Noise determination STS2 vs -ESP SN 3771

Introduction

As part of the operation of the Saint Louis University broadband seismic network, all sensors received for the network are evaluated for noise performance at the SLm station on the university campus. The procedure follows the paper A direct method for caluclating instrument noise levels in side-by-side seismometer evaluations by L. Gary Holcomb of the USGS (USGS Open-File Report 89-214)./

The operational testing requires a comparison of two data streams from different sensors. We accomplish this by using a 6 channel Quanterra Q-680 data acquisition systems. The SLM H channel is an STS-2 seismometer. The L channel is used for the sensor to be tested.

This page presents the results for Day 091 2005 and a direct comparison of the STS-2 to CMG3-ESP SN 3771 L channel). because of low teleseismic activity. 17 data segments are usually taken hourly starting at 0000 through 1700. 8192 time samples are used (~90 sec for 20 sps data stream) and 8192 sec for the 1 sps data stream. The noise results from the 20Hz and 1Hz data streams overlap at a 10 second period.


Noise test Z component of CMG3-ESP 3771 vs STS-2. The Blue dots are the estimates of ground noise. The red dots are the estimate of the instrument self noise. The black curves are the Albuquerque low and high noise models. Left: STS-2, Center: CMG3-ESP 3771 , Right: Coherency


Noise test N component of CMG3-ESP 3771 vs STS-2. The Blue dots are the estimates of ground noise. The red dots are the estimate of the instrument self noise. The black curves are the Albuquerque low and high noise models. Left: STS-2, Center: CMG3-ESP 3771 , Right: Coherency


Noise test E component of CMG3-ESP 3771 vs STS-2. The Blue dots are the estimates of ground noise. The red dots are the estimate of the instrument self noise. The black curves are the Albuquerque low and high noise models. Left: STS-2, Center: CMG3-ESP 3771 , Right: Coherency