PSN-L Email List Message
Subject: Which is which?
From: Brett Nordgren brett3nt@.............
Date: Fri, 11 Sep 2009 10:00:30 -0400
A few days ago, Dave Nelson in California was able to obtain the loan of a
Nanometrics Trillium Compact-120, a professional quality triaxial packed
into a can only slightly larger than a large geophone. Our plan is to
compare its output with the home-built Force Balance Vertical running
Soon after it was installed, California obliged with a nice 3.9 up the
coast which gave us a modest sized test signal containing some higher
frequency energy, which we could use to compare the two instruments. Both
instruments' outputs were filtered with a 20Hz 4-pole low pass and the
Trillium had a two pole high-pass added at 1/50Hz, in order to match the
50-second low frequency rolloff of the FBV, since its own rolloff was at
The results are shown at http://bnordgren.org/seismo/TvsFBV01.gif or the
somewhat larger http://bnordgren.org/seismo/TvsFBV01.jpg
Question: Which is the $7000 Trillium and which is the FBV built by Dave?
Watch our wiggles
or watch some very very good wiggles
Public Seismic Network Mailing List (PSN-L)
[ Top ]
[ Back ]
[ Home Page ]