I agree
they seems to be electic problem but related to connections
check carefully your connectors.
That effect is due to the big spikes (often originated by the connector
that don't press so well) then the High Pass filter modify the DC level
in the way I see on the chart.

Hope this helps.
Regards
mauro


At 09:02 28/06/2004, you wrote:
>Tom,
>
>This looks like an electrical problem rather then a problem with the sensor.
>Is the signal from the sensor going through one of my Amp/Filter boards? If
>it is you may want to send it back to me so I can check it out.
>
>Larry Cochrane
>Redwood City, PSN
>
>----- Original Message -----
>From: "tdick" 
>To: 
>Sent: Sunday, June 27, 2004 7:22 AM
>Subject: distortion on geophones
>
>
>Before I dig up my geophone which are about four feet down in my rose bed --
>I am trying to figure out if this distortion of wave form is due to water in
>the bottom of the hole or due to a changes in the amplifier. On local mine
>blasts I am getting distortion while on earthquakes I am not. I have posted
>some examples at this site
>
>http://Dad.bachcottage.com
>
>it will look like a drive on your computer, open folder called Distortion on
>geophones
>
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