PSN-L Email List Message

Subject: Re: Winquake
From: Pete Rowe ptrowe@.........
Date: Sun, 20 Apr 2008 17:26:27 -0700 (PDT)

The problem with clipping is in the amplifiers ahead of the A/D. You can run the overall gain down a little and see if that helps. You would really like to know which stage is clipping and then adjust the gain until it doesn't. Ideally you would put a very small sine wave signal (1 Hz?) into the input of the amplifier chain in place of the coil. Then run the input level up until you get clipping at the A/D. Then, with an oscilloscope, trace through all of your stages to see where the clipping is occurring. You may want to re-distribute the gain or just reduce it to where you are happy with the way it performs on local quakes.
I have many earthquakes in the less than magnitude 3 range (maybe 30 a month)and my A/D isn't anywhere near saturation. Yet, I can see a 7.0 anywhere on earth.

Good luck and let us all know how you are progressing.

--- On Sun, 4/20/08, Thomas Dick  wrote:

> From: Thomas Dick 
> Subject: Winquake
> To: psn-l@..............
> Date: Sunday, April 20, 2008, 6:06 AM
> An unusual problem that I am sure those of you in California
> have solved. These southern Illinois quakes that are over
> about a Magnitude of 3 and less than fourty miles away
> appear to overloaded my system causing clipping at peaks.
> Is there an adjustment within Windquake I have missed?

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