PSN-L Email List Message

Subject: Which is which?
From: Brett Nordgren brett3nt@.............
Date: Fri, 11 Sep 2009 10:00:30 -0400

Hi All,

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 
beside it.

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 
120 seconds.

The results are shown at  or the 
somewhat larger

Question:  Which is the $7000 Trillium and which is the FBV built by Dave?

Brett .

Watch our wiggles

or watch some very very good wiggles


Public Seismic Network Mailing List (PSN-L)

[ Top ] [ Back ] [ Home Page ]