PSN-L Email List Message

Subject: Re: Measuring Time Delay
From: GeE777@.......
Date: Mon, 10 Jan 2000 14:15:41 EST

In a message dated 1/9/00 6:46:37 PM Pacific Standard Time, 
ChrisAtUpw@....... writes:

>      Have you tried testing a geophone by sitting it on a flat plate on 
>  li-lo cushion filled with water? Then use a syringe to inject a ml of 
>      An impulse could be given to a horizontal seismometer by discharging a 
>  capacitor through a nearby coil of wire. The induced currents give a 
>  repulsive force.

Hello All,

Any pulse you record by droping water or beads records too much of the 
enviroment around the geophone.
If you take a step function response like I recorded it, and get the second 
derivative of this signal, you will have an impulse response of the geophone 
with little effects of the surrounding area.  Use a pulse generator to get 
the imulse response of the rest of your electronic system. With thee two 
signals, you can derive an entire system response and remove any undesired 
system response from your seismic data.  Exploration seismoligists like to 
work with data that has not been phase distorted by geophones and/or 
amplifiers, etc.

I have also used this same method to record the step function of horizontal 

George Erich
on the  +  side


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Larry Cochrane <cochrane@..............>