers,

 

Bo= b Hancock

 

 

 

-----Original Message-----
From: = psn-l-request@.............. [mailto:psn-l-request@...............On Behalf Of Ed Ianni
Sent: Friday, September = 20, 2002 21:06
To: = psn-l@..............
Subject: Local = help

 

Hi = All;<= /p>

 <= /p>

  &nbs= p; I am relatively new to seismology but I find it fascinating. I have = recently built a Lehman seismograph and purchased a Windaq "starter = kit" and I am now trying to famillarize myself with some of the "basics". = I was wondering if there is anyone in the south New = Jersey or Philadelphia area who also is into seismology and who may give me a = little more "hands on" experience when I need it. Thank you all very = much. Sincerely, Ed. 

Subject: New additions From: David A Nelson davenn@............... Date: Sat, 21 Sep 2002 20:58:24 +1000 Greetings all Again its my pleasure to announce some new members to the PSN that have been added to the station location maps and info lists Jim O'Donnell Boulder City Nevada.. Jim... I went through there by bus one nite back in June '99 the bus stopping for a while at one of the casinos to offload passengers b4 continuing on to Vegas and then back to LA. Dave Booth Saugus, California a bit nth of the San Fernando Valley area a "good place" to be when the next blind thrust event happens in the San Gabriel Mts region hahaha :) and finally Boon Herman from Belgium, good to see another European on the list Alterations..... Nicholas Caporossi and George Bush thanks guys for the updates cheers Dave __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: FW: Research Paper... From: "Kareem" kareem@............. Date: Sat, 21 Sep 2002 15:25:00 -0700 Does anyone know of any online sources of detailed information on recent Hayward Fault and/or Rogers Creek Fault research. I need to do a research paper and I chose to discuss the dangers of that fault. Any help would be appreciated. I'm looking for the most recent and significant discoveries. Kareem Message
Does = anyone know of=20 any online sources of detailed information on recent Hayward = Fault and/or Rogers = Creek Fault research. I = need to do=20 a research paper and I chose to discuss the dangers of that fault. Any = help=20 would be appreciated. I'm looking for the most recent and significant=20 discoveries.
 
Kareem
Subject: 1836 Hayward fault quake From: "Kareem" kareem@............. Date: Sat, 21 Sep 2002 18:15:55 -0700 It seems that the recent (1999) research on the northern extension of the Hayward Fault indicate that the 1836 event may not have occurred along this section.What's become of this particular quake and where did this it occur? Is it totally being deleted from the Hayward Fault's history. Would the deeper creeping, now known to be occurring along the Northern segment, indicate that strain is not accumulating along that section of the fault? So, my apartment and I will (theoretically) not have to be too concerned. Your thoughts? Kareem Message
It = seems that the=20 recent (1999) research on the northern extension of the Hayward = Fault=20 indicate that the 1836 event may not have occurred along this = section.What's=20 become of this particular quake and where did this it occur? Is it = totally=20 being deleted from the Hayward Fault's history. Would the deeper = creeping, now=20 known to be occurring along the Northern segment, indicate that strain = is not=20 accumulating along that section of the fault?
 
So, my = apartment and=20 I will (theoretically) not have to be too concerned. =
 
Your=20 thoughts?
 
 
 
Kareem
Subject: Re: Research Paper... From: "Connie and Jim Lehman" lehmancj@........... Date: Sun, 22 Sep 2002 19:04:51 -0400 Message ----- Original Message -----=20 From: Kareem=20 To: PSN=20 Sent: Saturday, September 21, 2002 6:25 PM Subject: FW: Research Paper... Does anyone know of any online sources of detailed information on = recent Hayward Fault and/or Rogers Creek Fault research. I need to do a = research paper and I chose to discuss the dangers of that fault. Any = help would be appreciated. I'm looking for the most recent and = significant discoveries. Kareem Kareem--In April of 2001 I attended a meeting of the = SSA--Seismological Society of America--meeting in San Francisco. A = number of papers delt with the Hayward Fault, and associated field trip = took the group on location. I no longer have those field notes, but a = good university library may have the Proceedings of that meeting--or = can procure them on Inter-Library Loan. =20 Best wishes Jim Lehman =20 Message
 
----- Original Message -----
From:=20 Kareem=20
To: PSN
Sent: Saturday, September 21, = 2002 6:25=20 PM
Subject: FW: Research = Paper...

Does = anyone know=20 of any online sources of detailed information on recent Hayward=20 Fault and/or Rogers=20 Creek Fault research. I need to do = a=20 research paper and I chose to discuss the dangers of that fault. Any = help=20 would be appreciated. I'm looking for the most recent and significant=20 discoveries.
 
Kareem
 
        = Kareem--In April of 2001 I attended a = meeting of=20 the SSA--Seismological Society of America--meeting in San = Francisco.  A=20 number of papers delt with the Hayward Fault, and associated field = trip took=20 the group on location.  I no longer have those field notes, but a = good=20 university library  may have the Proceedings of that meeting--or = can=20 procure them on Inter-Library Loan. 
       &nbs= p;            = ;           =20 Best wishes
       &nbs= p;            = ;           =20 Jim Lehman
    =20
Subject: Re: Research Paper... Hayward & Rogers Creek From: ChrisAtUpw@....... Date: Sun, 22 Sep 2002 19:36:45 EDT In a message dated 23/09/02, lehmancj@........... writes: > Does anyone know of any online sources of detailed information on recent > Hi Kareem, It rather depends on what information you need and in what detail. I just typed 'Hayward Fault' into www.google.com and got 10,800 references..... If you allow 5 mins for each and work 16 hr days, you could be finished in just 8 weeks.... There seems to be plenty of information; sorting it may be more of a problem. There are usually 'review papers' from time to time which you should look out for. The emergency services in the area will probably have up to date information and know of most developments and 'forecasts'. Regards, Chris Chapman In a message dated 23/09/02, lehmancj@........... writes:

Does anyone know of any online sources of detailed information on recent Hayward Fault and/or Rogers Creek Fault research.


Hi Kareem,

      It rather depends on what information you need and in what detail.
      I just typed 'Hayward Fault' into www.google.com and got 10,800 references..... If you allow 5 mins for each and work 16 hr days, you could be finished in just 8 weeks....
      There seems to be plenty of information; sorting it may be more of a problem. There are usually 'review papers' from time to time which you should look out for. The emergency services in the area will probably have up to date information and know of most developments and 'forecasts'.

      Regards,

      Chris Chapman
Subject: John Hernlund's Address From: John & Jan Lahr johnjan@........ Date: Sun, 22 Sep 2002 17:39:33 -0600 Does anybody have John Hernlund's current E-mail address? Recipient: Reason: 5.1.1 unknown or illegal user: hernlund@....... Thanks, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: John Hernlund's Address From: ChrisAtUpw@....... Date: Sun, 22 Sep 2002 19:51:17 EDT In a message dated 23/09/02, johnjan@........ writes: > Does anybody have John Hernlund's current E-mail address? > Hi John, My EMail records give Date: 02/07/02 From: hernlund@............ (John Hernlund) Hope that this is of help. Regards, Chris Chapman In a message dated 23/09/02, johnjan@........ writes:

Does anybody have John Hernlund's current E-mail address?

Hi John,

      My EMail records give Date: 02/07/02 From: hernlund@............ (John Hernlund)

      Hope that this is of help.

      Regards,

      Chris Chapman
Subject: Tremour From: "S Shufflebotham" Cellectronic@.............. Date: Mon, 23 Sep 2002 01:13:41 +0100 Hi All,, I was just awoke by a tremour , and my equipment started the = recording at 00:56:32 on 29,09,02 more details will be available from = me at a more sociable hour, we are based in South Shropshire,UK. Regards to you all=20 Steve
Hi All,, I was just awoke by a tremour , and my = equipment=20 started the recording at 00:56:32  on 29,09,02 more details will be = available from me at a more sociable hour, we are based in South = Shropshire,UK.
Regards to you all
Steve
Subject: Re: Using Wood on Shackleford-Gundersen detector From: R&L Thompson rlthompson@................. Date: Sun, 22 Sep 2002 21:55:05 -0230 Hi Nick,

    I didn't see any problem with using wood, as long as it didn't warp.  It's all older dry wood, and been clear coated.

    There is a lot that I'm doing different in this design, including the transmitter / receiver design, detector (which I plan to build myself), and how the force feedback works.  I haven't done anything more than rough sketches, which change as I find out what material I can scrouge up to build it.  When its finished, and if it works well, it will have the Shackleford-Gundersen form, but will have some significant differences with respect to how it works.

    If we could send image files to the list, I'd post a few rough sketches for comments.

    Thanks for your interest.

            Ron T.

Nick Caporossi wrote:

Hi Ron: Using Stainless steel, it's a very good idea.Have you ask the PSN group about using wood for parts in sensor? Should be interesting what some comments would be. Will you be building the Electronics for the detector your self. Do you have plans for the Receiver and Transmitter ( Not sure if that is the correct name for those parts.) Nick
----- Original Message -----
Sent: Saturday, September 21, 2002 6:46 PM
Subject: Re: Shackleford-Gundersen design questions
 Hi Nick,

    nice job on your detector.  I've been making mine out of wood, it is only my first attempt at building one.  For the hinge at the top, I plan to use stainless steel foil that was originally used as the recording medium (analog form, the data was scribed onto the foil).   I'm not sure what the thickness is, but a 200 ft spool of it is less than 3 inches in diameter.
 
 

--
R & L Thompson,
Gander, Newfoundland, Canada,
rlthompson@................. , http://home.thezone.net/~rlthomps/
"Who are these that fly as a cloud, and as the doves to their window?" Is 60:8
  Subject: Re: Tremour-M4.5 From: Seisguy@....... Date: Sun, 22 Sep 2002 20:19:28 EDT Just listed from Red Puma: 22Sep2002 23:53:25.0 52.1N 1.5W 10 ML=4.5 A*LED UNITED KINGDOM Regards, Mike O'Bleness Palm Springs, CA Just listed from Red Puma:

22Sep2002 23:53:25.0 52.1N   1.5W 10 ML=4.5 A*LED UNITED KINGDOM           

Regards,

Mike O'Bleness
Palm Springs, CA
Subject: Re: John Hernlund's Address From: John & Jan Lahr johnjan@........ Date: Sun, 22 Sep 2002 20:30:54 -0600 THANKS! John At 07:51 PM 9/22/2002 -0400, you wrote: >In a message dated 23/09/02, johnjan@........ writes: > >>Does anybody have John Hernlund's current E-mail address? > >Hi John, > > My EMail records give Date: 02/07/02 From: hernlund@............ > (John Hernlund) > > Hope that this is of help. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: A simpler Shackleford-Gundersen frame From: meredithlamb meredithlamb@............. Date: Sun, 22 Sep 2002 21:07:22 -0600 Hi all, For a "down and dirty & cheap S-G frame": A concrete paver and or about 5 ceramic bricks could also be used as a S-G "frame" (one could use more bricks laid flat of course). The concrete paver could be the base. Two pairs of bricks end on end atop the paver, with the fifth brick being the crossover piece. Most (U.S.) bricks have 3 holes in them, likely two of the outside holes downward could suspend the S-G hinges/boom/mass. Probably a concrete drill and using a old threaded tap size, could give the 3 "setcrews" action for adjustments....but even here, simple wedges could be subsituted. Epoxy or even cement could be used for glueing the thing together. One might not even need a "boom", if another brick is used as the "mass".....as two thin spaced magnet wires are likely strong enough to support it. One could adjust the wire lengths for the period somewhat. I use 0.001" thick by 0.0250 wide by 1.5" length brass strips as the hinges in my S-G's with a ~ 3 pound mass as its needed for the normal period and tilt sensitivity of a Hall sensor....none have broken yet over acouple years or so since installation. Most bricks are electrical insulators and that helps. There is probably some iron oxide in some bricks, but I doubt its sufficient to have much influence over its mass weight inertia versus any introduced magnets. Probably the lighter in color the brick; the less the iron or other magnetic contaminants there is. Yes; one could attach a coil....or other wires for whatever sensor arrangement is desired. What the heck....its going to be set up in a vault or basement anyway and theres NO known "spiffy" seismo fashion appearance magazine reporters around (ha) and this possible ultimate in simplicity will get you recording alot faster. One thing for sure, it will be quite sturdy (and heavy) which helps. Damping could be via a oil van/tank or a eddy current damping add-on on the "paver" base itself. The damping aspect maybe the most time consuming aspect overall. Have to admit, I have no such "critter" here though...ha. OK.....you could paint it "professional" white, if its appearance is more "critical".....to your personal ego standards....on the other hand...auto "chrome" paint could somewhat mask the true nature of the "critter"....ha. The primer and paint helps prevent water absorption expansion and contraction problems around the cement joints...apply any paint after a sufficient cementing drying time has expired. Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: A simpler Shackleford-Gundersen frame From: Keith Payea kpayea@........... Date: Sun, 22 Sep 2002 20:59:51 -0700 Hello All: I took the concrete block and epoxy approach when I built my STM-8 vertical. I used two layers of 8 x 16 and 8 x 8 pavers to make a base 8 by 24 inches. The end of the boom is supported on a pair of concrete bricks. This whole thing is held together with construction adhesive. I painted the concrete with a good white sealer/primer to keep moisture out. Other parts are attached by drilling a shallow hole in the concrete and using epoxy to attach a "T" nut to the concrete. Then the part is just bolted down. This machine has been in operation for almost three years with no problems. It is very stable. I too toyed with the idea of building an SG out of concrete parts. My concept was to use a 12" square paver or two for the base, and then stand three 8 x 16 pavers on end so they look like a "U" shape when viewed from above. I never got a chance to try it out. Cheers, Keith Payea ----- Original Message ----- From: "meredithlamb" To: Sent: Sunday, September 22, 2002 8:07 PM Subject: A simpler Shackleford-Gundersen frame > Hi all, > > For a "down and dirty & cheap S-G frame": > > A concrete paver and or about 5 ceramic bricks could also > be used as a S-G "frame" (one could use more bricks laid > flat of course). The concrete paver could be the base. Two > pairs of bricks end on end atop the paver, with the fifth brick > being the crossover piece. Most (U.S.) bricks have 3 holes in > them, likely two of the outside holes downward could suspend > the S-G hinges/boom/mass. Probably a concrete drill > and using a old threaded tap size, could give the 3 "setcrews" > action for adjustments....but even here, simple wedges could > be subsituted. Epoxy or even cement could be used for glueing > the thing together. > > One might not even need a "boom", if another brick is used as > the "mass".....as two thin spaced magnet wires are likely strong > enough to support it. One could adjust the wire lengths for > the period somewhat. I use 0.001" thick by 0.0250 wide by > 1.5" length brass strips as the hinges in my S-G's with a ~ 3 > pound mass as its needed for the normal period and tilt > sensitivity of a Hall sensor....none have broken yet over > acouple years or so since installation. > > Most bricks are electrical insulators and that helps. There > is probably some iron oxide in some bricks, but I doubt its > sufficient to have much influence over its mass weight inertia > versus any introduced magnets. Probably the lighter in color > the brick; the less the iron or other magnetic contaminants > there is. > > Yes; one could attach a coil....or other wires for whatever sensor > arrangement is desired. What the heck....its going to be set up in a > vault or basement anyway and theres NO known "spiffy" seismo > fashion appearance magazine reporters around (ha) and this > possible ultimate in simplicity will get you recording alot faster. > One thing for sure, it will be quite sturdy (and heavy) which > helps. > > Damping could be via a oil van/tank or a eddy current damping > add-on on the "paver" base itself. The damping aspect maybe > the most time consuming aspect overall. > > Have to admit, I have no such "critter" here though...ha. > > OK.....you could paint it "professional" white, if its > appearance is more "critical".....to your personal ego > standards....on the other hand...auto "chrome" paint could > somewhat mask the true nature of the "critter"....ha. The > primer and paint helps prevent water absorption expansion > and contraction problems around the cement joints...apply > any paint after a sufficient cementing drying time has expired. > > Take care, Meredith Lamb > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: A simpler Shackleford-Gundersen frame From: meredithlamb meredithlamb@............. Date: Sun, 22 Sep 2002 23:52:55 -0600 Hi Keith, Hey.....thats great on the stability part....its most useful to know, including the "T" nuts application to such! What brand of construction adhesive did you use? Most glues don't work well with water over time....finding a very good U.S.A., brand is tough it seems. The Permabond F246 variety from the UK seems highly excellent for thin glue gap uses but for thick gaps like concrete....I don't know? Somes "little" stuff like the glue determine success or failure.... Thanks for the informative reply! Meredith Lamb Keith Payea wrote: > Hello All: > > I took the concrete block and epoxy approach when I built my STM-8 vertical. > I used two layers of 8 x 16 and 8 x 8 pavers to make a base 8 by 24 inches. > The end of the boom is supported on a pair of concrete bricks. This whole > thing is held together with construction adhesive. I painted the concrete > with a good white sealer/primer to keep moisture out. Other parts are > attached by drilling a shallow hole in the concrete and using epoxy to > attach a "T" nut to the concrete. Then the part is just bolted down. This > machine has been in operation for almost three years with no problems. It > is very stable. I too toyed with the idea of building an SG out of > concrete parts. My concept was to use a 12" square paver or two for the > base, and then stand three 8 x 16 pavers on end so they look like a "U" > shape when viewed from above. I never got a chance to try it out. > > Cheers, > > Keith Payea __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: United Kingdom From: "Francesco" fra.nuc@........... Date: Mon, 23 Sep 2002 08:20:39 +0200 the European Mediterranean Seismological Center report an ML 4.9 quake = located at 52.7N 2.0W at 23.53.10 Some of our station have registered the event with long period sensor. Regards Francesco Nucera - Italy

the European Mediterranean = Seismological Center=20 report an ML 4.9 quake located at 52.7N  2.0W at = 23.53.10
Some of our station have registered the = event with=20 long period sensor.
 
Regards
 
Francesco Nucera  -=20 Italy
Subject: RE: Research Paper... From: "Kareem" kareem@............. Date: Mon, 23 Sep 2002 07:12:39 -0700 Thanks, I googled the information from the Net. The most recent research seems to be the Working Groups (1999) from the USGS and Roland = B=FCrgmann. Thanks for all of your help.=20 =20 I still would like to hear what others have heard though about the Northern Extension of the Hayward fault in addition to the these other studies. =20 Kareem -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Connie and Jim Lehman Sent: Sunday, September 22, 2002 4:05 PM To: psn-l@.............. Subject: Re: Research Paper... =20 ----- Original Message -----=20 From: Kareem =20 To: PSN =20 Sent: Saturday, September 21, 2002 6:25 PM Subject: FW: Research Paper... Does anyone know of any online sources of detailed information on recent Hayward Fault and/or Rogers Creek Fault research. I need to do a research paper and I chose to discuss the dangers of that fault. Any help would be appreciated. I'm looking for the most recent and significant discoveries. =20 Kareem =20 Kareem--In April of 2001 I attended a meeting of the SSA--Seismological Society of America--meeting in San Francisco. A number of papers delt with the Hayward Fault, and associated field trip took the group on location. I no longer have those field notes, but a good university library may have the Proceedings of that meeting--or can procure them on Inter-Library Loan. =20 Best wishes Jim Lehman =20 Message
Thanks, = I googled=20 the information from the Net. The most recent research seems to be the = Working=20 Groups (1999) from the USGS and Roland B=FCrgmann. Thanks for all of = your help.=20
 
I still = would like to=20 hear what others have heard though about the Northern Extension of the = Hayward=20 fault in addition to the these other studies.
 
Kareem
-----Original Message-----
From:=20 psn-l-request@.............. [mailto:psn-l-request@............... = On=20 Behalf Of Connie and Jim Lehman
Sent: Sunday, September = 22, 2002=20 4:05 PM
To: psn-l@..............
Subject: Re: = Research=20 Paper...

 
----- Original Message -----
From:=20 Kareem=20
To: PSN
Sent: Saturday, September 21, = 2002 6:25=20 PM
Subject: FW: Research = Paper...

Does anyone know=20 of any online sources of detailed information on recent Hayward = Fault and/or Rogers Creek Fault research. I need to = do a=20 research paper and I chose to discuss the dangers of that fault. Any = help=20 would be appreciated. I'm looking for the most recent and = significant=20 discoveries.
 
Kareem
 
        = Kareem--In April of 2001 I attended = a meeting=20 of the SSA--Seismological Society of America--meeting in San=20 Francisco.  A number of papers delt with the Hayward Fault, and = associated field trip took the group on location.  I no longer = have=20 those field notes, but a good university library  may have the=20 Proceedings of that meeting--or can procure them on Inter-Library=20 Loan. 
       &nbs= p;            = ;           =20 Best wishes
       &nbs= p;            = ;           =20 Jim Lehman
    =20
Subject: Local distance From: Ed Ianni eianni2@........... Date: Mon, 23 Sep 2002 10:31:57 -0400 Hi All; If two seismographs are placed at right a angles to each other, what would be the minimum distance apart from each other that they can be placed (from each other), for a rough approximation of an event? Thank you Ed.
Hi All;
    If two seismographs are placed at right a angles to each other, what would be the minimum distance apart from each other that they can be placed (from each other), for a rough approximation of an event? Thank you Ed.  
Subject: Re: "EPICS" seismo suggestion - capacitance sensors (more) From: ChrisAtUpw@....... Date: Wed, 25 Sep 2002 22:27:36 EDT In a message dated 20/09/02, charles.r.patton@........ writes: Hi Charles, Great effort in assembling the very informative EMail! Good info and=20 thought provoking!=20 =20 > Chris wrote, "There is NO PROBLEM in this case. Didn't you check the > data sheet?" =20 > I have to admit I was trying to take the lazy way out and just ask the=20 > question and so I didn't check the spec sheet. I went back and checked ou= t=20 > the data sheet for the 3515 and 3516, (27501.10B) and did not see any=20 > statements about magnetic or non-magnetic leads - so where does that=20 >=20 There is no reference to a flux concentrator since none is used. If=20 one is used, details are given on the data sheet and on the drawings. I have checked the on-line A3515 data sheet and you are perfectly=20 correct that the lead material is not mentioned. My apologies! It was=20 specified in application information relating the A3505. I confirm that the=20 A3515 leads are non magnetic. > "What other companies are producing devices similar to the MS3110, please= ?"=20 > =20 > Analog Microelectronics GmbH in Mainz, Germany, has developed a family > of analog ASICs, the CAV404, CAV 414 and CAV424. Downloadable spec > sheets at: http://www.servoflo.com/analog/data_ho.htm Thanks. Google came up with XEMICS, fairly similar to the MS3110, but= =20 they do quote resolutions, etc. and seem to be clued up on getting high=20 accuracy; see http://www.xemics.com/internet/index2.jsp > So on to the theory. The "New Manual of Seismological Observatory > Practice" which covers many topics is at: > http://www.seismo.com/msop/nmsop/nmsop.html and discusses many areas of=20 > seismometer construction, but in particular the noise floor discussion at: >=20 See also http://www.ifjf.uib.no/seismo/SOFTWARE/OTHER/instrument.pdf 'Instrumentation in Earth Seismology' is a very good account and it is=20 complete, but it is a large file. The Stuttgart files seem to be all divided= =20 into short sections.=20 > And in a discussion on electronic displacement sensors the statement, > "Their sensitivity is limited by the ratio between the electronic noise of= =20 > the demodulator and the electrical field strength; it can be a hundred=20 >=20 However, both capacitative and inductive types can give resolutions o= f=20 less than 1 nano metre, so while I have no doubt that this is correct, it=20 need not effect us. You need a very quiet site indeed to be able to make use= =20 of this sort of resolution.=20 > Part of the reason a capacitive, or even an inductive sensor, can surpass=20 > the Hall effect or LED shutter types is that at the conversion point from=20= a=20 > mechanical quantity to an electrical one, there is no noise in the=20 > capacitive sensor because it is reactive. A bit of explanation.=20 > There can be several noise sources in a sensor application such as a=20 > seismometer. External, such as the one discussed by Sean-Thomas (in the=20 > email mentioned below) set one limit. If your electronics were perfect,=20 > you can't do any better than your external noise floor. But many times=20 > there are additional local sources, which can amount to traffic in the=20 > street, trees waving in the breeze, etc. Again these can become the noise= =20 > floor. > But next comes the internally generated noise sources. The first one i= s=20 > thermal. The arm mass of your seismometer has a temperature and is=20 > "vibrating" with Brownian motion. The air around that mass also has=20 > Brownian motion which can push on the mass generating noise. This source i= s=20 >=20 The Brownian motion of the sensor may require you to use a seismic=20 mass of more than 1 oz using feedback type damping, with typical masses=20 several times this. Systems with passive damping may need to be heavier. The air may also develop motion due to thermal gradients, whichcan be= =20 severe and may be more of a problem with long period / large instruments. Th= e=20 movements may be continuous, only appear every few minutes, intermittently,=20 or when the outside air cools down.=20 =20 > Barometric pressure changes "float" the mass which can translate into=20 > movement, especially on vertical seismometers. =20 This is a major source of noise on verticals which are not in a seale= d=20 container and may include pressure fluctuations due to wind. Next comes the=20 > electronic noise -- the heart of the discussion that prompts this > reply. A non-reactive (resistive) sensor such as a Hall effect sensor or=20 > photosensor vs a reactive sensor such as capacitive or inductive sensor=20 > suffer from at least two major noise sources, thermal and current noise. =20 > These are physical, inherent properties. The thermal noise is proportiona= l=20 > to the square root of the product of the resistance, temperature and BW. =20 > Amounting to 1.29 nV for 100 ohms, 1 Hz BW, and 295 degrees K. =20 > Current noise is proportional to current and inversely proportional to the= =20 > frequency of measurement. I.e., it goes up as the frequency goes down and= =20 >=20 > So glancing at the A3515LUA, we find that this floor is 400 uV for a 10 to= =20 > 10KHz BW in a +/- 2V range. This limits your total range to 10,000 to 1,=20 > or about 80 dB. Capacitive and inductive displacement= =20 > sensors do not have to have either of these noise sources since they are=20 >=20 Perhaps I should have made it clearer that the resolution that I=20 quoted for the A3515 based linear magnetic detector was actually measured an= d=20 was determined for 30 sec periods, peak to peak. The above characteristic=20 agrees with my readings fairly well. The 400 micro V RMS =3D 566 micro V pk=20 (presumably over 1/10 sec), but the bandwidth is only 10 Hz so the rough=20 noise estimate is ~ 18 micro V and this is a 'typical' single deviation valu= e=20 only. You may get about 2 standard deviations over longer periods. After=20 taking into account some increase in low frequency noise levels and adding=20 power supplies, an amplifier and filter, my <100 micro V resolution is not=20 too bad. It can be further reduced if you opt for 3 Hz or less bandwidth. Th= e=20 overall range is ~40,000, which is better than the 14 true bits (16,384 -=20 84dB) you get out of most nominally 16 bit A/D converters. > A more subtle problem is another noise called the 1/f or flicker noise= =20 > problem in semiconductors. This noise also rises as the frequency goes=20 > down. So the numbers for the A3515LUA will almost surely get worse as we=20 > go down in frequency for a seismometer. In particular, 10 Hz is high, whe= n=20 > we want to look at teleseismic events, which is exactly where we need good= =20 >=20 This was why I was so pleased when I learnt about the A3515s! I had=20 been working with A3505s previously and they were significantly noisier at=20 the low frequencies. However, Allegro put a chopper amplifier in the A3515=20 which rejects most 1/f noise and this is exactly what we need for the longer= =20 period seismic observations! They are uniquely well suited to this=20 application. One note: the output impedance of an A3515 is very low and there is=20 some very wide band noise on it. This can be rejected by connecting a 4.7 mH= =20 choke and a 10 nF ceramic capacitor to the output pin. A 100 nF ceramic=20 capacitor should be connected across the supply lines close to the device.=20 =20 > One way around 1/f noise is the carrier amplifier, i.e., if you put th= e=20 > information on a carrier frequency, amplify this carrier frequency, then=20 > demodulate, you step around the 1/f problem. Coincidentally, this is=20 > exactly what happens in capacitative and inductive displacement sensors.=20 > A high frequency is impressed across the sensor capacitor (or inductor). =20 > This capacitor changes value according to the displacement, yielding=20 > (modulating) that high frequency (carrier) which is amplified by a carrier= =20 > amplifier. The output of that carrier amplifier is then detected and=20 > filtered at a high level where the 1/f, thermal and current noises are wel= l=20 > below the output. So, you'll note that Sean-Thomas used an inductive=20 > sensor on his vertical seismometer. That is one route. > Another is that you could easily build the design idea "Circuit resolves > 0.1-fF change from 100 pF by Derek Redmayne, Linear Technology Corp, > Milpitas, CA (from EDN Access Design Ideas1/6/2000)" at: > www.e-insite.net/ednmag/index.asp?layout=3Darticle&articleId=3DCA46462& > pubdate=3D01/06/2000 > The major cost of the semis in quantities of one would be about $32, but=20 > this includes a 24 bit digitizer sampling at 7.5 samples/second.=20 > Resolving a 0.1 fF change in 100 pF is a 1,000,000 to 1, or 120 dB > range. =20 This looks like the most promising candidate for the differential=20 capacity measurements that we need. The gain is only two, but this could=20 easily be increased and two off two pole filters, a high pass filter ~40 sec= =20 and an output amplifier added to give a complete system. If you used a +/- 1= 0=20 mm range for a Lehman, the step size for a 14 bit true A/D would be about 1.= 2=20 microns. To allow for drift you add a high pass filter and then amplify the=20 signal x100, or as convenient. The gives high resolution and is not sensitiv= e=20 to slow drifts. You could add a 'cheap' tuning 10 V movng coil meter to the=20 direct output to read off the position of the arm, to know when it needs=20 re-centering. One measure to decide if this is sufficient. Sean-Thomas=20 > mentioned in an email post of Nov 15, 2000 to the PSN list that, "The norm= al=20 > background noise for a seismometer like a Lehman are the 6-second=20 > microseisms, usually caused by storms off the east coast. Away from the=20 > immediate shore (100km) these run 2 to 4 microns peak-to-peak=E2=80=A6" S= o for=20 > ease of computation, let's set a goal of 1 micron. Therefore the capacito= r=20 > plates could be set apart by 1e6 * 1micron, or 1 meter and we could still=20 > resolve the mechanical background. Practical construction might be to hav= e=20 > parallel plates about 10 mm away on each side (~1/2 inch) from a moving=20 > plate on a SG pendulum. Then for 100 pf between the plates we need: C=20= =3D=20 > 2.249E-13 * Er * sq.in * (N-1) / (in of separation) so rearranging,=20 > substituting and solving we get that we need 222 sq.in > of area. Not good. but lets reduce the spacing to about 0.05" and we get= =20 > 22 sq.in or a plate a bit over 4.5" square. =20 You need to check on air damping for sizeable capacitor plates which=20 move toward or away from each other. This can be a serious limitation and=20 there are 'guideline' estimates.=20 A variation would be to salvage the parallel plates of a variable tuning=20 capacitor such=20 > as in a broadcast receiver. Fully meshed, the large gang was 365 pF. So,= =20 > mount so the pendulum meshes the group. Now you have perhaps a 1" range=20 >=20 Maintaining the alignment could be just a bit difficult with an ex=20 radio variable capacitor and they are of a rather odd shape, designed to giv= e=20 a ~linear wavelength scale. The high voltage transmitter types have larger=20 spacing. It would probably be both easier and more satisfactory to make a=20 variable area plate capacitor out of sheet brass and spacers.=20 Another solution would be to implement a slightly different circuit such=20 > as the one in the SETRA patents: 4,054,833: 5,194,819: and 6,316,948. Now=20 > the amplifier can provide gain, and the voltage tracks the ratio of bridge= =20 > caps, so small capacitance changes generate larger voltages and therefore=20 > you could use smaller single plate sensors. > An example of this was the design idea "Bridge Measures Small Capacitance"= =20 > by Jeff Witt, Linear Technology Corp, in Electronic Design, Nov. 4, 1996,=20 >=20 See http://www.linear.com/pdf/an87.pdf page 87 for this article. This circuit is designed to measure a variable capacity with referenc= e=20 to a fixed capacity using an integrating feedback path. One problem with sei= s=20 sensors is that the variable capacity also varies with temperature, at about= =20 20 ppm / C Deg for Brass. This does not sound a lot, but if the full sensor=20 range was 20 mm, this would represent 0.4 micron / C deg, when we may be=20 interested in quake signals down to 1/40 of this or less. You could, however= ,=20 make a fixed reference capacitor out of the same materials. A differential=20 capacity arrangement only experiences the 20 ppm variation on the difference= ,=20 not on the overall capacity - the zero should be designed to be ~constant=20 with temperature. They are also less sensitive to eccentric movement /=20 wobbles at right angles to the normal movement. The 'professional' type=20 sensor that I looked at was made from silver plated invar. This circuit seemed to be similar to the SETRA circuits and allow gain. =20 > This final circuit is probably the best compromise of the lot. Take it an= d=20 > add the 24 bit A/D, LTC2400, and you have a powerful combination for low=20 > cost. Since the initial output is analog, you have a node that can be fed= =20 > back to the force coil on the SG and at the same time you get a simple=20 >=20 The signals which you wish to resolve and record will be of different= =20 frequency and may be far lower in amplitude than the ocean microseisms -=20 maybe 1% the size. Having to record large 'noise' signals at the same time a= s=20 much smaller quake signals puts definite limits on the signal processing.=20 =20 It is a pity that the LTC2400 is only available in a SOIC miniature=20 package. > Oh, yes, an excellent reference for capacitance sensor design: "Capacitive= =20 >=20 I agree! It is very good and describes a lot of very diverse practica= l=20 applications in detail. ISBN =3D 078035351X. Unfortunately, the paperback=20 edition is $99-95 new, but you might try your library. Regards, Chris Chapman In a message dated 20/09/= 02, charles.r.patton@........ writes:

Hi Charles,

      Great effort in assembling the very= informative EMail! Good info and thought provoking!=20
=20
Chris wrote, "There is NO P= ROBLEM in this case. Didn't you check the
data sheet?"  
I have to admit I was trying to take the lazy way out and just ask the q= uestion and so I didn't check the spec sheet.  I went back and checked=20= out the data sheet for the 3515 and 3516, (27501.10B) and did not see any st= atements about magnetic or non-magnetic leads - so where does that informati= on appear?


      There is no reference to a flux con= centrator since none is used. If one is used, details are given on the data=20= sheet and on the drawings.

      I have checked the on-line A3515 da= ta sheet and you are perfectly correct that the lead material is not mention= ed. My apologies! It was specified in application information relating the A= 3505. I confirm that the A3515 leads are non magnetic.

"What other companies are=20= producing devices similar to the MS3110, please?"   
Analog Microelectronics GmbH in Mainz, Germany, has developed a family
of analog ASICs, the CAV404, CAV 414 and CAV424.  Downloadable spec
sheets at: http://www.servoflo.com/analog/data_ho.htm


      Thanks. Google came up with XEMICS,= fairly similar to the MS3110, but they do quote resolutions, etc. and seem=20= to be clued up on getting high accuracy; see http://www.xemics.com/internet/= index2.jsp

So on to the theory.  = The "New Manual of Seismological Observatory
Practice" which covers many topics is at:
http://www.seismo.com/msop/nmsop/nmsop.html and discusses many areas of=20= seismometer construction, but in particular the noise floor discussion at:
http://www.geophys.uni-stuttgart.de/seismometry/man_html/node28.html

      See also http://www.ifjf.uib.no/sei= smo/SOFTWARE/OTHER/instrument.pdf
'Instrumentation in Earth Seismology' is a very good accou= nt and it is complete, but it is a large file. The Stuttgart files seem to b= e all divided into short sections.=20

And in a discussion on elec= tronic displacement sensors the statement,
"Their sensitivity is limited by the ratio between the electronic noise=20= of the demodulator and the electrical field strength; it can be a hundred ti= mes better than that of the inductive type.


      However, both capacitative and indu= ctive types can give resolutions of less than 1 nano metre, so while I have=20= no doubt that this is correct, it need not effect us. You need a very=20= quiet site indeed to be able to make use of this sort of resolution.= =20

Part of the reason a capaci= tive, or even an inductive sensor, can surpass the Hall effect or LED shutte= r types is that at the conversion point from a mechanical quantity to an ele= ctrical one, there is no noise in the capacitive sensor because it is reacti= ve.  A bit of explanation.=20
   There can be several noise sources in a sensor applic= ation such as a seismometer.  External, such as the one discussed by Se= an-Thomas (in the email mentioned below) set one limit.  If your electr= onics were perfect, you can't do any better than your external noise floor.=20=  But many times there are additional local sources, which can amount to= traffic in the street, trees waving in the breeze, etc.  Again these c= an become the noise floor.
   But next comes the internally generated noise sources= .. The first one is thermal.  The arm mass of your seismometer has a tem= perature and is "vibrating" with Brownian motion. The air around that mass a= lso has Brownian motion which can push on the mass generating noise. This so= urce is problem for miniature sensors such as the Analog Devices MEMs types.=


      The Brownian motion of the sensor m= ay require you to use a seismic mass of more than 1 oz using feedback type d= amping, with typical masses several times this. Systems with passive damping= may need to be heavier.

      The air may also develop motion due= to thermal gradients, whichcan be severe and may be more of a problem with=20= long period / large instruments. The movements may be continuous, only appea= r every few minutes, intermittently, or when the outside air cools down.=20
=20
  Barometric pre= ssure changes "float" the mass which can translate into movement, especially= on vertical seismometers.  


      This is a major source of noise on=20= verticals which are not in a sealed container and may include pressure fluct= uations due to wind.

Next comes the=20
electronic noise -- the hea= rt of the discussion that prompts this
reply.  A non-reactive (resistive) sensor such as a Hall effect sen= sor or photosensor vs a reactive sensor such as capacitive or inductive sens= or suffer from at least two major noise sources, thermal and current noise.=20=  These are physical, inherent properties.  The thermal noise is pr= oportional to the square root of the product of the resistance, temperature=20= and BW.  Amounting to 1.29 nV for 100 ohms, 1 Hz BW, and 295 degrees K.=  
Current noise is proportional to current and inversely proportional to t= he frequency of measurement.  I.e., it goes up as the frequency goes do= wn and is somewhat dependent on the construction/material of the resistance.=



So glancing at the A3515LUA= , we find that this floor is 400 uV for a 10 to 10KHz BW in a +/- 2V range.=20=  This limits your total range to 10,000 to 1, or about 80 dB.  &nb= sp;            &= nbsp;      Capacitive and inductive displaceme= nt sensors do not have to have either of these noise sources since they are=20= essentially reactive, and the A3515LUA noise sources are due to resistance.<= /BLOCKQUOTE>

      Perhaps I should have made it clear= er that the resolution that I quoted for the A3515 based linear magnetic det= ector was actually measured and was determined for 30 sec periods, peak to p= eak. The above characteristic agrees with my readings fairly well. The 400 m= icro V RMS =3D 566 micro V pk (presumably over 1/10 sec), but the bandwidth=20= is only 10 Hz so the rough noise estimate is ~ 18 micro V and this is a 'typ= ical' single deviation value only. You may get about 2 standard deviations o= ver longer periods. After taking into account some increase in low frequency= noise levels and adding power supplies, an amplifier and filter, my <100= micro V resolution is not too bad. It can be further reduced if you opt for= 3 Hz or less bandwidth. The overall range is ~40,000, which is better than=20= the 14 true bits (16,384 - 84dB) you get out of most nominally 16 bit A/D co= nverters.

   A more s= ubtle problem is another noise called the 1/f or flicker noise problem in se= miconductors.  This noise also rises as the frequency goes down.  = So the numbers for the A3515LUA will almost surely get worse as we go down i= n frequency for a seismometer.  In particular, 10 Hz is high, when we w= ant to look at teleseismic events, which is exactly where we need good low n= oise performance.


      This was why I was so pleased when=20= I learnt about the A3515s! I had been working with A3505s previously and the= y were significantly noisier at the low frequencies. However, Allegro put a=20= chopper amplifier in the A3515 which rejects most 1/f no= ise and this is exactly what we need for the longer pe= riod seismic observations! They are uniquely well suited to th= is application.

      One note: the output impedance of a= n A3515 is very low and there is some very wide band noise on it. This can b= e rejected by connecting a 4.7 mH choke and a 10 nF ceramic capacitor to the= output pin. A 100 nF ceramic capacitor should be connected across the suppl= y lines close to the device.=20
=20
   One way=20= around 1/f noise is the carrier amplifier, i.e., if you put the information=20= on a carrier frequency, amplify this carrier frequency, then demodulate, you= step around the 1/f problem.  Coincidentally, this is exactly what hap= pens in capacitative and inductive displacement sensors.=20
A high frequency is impressed across the sensor capacitor (or inductor).=  This capacitor changes value according to the displacement, yielding=20= (modulating) that high frequency (carrier) which is amplified by a carrier a= mplifier. The output of that carrier amplifier is then detected and filtered= at a high level where the 1/f, thermal and current noises are well below th= e output.  So, you'll note that Sean-Thomas used an inductive sensor on= his vertical seismometer.  That is one route.
Another is that you could easily build the design idea "Circuit resolves
0.1-fF change from 100 pF by Derek Redmayne, Linear Technology Corp,
Milpitas, CA  (from EDN Access Design Ideas1/6/2000)" at:
www.e-insite.net/ednmag/index.asp?layout=3Darticle&articleId=3DCA464= 62&pubdate=3D01/06/2000
The major cost of the semis in quantities of one would be about $32, but= this includes a 24 bit digitizer sampling at 7.5 samples/second.=20
Resolving a 0.1 fF change in 100 pF is a 1,000,000 to 1, or 120 dB
range.  


      This looks like the most promising=20= candidate for the differential capacity measurements that we need. The gain=20= is only two, but this could easily be increased and two off two pole filters= , a high pass filter ~40 sec and an output amplifier added to give a complet= e system. If you used a +/- 10 mm range for a Lehman, the step size for a 14= bit true A/D would be about 1.2 microns. To allow for drift you add a high=20= pass filter and then amplify the signal x100, or as convenient. The gives hi= gh resolution and is not sensitive to slow drifts. You could add a 'cheap' t= uning 10 V movng coil meter to the direct output to read off the position of= the arm, to know when it needs re-centering.

One measure to decide if this is sufficient. Sean-Thomas=20
mentioned in an email post=20= of Nov 15, 2000 to the PSN list that, "The normal background noise for a sei= smometer like a Lehman are the 6-second microseisms, usually caused by storm= s off the east coast.  Away from the immediate shore (100km) these run=20= 2 to 4 microns peak-to-peak=E2=80=A6"  So for ease of computation, let'= s set a goal of 1 micron.  Therefore the capacitor plates could be set=20= apart by 1e6 * 1micron, or 1 meter and we could still resolve the mechanical= background.  Practical construction might be to have parallel plates a= bout 10 mm away on each side (~1/2 inch) from a moving plate on a SG pendulu= m.  Then for 100 pf between the plates we need: C =3D 2.249E-13 * Er *=20= sq.in * (N-1) / (in of separation) so rearranging, substituting and solving=20= we get that we need 222 sq.in
of area.  Not good.  but lets reduce the spacing to about 0.05= " and we get 22 sq.in or a plate a bit over 4.5" square.  This is doabl= e.


      You need to check on air damping fo= r sizeable capacitor plates which move toward or away from each other. This=20= can be a serious limitation and there are 'guideline' estimates.=20

A variation would be to salvage the parallel plates of a variable tunin= g capacitor such=20
as in a broadcast receiver.=  Fully meshed, the large gang was 365 pF.  So, mount so the pendu= lum meshes the group.  Now you have perhaps a 1" range with about 300 p= F change.


      Maintaining the alignment could be=20= just a bit difficult with an ex radio variable capacitor and they are of a r= ather odd shape, designed to give a ~linear wavelength scale. The high volta= ge transmitter types have larger spacing. It would probably be both easier a= nd more satisfactory to make a variable area plate capacitor out of sheet br= ass and spacers.=20

Another solution would be to implement a slightly different circuit such= =20
as the one in the SETRA pat= ents: 4,054,833: 5,194,819: and 6,316,948. Now the amplifier can provide gai= n, and the voltage tracks the ratio of bridge caps, so small capacitance cha= nges generate larger voltages and therefore you could use smaller single pla= te sensors.
An example of this was the design idea "Bridge Measures Small Capacitanc= e" by Jeff Witt, Linear Technology Corp, in Electronic Design, Nov. 4, 1996,= pg. 110.


      See http://www.linear.com/pdf/an87.= pdf page 87 for this article.

      This circuit is designed to measure= a variable capacity with reference to a fixed capacity using an integrating= feedback path. One problem with seis sensors is that the variable capacity=20= also varies with temperature, at about 20 ppm / C Deg for Brass. This does n= ot sound a lot, but if the full sensor range was 20 mm, this would represent= 0.4 micron / C deg, when we may be interested in quake signals down to 1/40= of this or less. You could, however, make a fixed reference capacitor out o= f the same materials. A differential capacity arrangement only experiences t= he 20 ppm variation on the difference, not on the overall capacity - the zer= o should be designed to be ~constant with temperature. They are also less se= nsitive to eccentric movement / wobbles at right angles to the normal moveme= nt. The 'professional' type sensor that I looked at was made from silver pla= ted invar.

This circuit seemed to be similar to the SETRA circuits and allow gain.=  
This final circuit is proba= bly the best compromise of the lot.  Take it and add the 24 bit A/D, LT= C2400, and you have a powerful combination for low cost.  Since the ini= tial output is analog, you have a node that can be fed back to the force coi= l on the SG and at the same time you get a simple digital stream to feed you= r computer.


      The signals which you wish to resol= ve and record will be of different frequency and may be far lower in amplitu= de than the ocean microseisms - maybe 1% the size. Having to record large 'n= oise' signals at the same time as much smaller quake signals puts definite l= imits on the signal processing.=20
 
      It is a pity that the LTC2400 is on= ly available in a SOIC miniature package.

Oh, yes, an excellent refer= ence for capacitance sensor design: "Capacitive Sensors, Design and Applicat= ions," by Larry K. Baxter, IEEE Press.


      I agree! It is very good and descri= bes a lot of very diverse practical applications in detail. ISBN =3D 0780353= 51X. Unfortunately, the paperback edition is $99-95 new, but you might try y= our library.

      Regards,

      Chris Chapman
Subject: New Lehman on line (almost) From: "Jan D. Marshall" jandmarshall@............ Date: Sun, 29 Sep 2002 13:17:44 -0600 After about 12 months of thinking, planning and working (and procrastinating) I finally have my seismograph up and working. I now need your expert input on what I did wrong or adjustment that I need to make to get things fine tuned (or maybe coarsely tuned). Please visit my web site www.cableone.net/jandmarshall and choose the Seismic Page to view my project. Problems I note right off 1 - I have a 4-5 hz oscillation in the pendulum. 2 - I seem to have a lot of environmental noise -- I can not correlate it with actions in the house 3 - Am I damped enough?? I am open to all comments and suggestions -- just remember this is my first attempt at building a seismograph! Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID
After = about 12=20 months of thinking, planning and working (and procrastinating) I finally = have my=20 seismograph up and working.  I now need your expert input on what I = did=20 wrong or adjustment that I need to make to get things fine tuned (or = maybe=20 coarsely tuned).
 
Please = visit my web=20 site www.cableone.net/jandmarsha= ll=20 and choose the Seismic Page to view my project.
 
Problems I note=20 right off
   =20 1 - I have a 4-5 hz oscillation in the = pendulum.
    2=20 - I seem to have a lot of environmental noise -- I can not = correlate it=20 with actions in the house
    3=20 - Am I damped enough??
 
I am = open to all=20 comments and suggestions -- just remember this is my first attempt at = building a=20 seismograph!

Jan=20 Marshall
jandmarshall@............
www.cableone.net/jandmarshallNampa,=20 ID

 
Subject: Re: New Lehman on line (almost) From: ChrisAtUpw@....... Date: Sun, 29 Sep 2002 17:24:26 EDT In a message dated 29/09/02, jandmarshall@............ writes: > Please visit my web site www.cableone.net/jandmarshall and choose the > Seismic Page to view my project. > > Problems I note right off > 1 - I have a 4-5 hz oscillation in the pendulum. > 2 - I seem to have a lot of environmental noise -- I can not correlate > it with actions in the house > Hi Jan, The photos are a great help. What is the weight of the seismic mass on the end of the arm? What undamped oscillation period are you getting? Only you can check the damping. Deflect the beam a very small amount, maybe by putting a screwdriver etc near it, let it go and observe it. The pendulum should swing back to the zero position, but it should not go beyond zero and come back, or show any actual oscillations. The bearings, general construction etc look fine. Check for electrical activity in the house / movement of magnetic materials, even cars / trains outside etc to search for the environmental noise. Does the seis react when the fridge / cooker / central heating switches on / off? It is more usual to put both magnets on the baseplate and the coil and damping plate on the arm. With unscreened magnets on the arm, it can and will pick up any small changes in the local environmental magnetic field. From the photos, I can't see where the pick up coil is in relation to it's magnet. The centre line of the coil should be roughly on the end face of the magnet with your setup. The 5 Hz could be due to the whole arm system nodding up and down or side to side. Try tapping the end post with your finger and see if you get this sort of frequency response. With your coil system as shown, you will likely pick up both vertical and horizontal movements of the arm. What amplifier / filter / A/D system are you using? What is the cut-off frequency of the filter? Regards, Chris Chapman In a message dated 29/09/02, jandmarshall@............ writes:

Please visit my web site www.cableone.net/jandmarshall and choose the Seismic Page to view my project.

Problems I note right off
   1 - I have a 4-5 hz oscillation in the pendulum.
   2 - I seem to have a lot of environmental noise -- I can not correlate it with actions in the house
   3 - Am I damped enough?


Hi Jan,

      The photos are a great help.

      What is the weight of the seismic mass on the end of the arm?

      What undamped oscillation period are you getting?

      Only you can check the damping. Deflect the beam a very small amount, maybe by putting a screwdriver etc near it, let it go and observe it. The pendulum should swing back to the zero position, but it should not go beyond zero and come back, or show any actual oscillations.

      The bearings, general construction etc look fine. Check for electrical activity in the house / movement of magnetic materials, even cars / trains outside etc to search for the environmental noise. Does the seis react when the fridge / cooker / central heating switches on / off? It is more usual to put both magnets on the baseplate and the coil and damping plate on the arm. With unscreened magnets on the arm, it can and will pick up any small changes in the local environmental magnetic field.

      From the photos, I can't see where the pick up coil is in relation to it's magnet. The centre line of the coil should be roughly on the end face of the magnet with your setup.

      The 5 Hz could be due to the whole arm system nodding up and down or side to side. Try tapping the end post with your finger and see if you get this sort of frequency response. With your coil system as shown, you will likely pick up both vertical and horizontal movements of the arm.

      What amplifier / filter / A/D system are you using? What is the cut-off frequency of the filter?

      Regards,

      Chris Chapman
Subject: RE: New Lehman on line (almost) From: "Jan D. Marshall" jandmarshall@............ Date: Sun, 29 Sep 2002 15:52:18 -0600 see my comments beside your questions below -- Jan M Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of ChrisAtUpw@....... Sent: Sunday, September 29, 2002 3:24 PM To: psn-l@.............. Subject: Re: New Lehman on line (almost) In a message dated 29/09/02, jandmarshall@............ writes: Please visit my web site www.cableone.net/jandmarshall and choose the Seismic Page to view my project. Problems I note right off 1 - I have a 4-5 hz oscillation in the pendulum. 2 - I seem to have a lot of environmental noise -- I can not correlate it with actions in the house 3 - Am I damped enough? Hi Jan, The photos are a great help. What is the weight of the seismic mass on the end of the arm? right at 5 pounds What undamped oscillation period are you getting? about 12 - 14 sec Only you can check the damping. Deflect the beam a very small amount, maybe by putting a screwdriver etc near it, let it go and observe it. The pendulum should swing back to the zero position, but it should not go beyond zero and come back, or show any actual oscillations. OK -- I am not damped enough -- It oscillates about 4-5 times The bearings, general construction etc look fine. Check for electrical activity in the house / movement of magnetic materials, even cars / trains outside etc to search for the environmental noise. Does the seis react when the fridge / cooker / central heating switches on / off? It is more usual to put both magnets on the baseplate and the coil and damping plate on the arm. With unscreened magnets on the arm, it can and will pick up any small changes in the local environmental magnetic field. I will consider this From the photos, I can't see where the pick up coil is in relation to it's magnet. The centre line of the coil should be roughly on the end face of the magnet with your setup. See the 6th picture down -- The 5 Hz could be due to the whole arm system nodding up and down or side to side. Try tapping the end post with your finger and see if you get this sort of frequency response. With your coil system as shown, you will likely pick up both vertical and horizontal movements of the arm. I lowered the right end a tiny bit -- the LF oscillations appear to have stopped What amplifier / filter / A/D system are you using? What is the cut-off frequency of the filter? I am using Larry Cochran's Serial A/D board and his Filter/Amp both stock as I received them -- I am using his coil also Regards, Chris Chapman
see my=20 comments beside your questions below -- Jan M
 

Jan=20 Marshall
jandmarshall@............
www.cableone.net/jandmarshallNampa,=20 ID

-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of=20 ChrisAtUpw@.......
Sent: Sunday, September 29, 2002 3:24 = PM
To: psn-l@..............
Subject: Re: New = Lehman on=20 line (almost)

In a = message dated=20 29/09/02, jandmarshall@............ writes:

Please visit my web site = www.cableone.net/jandmarshall and=20 choose the Seismic Page to view my project.

Problems I note = right=20 off
   1 - I have a 4-5 hz oscillation in the = pendulum.=20
   2 - I seem to have a lot of environmental = noise -- I=20 can not correlate it with actions in the house =
   3 - Am=20 I damped enough?


Hi=20 Jan,

      The photos are a = great help.=20

      What is the weight of the = seismic=20 mass on the end of the arm?  right at 5=20 = pounds 


      Wha= t=20 undamped oscillation period are you getting?  about 12 - = 14=20 sec

      Only you = can=20 check the damping. Deflect the beam a very small amount, maybe by = putting a=20 screwdriver etc near it, let it go and observe it. The pendulum should = swing=20 back to the zero position, but it should not go beyond zero and come = back, or=20 show any actual oscillations.  OK -- I am not damped enough -- It = oscillates about=20 4-5 = times 


      The = bearings, general construction etc look fine. Check for electrical = activity in=20 the house / movement of magnetic materials, even cars / trains outside = etc to=20 search for the environmental noise. Does the seis react when the = fridge /=20 cooker / central heating switches on / off? It is more usual to put = both=20 magnets on the baseplate and the coil and damping plate on the arm. = With=20 unscreened magnets on the arm, it can and will pick up any small = changes in=20 the local environmental magnetic field.  I will consider = = this 

      From = the=20 photos, I can't see where the pick up coil is in relation to it's = magnet. The=20 centre line of the coil should be roughly on the end face of the = magnet with=20 your setup.  See=20 the 6th picture down=20 = --  

      T= he 5=20 Hz could be due to the whole arm system nodding up and down or side to = side.=20 Try tapping the end post with your finger and see if you get this sort = of=20 frequency response. With your coil system as shown, you will likely = pick up=20 both vertical and horizontal movements of the arm.  I lowered = the right=20 end a tiny bit -- the LF oscillations appear to have=20 = stopped 

      Wh= at=20 amplifier / filter / A/D system are you using? What is the cut-off = frequency=20 of the filter?  I=20 am using Larry Cochran's Serial A/D board and his Filter/Amp both = stock as I=20 received them -- I am using his coil=20 = also 

      Regar= ds,=20

      Chris Chapman
=20
Subject: Re: New Lehman on line (almost) From: meredithlamb meredithlamb@............. Date: Sun, 29 Sep 2002 20:44:10 -0600 Hi Jan, Nice construction! Thanks for all the photos! Have to agree with Chris about the magnet and coil...it would generate less "noise" if they were reversed to where the magnet is on the base, and the coil is on the boom. One could even use say.....fine enameled magnet wire hanging down from higher up on the mast and loosely draping onto the boom and its coil connection.....or "looped" (gives it room to flex) over the top of the mast and going down your suspension mechanism. I'd guess over 70% of the displayed seismogram "noise" would disappear if done in this enhancement fashion. Take care, Meredith "Jan D. Marshall" wrote: > After about 12 months of thinking, planning and working (and > procrastinating) I finally have my seismograph up and working. I now > need your expert input on what I did wrong or adjustment that I need > to make to get things fine tuned (or maybe coarsely tuned). Hi Jan,

Nice construction!  Thanks for all the photos!

Have to agree with Chris about the magnet and coil...it would
generate less "noise" if they were reversed to where the magnet
is on the base, and the coil is on the boom. One could even use
say.....fine enameled magnet wire hanging down from higher up
on the mast and loosely draping onto the boom and its coil
connection.....or "looped" (gives it room to flex) over the top
of the mast and going down your suspension mechanism.  I'd
guess over 70% of the displayed seismogram "noise" would
disappear if done in this enhancement fashion.

Take care, Meredith

"Jan D. Marshall" wrote:

After about 12 months of thinking, planning and working (and procrastinating) I finally have my seismograph up and working.  I now need your expert input on what I did wrong or adjustment that I need to make to get things fine tuned (or maybe coarsely tuned).
Subject: Re: New Lehman on line (almost) From: Thomas W Leiper twleiper@........ Date: Tue, 29 Oct 2002 23:32:07 -0500 On Sun, 29 Sep 2002 15:52:18 -0600 "Jan D. Marshall" writes: With your coil system as shown, you will likely pick up both vertical and horizontal movements of the arm. I agree with that, in fact it would probably be more sensitive to vertical than horizontal. I would mount the magnet on the side of the arm and have it move toward and away from the coil. You'll have to balance it, of course, but you could always put your damping magnet on the opposite side and have it move around a nice chunk of CU. Tom
On Sun, 29 Sep 2002 15:52:18 -0600 "Jan D. Marshall" <jandmarshall@............>= =20 writes:
With your coil system as shown, = you will=20 likely pick up both vertical and horizontal movements of the=20 arm.
 
I agree with that, in = fact it would=20 probably be more sensitive to vertical than horizontal.
I would mount the magnet= on the=20 side of the arm and have it move toward and away
from the coil. You'll = have to=20 balance it, of course, but you could always put your
damping magnet on the = opposite side=20 and have it move around a nice chunk of CU.
 
Tom
Subject: RE: New Lehman on line (almost) From: Ron Westfall westfall@....... Date: Mon, 30 Sep 2002 09:14:13 -0700 Hi Jan From your recordings, your environmental noise looks like cultural noise from your local community. Notice how it winds up early in the morning when people get up and stays constant through to about bedtime. The intensity of this type of noise will depend on where you live: urban or rural, party zone or non-party zone (just kidding). Try everybody else's suggestions, but if you still have too much noise, you might consider turning down the amplification on the preamp. Another thought that just occurred to me ... do you have a temperature controlled housing over the seismograph? Slight air motions due to thermal gradients, etc. in the house will create noise. I think most people have put a housing over their seismograph and use some arrangement to heat the interior air near the top of the housing by a few degress. This creates stagnant layers of air that do not circulate, because the top is hotter than the bottom. If it were the reverse, you would get convective air motion that would be picked up by the seismograph. If you ask an appropriate question of the list, I am sure that you will get more advice than you could ever possibly use on various ways to build such a housing. It sounds like you have solved your 4 - 5 Hz oscillation, but in case it reappears or your current solution has to be revisited ... As Chris has pointed out, your oscillation is almost surely a mechanical vibration/motion in the seismograph itself. I am not a materials expert, but vibration seems to be strongly correlated to stiffness. Your post, base, and supporting I-beams look solid as rock. The boom also looks relatively stiff. I would be suspicious however of the two diagonal boom support rods. With their round and relatively thin cross-section, they are individually prone to vibration and you will get interesting beat frequencies from the combination of two of them vibrating. It takes very little vibration in these rods to affect the recording. Hope this was useful, Ron Westfall -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Jan D. Marshall Sent: Sunday, September 29, 2002 12:18 PM To: Sesmic List Server Subject: New Lehman on line (almost) After about 12 months of thinking, planning and working (and procrastinating) I finally have my seismograph up and working. I now need your expert input on what I did wrong or adjustment that I need to make to get things fine tuned (or maybe coarsely tuned). Please visit my web site www.cableone.net/jandmarshall and choose the Seismic Page to view my project. Problems I note right off 1 - I have a 4-5 hz oscillation in the pendulum. 2 - I seem to have a lot of environmental noise -- I can not correlate it with actions in the house 3 - Am I damped enough?? I am open to all comments and suggestions -- just remember this is my first attempt at building a seismograph! Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID
Hi Jan
 
From your recordings, your environmental noise looks like cultural noise from your local community.  Notice how it winds up early in the morning when people get up and stays constant through to about bedtime.  The intensity of this type of noise will depend on where you live: urban or rural, party zone or non-party zone (just kidding).  Try everybody else's suggestions, but if you still have too much noise, you might consider turning down the amplification on the preamp.
 
Another thought that just occurred to me ... do you have a temperature controlled housing over the seismograph?  Slight air motions due to thermal gradients, etc. in the house will create noise.  I think most people have put a housing over their seismograph and use some arrangement to heat the interior air near the top of the housing by a few degress.  This creates stagnant layers of air that do not circulate, because the top is hotter than the bottom.  If it were the reverse, you would get convective air motion that would be picked up by the seismograph.  If you ask an appropriate question of the list, I am sure that you will get more advice than you could ever possibly use on various ways to build such a housing. <smile>
 
It sounds like you have solved your 4 - 5 Hz oscillation, but in case it reappears or your current solution has to be revisited ... As Chris has pointed out, your oscillation is almost surely a mechanical vibration/motion in the seismograph itself.  I am not a materials expert, but vibration seems to be strongly correlated to stiffness.  Your post, base, and supporting I-beams look solid as rock.  The boom also looks relatively stiff.  I would be suspicious however of the two diagonal boom support rods.  With their round and relatively thin cross-section, they are individually prone to vibration and you will get interesting beat frequencies from the combination of two of them vibrating.  It takes very little vibration in these rods to affect the recording.
 
Hope this was useful,
Ron Westfall
 
  -----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@...............On Behalf Of Jan D. Marshall
Sent: Sunday, September 29, 2002 12:18 PM
To: Sesmic List Server
Subject: New Lehman on line (almost)

After about 12 months of thinking, planning and working (and procrastinating) I finally have my seismograph up and working.  I now need your expert input on what I did wrong or adjustment that I need to make to get things fine tuned (or maybe coarsely tuned).
 
Please visit my web site www.cableone.net/jandmarshall and choose the Seismic Page to view my project.
 
Problems I note right off
    1 - I have a 4-5 hz oscillation in the pendulum.
    2 - I seem to have a lot of environmental noise -- I can not correlate it with actions in the house
    3 - Am I damped enough??
 
I am open to all comments and suggestions -- just remember this is my first attempt at building a seismograph!

Jan Marshall
jandmarshall@............
www.cableone.net/jandmarshall
Nampa, ID