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Subject: Multi-Dimensional-Sensor, First Time Of Arrival Only
From: "Geoffrey" gmvoeth@...........
Date: Wed, 27 Jun 2007 02:31:57 -0700

I was just wondering if you connected a strain guage or
other sensor type unknown to me where the vertical pendumlum
wire joins at the upper support if you could possibly
measure weight changes that might result from motion in any
of the three axises ? The point here is to look only at first time of arrival
of the various phases and not worry about direction in any one plane.

I am unable to experiment with thesse ideas but i imagine
I can not imagine anything that has not already been
tried elsewhere before.

Can someone more knowledgeable please give me more ideas along this line.

The sensor would be the single most critical component in this system
and not the other hardware.

It seems to me the only damping you would need is of the horizontal pendulum motion.

When I experimented many years ago with a XY single horizontal only pendulum
I had quite good results with first time of arrivals but since I was only interested
actually in the vertical I did not look at it any closer. I could not tell the other fancy
data the rest of you are looking for like NS or EW motion just that there was
motion at this point in time.

At that time I was under instruction by a geophysicist at Golden on how to
read seismic waves and all
he wanted to see, ever, was first time of arrivals of the vertical waves
regardless of the other features.

In this modern day there must be a decent strain guage with the necessary
sensitivity etc...usw... to take an 8 lb pendulum or so.



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