In a message dated 08/06/2006, gpayton880@....... writes:

Entering  a new "hobby" or interest, one always has a ton of questions.  But, 
 
to avoid ruining my welcome too fast, I will list just a few general  
questions.  
Hi Gerald,
 
    I suggest that you download and read 
_http://psn.quake.net/info/analysis.pdf_ (http://psn.quake.net/info/analysis.pdf)    It describes the main 
characteristics of earthquakes.

1)   Geophone vs. Seismometer?
2)    Vertical or  Horizontal?
3)    Resonant Frequency? 1, 4.5, 8, or  10Hz.?
    Working back up the list, 8 or 10 Hz geophones are  all but useless for 
detecting earthquakes, unless you live on a live volcano.  When a frequency of 
say 10 Hz is quoted, this is the natural resonant frequency.  They are 
normally critically damped and the upper limit may be over 20x this and  quite flat 
to velocity. 
 
    Earthquakes generate fast compressional P waves (1  to 0.5 sec and less), 
slower lateral S waves (2 to 1 sec and less) and when  these interact with 
the earth's surface, long period lateral Love waves and  vertical Rayleigh waves 
are generated (10 to >40 sec).
    Notice that you do need to consider the  polarisation as well as the 
period. The higher frequencies generated at the  quake source are selectively 
absorbed as they travel through the earth.
 
    It is usual to limit amateur systems with a low  pass filter set at 10 or 
20 Hz. This greatly reduces the ambient cultural noise,  which may be severe 
at over 20 Hz.
 
    While 4.5 Hz geophones can be used 'as supplied'  for local quakes, they 
are of quite limited use for regional quakes and may only  sense very large 
teleseismic quakes. They are, however, reasonably inexpensive.  New ones may 
cost $60 each. Larry has some secondhand three axis  ones in waterproof plastic 
containers, from $58.
    The response can be extended down to 0.5 Hz (2 sec)  using a compensating 
amplifier. These do add some noise, but they are reasonably  good and do then 
enable you to pick up both regional and teleseismic P and S  waves. 
 
    1 Hz geophones are generally OK and are used in  geophysical fieldwork, 
but they are much more expensive. New ones cost about  $1,500.

I have  spent hours today reading various articles and from different 
websites  until my eyes crossed and I had Brain Fade.  Some of the material  
"may" be outdated too. That is one of my "gripes" about the  
internet.......no way to determine the age of a posted  document.
    One source of dated information is psn letters. You  can download 4 parts 
per year, expand them and put them into an annual  file. This can then be 
searched using your word processor.

As I  understand it, for long distance reception, you need a more sensitive  
seismometer rather than a geophone. However, I could see where a  sensitive 
one might be overwhelmed with a nearby quake. I live in a  rural area in NW 
Arkansas and the closest activity probably would be the  New Madrid fault 
area.
    You can buy boards with one to three 'strong  motion' sensors on them, 
but they tend to be fairly expensive. They are likely  to be limited by internal 
noise.

I doubt  that I want to build anything unless it is a kit form. Is there an  
soundboard interface software or hardware nowadays. Where are the  
economical commercial, kits and ready-built systems  available?
    The 1 and 4.5 Hz geophones will give you signals  limited primarily by 
your ambient local noise. For longer period signals, you  need to use Lehman or 
SG seismometers.
 
    There are no US kits as far as I know. This is very  much a DIY hobby. 
You can buy the electronic amplifiers, ADCs and GPS time  receivers. You can buy 
a simple 'demonstration' vertical as used in some  schools, see 
_http://jclahr.com/science/psn/as1/index.html_ 
(http://jclahr.com/science/psn/as1/index.html)  
 
    The nearest thing to a kit is the complete  electronics for a SG 
seismometer sold by Larry. You just have to make a pendulum  of about 1 sec period. 
This will give you sensitivity to horizontal motion flat  from about 20 sec to 
10 Hz

Amateur  Radio is full of different interfaces and uses for a  soundboard.
    Work it out! You are considering recording maybe  three data channels 
over periods of years. Even at their lowest rate,  soundboards would generate 
hopelessly large data files. 
    You need maybe 20 samples / sec at 16 bits  resolution per channel. You 
also have to scan for and analyse the seismic  signals. This requires 
specialist software. 
    You need a clock timing system which is accurate to  better than 0.5 sec 
at all times. The software clocks on PCs may show  errors of 30 sec per day. 
The 'sort-of' clock which behaves  least like a clock! An alternative is to use 
an accurate on-line  time service like 'AboutTime' from  
_http://www.arachnoid.com/abouttime/_ (http://www.arachnoid.com/abouttime/)    Only a few on-line 
services check for propagation delays, which can be up to  several seconds due 
to digital queueing on the internet, if you are  unlucky. You may also search 
for a 'local' time server which has an analogue  phone connection.
 
    Hope that this helps!
 
`   Chris Chapman










In a message dated 08/06/2006, gpayton880@....... writes:
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>Entering=20
  a new "hobby" or interest, one always has a ton of questions.  But,=20
  
to avoid ruining my welcome too fast, I will list just a few general=20
  
questions.  
Hi Gerald,
 
    I suggest that you download and read http://psn.quake.net/info/an=
alysis.pdf =20
It describes the main characteristics of earthquakes.
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>1) =20
    Geophone vs. Seismometer?
2)    Vertical or=20
  Horizontal?
3)    Resonant Frequency? 1, 4.5, 8, or=20
10Hz.?
    Working back up the list, 8 or 10 Hz geophones=20=
are=20
all but useless for detecting earthquakes, unless you live on a live volcano=
..=20
When a frequency of say 10 Hz is quoted, this is the natural resonant freque=
ncy.=20
They are normally critically damped and the upper limit may be over 20x this=
 and=20
quite flat to velocity. 
 
    Earthquakes generate fast compressional P waves=
 (1=20
to 0.5 sec and less), slower lateral S waves (2 to 1 sec and less) and when=20
these interact with the earth's surface, long period lateral Love waves and=20
vertical Rayleigh waves are generated (10 to >40 sec).
    Notice that you do need to consider the=20
polarisation as well as the period. The higher frequencies generated at the=20
quake source are selectively absorbed as they travel through the earth.
 
    It is usual to limit amateur systems with a low=
=20
pass filter set at 10 or 20 Hz. This greatly reduces the ambient cultural no=
ise,=20
which may be severe at over 20 Hz.
 
    While 4.5 Hz geophones can be used 'as supplied=
'=20
for local quakes, they are of quite limited use for regional quakes and may=20=
only=20
sense very large teleseismic quakes. They are, however, reasonably inexpensi=
ve.=20
New ones may cost $60 each. Larry has some secondhand three axis=20
ones in waterproof plastic containers, from $58.
    The response can be extended down to 0.5 Hz (2=20=
sec)=20
using a compensating amplifier. These do add some noise, but they are reason=
ably=20
good and do then enable you to pick up both regional and teleseismic P and S=
=20
waves. 
 
    1 Hz geophones are generally OK and are used in=
=20
geophysical fieldwork, but they are much more expensive. New ones cost about=
=20
$1,500.
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>I have=20
  spent hours today reading various articles and from different 
websites=
=20
  until my eyes crossed and I had Brain Fade.  Some of the material=20
  
"may" be outdated too. That is one of my "gripes" about the=20
  
internet.......no way to determine the age of a posted=20
document.
    One source of dated information is psn letters.=
 You=20
can download 4 parts per year, expand them and put them into an annual=20
file. This can then be searched using your word processor.
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>As I=20
  understand it, for long distance reception, you need a more sensitive=20
  
seismometer rather than a geophone. However, I could see where a=20
  sensitive 
one might be overwhelmed with a nearby quake. I live in=
 a=20
  rural area in NW 
Arkansas and the closest activity probably would be t=
he=20
  New Madrid fault 
area.
    You can buy boards with one to three 'stro=
ng=20
motion' sensors on them, but they tend to be fairly expensive. They are like=
ly=20
to be limited by internal noise.
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>I doubt=20
  that I want to build anything unless it is a kit form. Is there an=20
  
soundboard interface software or hardware nowadays. Where are the=20
  
economical commercial, kits and ready-built systems=20
available?
    The 1 and 4.5 Hz geophones will give you signal=
s=20
limited primarily by your ambient local noise. For longer period signals, yo=
u=20
need to use Lehman or SG seismometers.
 
    There are no US kits as far as I know. This is=20=
very=20
much a DIY hobby. You can buy the electronic amplifiers, ADCs and GPS time=20
receivers. You can buy a simple 'demonstration' vertical as used in some=20
schools, see http://jclahr.com/scie=
nce/psn/as1/index.html 
 
    The nearest thing to a kit is the complete=20
electronics for a SG seismometer sold by Larry. You just have to make a pend=
ulum=20
of about 1 sec period. This will give you sensitivity to horizontal motion f=
lat=20
from about 20 sec to 10 Hz
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>Amateur=20
  Radio is full of different interfaces and uses for a=20
soundboard.
    Work it out! You are considering recording mayb=
e=20
three data channels over periods of years. Even at their lowest rate,=20
soundboards would generate hopelessly large data files. 
    You need maybe 20 samples / sec at 16 bits=20
resolution per channel. You also have to scan for and analyse the seism=
ic=20
signals. This requires specialist software. 
    You need a clock timing system which is accurat=
e to=20
better than 0.5 sec at all times. The software clocks on PCs may show=20
errors of 30 sec per day. The 'sort-of' clock which behaves=
=20
least like a clock! An alternative is to use an accurate on-li=
ne=20
time service like 'AboutTime' from  http://www.arachnoid.com/aboutt=
ime/ =20
Only a few on-line services check for propagation delays, which can be up to=
=20
several seconds due to digital queueing on the internet, if you are=20
unlucky. You may also search for a 'local' time server which has an analogue=
=20
phone connection.
 
    Hope that this helps!
 
`   Chris Chapman