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Entry  Tue Oct 25 20:04:40 2011, Mirko, Update, Adaptive Filtering, Adaptive filter witness and EP SNR MC-F_SNR_to_Dark_noise.pngCoherence.png
    Reply  Tue Oct 25 21:49:13 2011, Den, Update, Adaptive Filtering, Adaptive filter witness and EP SNR gur1_x.jpggur1_y.jpggur1_z.jpg
    Reply  Tue Nov 1 18:16:50 2011, Den, Update, Adaptive Filtering, Adaptive filter witness and EP SNR translation_length.jpgtrans_tilt.jpgseismic_length.jpgfiltering.jpgtilt_filtering.jpg
Message ID: 5738     Entry time: Tue Oct 25 20:04:40 2011     Reply to this: 5740   5777
Author: Mirko 
Type: Update 
Category: Adaptive Filtering 
Subject: Adaptive filter witness and EP SNR 

We currently have the code running for all DOFs using all witness channels. By default nothing is applied. C-Code parameters can be changed via the respective EPICS variables. Sanity checks in the C-Code make sure the code doesn't crash when nothing / zeros are fed to the code. Let's look into applying FF to one DOF only as a starting point. We start with MCL.

Remember there are two possible signals to look into MC-F and MC-Servo. See page 5695 http://nodus.ligo.caltech.edu:8080/40m/5695

Dark noise: MC-F over MC-Servo which is unconnected in this measurement:
MC-F_SNR_to_Dark_noise.png

=> At least 20dB SNR. ADC noise should not be an issue. Of course more is always better.

Coherence of seismometers to MCL:


STS1 is located at the vertex. x-axis along the x arm.
GUR1 is located at the IMC MC2 mirror. Same orientation.
Coherence.png

=> 1. Only the x-direction has good coherence (to be expected)
     2. Only good coherence at 1.5-4Hz (huh?)

So probably other noise sources are dominating. Let's look into noise projections. Remember IMC autoalignment is off.

A quick adaptive filter run with only the GUR1 and STS1 witnesses applied only to MCL didn't really do anything. Some more thought needs to be invested into the AA and shaping filters.

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