J=F3n,

There is some type of very high frequency signal entering the system. =
This
has nothing to do with the geophones. They appear to be functioning
adequately because all three channels are responding to discreet events.

Have you connected the shield wire to the ground connection on the board
yet?

If you have, and you still are getting the spikes, then the next step is =
to
do as others have suggested -- disconnect the cables from the board and
place a (approx 330 ohm) resistor across the + & - terminals for each of =
the
channels. Run the board for a few minutes -- there should be a flat =
response
with no spikes. If you do get spikes then a RF signal is getting into =
the
board and/or computer.

If there are no spikes after several minutes of operation, then =
disconnect
the wires at the geophone case and use the same resistors to shunt the =
ends
of the cables. If no spikes occur then the problem is probably in the =
wiring
going to the transducers -- check the soldered connections. (All of your
connections are soldered aren't they? If not, then do so.)

I've had over 300 meters of cable strung out between geophones and my =
ADC
system along a 600-volt light rail train track -- and had no problems =
with
spikes entering the system -- even during thunderstorms.


-Tim-

Timothy Carpenter
5043 Whitlow Court
Commerce Township, Michigan 48382
geodynamics@....... (secondary)

-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... =
On
Behalf Of J=F3n Fr=EDmann
Sent: Monday, June 05, 2006 6:31 PM
To: psn-l@..............
Subject: RE: spike problem

Hi

Is it possible that this spikes might come becose of a sensor failure ?

The smaller spikes didn't start until I did connect the cat-5 cable
directly to the geophone sensors. They still are there, even if I have
reconnected the orginal wires.

Just a thought.

Regards.
--=20
J=F3n Fr=EDmann
http://www.jonfr.com
http://www.simnet.is/jonfr500/earthquake/

__________________________________________________________

Public Seismic Network Mailing List (PSN-L)


__________________________________________________________

Public Seismic Network Mailing List (PSN-L)