Wiener Filtering was applied on the data collected from the X-arm during the time: GPS time-996380715 (Aug 02, 2011. 21:25:00. PDT) to GPS time-996382215 (Aug 02, 2011. 21:50:00. PDT) for a duration of 1500 seconds. During this time the X-arm was locked, we checked it by acquiring data from channel C1:LSC-TRX_OUT_DQ .
The seismometers were near the beam splitter (guralp2) and near MC2 (guralp1).
Target data was obtained from channel C1:LSC-XARM_IN1_DQ.
Following graphs were obtained after applying the Wiener filter:
1.Seismic data acquired from Guralp1 (X and Y) and Guralp2 (X and Y) 2.Seismic data acquired from Guralp2 X 3.Seismic data acquired from Guralp2 Y
These graphs were obtained with srate = 2048 (sample rate) and N = 20000 (order of the filter).
Graph 1 is the best because the black (residual) line is below the red (target) line for low frequencies since we used seismic data from 4 channels. Graph 3 is the worst because we used seismic data from only one Y channel (Y axis of Guralp2) that is less related with the X-arm mirrors' motion since they are oriented orthogonally.