PSN-L Email List Message

Subject: N.Calif event
From: barry lotz gbl@.......
Date: Thu, 16 Mar 2000 19:44:19 -0800

    I've uploaded a new event file for a small vertical "strong motion"
accelerometer. I'm not to familiar with acceleration recording accept
that I realize the frequency content is a higher. I increased my sample
rate for the Lehman and this sensor to 50 hz. I was surprised to get
little long period content in this  recording. Is this common for
accelerations? I am using a Vrdt at the end of a  ~ 6" long beam with a
phosphor bronze hinge at the support( natural freq is about 25 hz). I
have a 4" speaker coil/magnet feedback to provide some damping. Is it
possible the feedback is too strong ie damping to high and therefore my
long period waves are truncated? The "official tap" test shows about a
two cycle response before stopping so the damping appears to be
reasonable.Though I highpassed the signal @ 0.5 hz there wasn't much


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