hang.yu@LIGO.ORG - posted 11:54, Friday 13 July 2018 - last comment - 14:07, Friday 13 July 2018(42889)
ETMY M0 actuation L2A decoupling
We did the M0 stage L2A decoupling for ETMY (similar to what we did in LHO:42723 for EX). It was motivated by that we saw some excess coherence between ETMY (where DARM actuation went) and C/DHARD than ETMX with C/DHARD at the microseismic band (LHO:42751).
The result is attached. The pink (cyan) trace is the L2P (L2Y) coupling with the old l2a filters, and the red (blue) one is with the new l2a filters.
When designing the filter we focused on the microseismic band ~ 0.2 Hz. For pitch we should be able to reduce the actuation L2P by about a factor of 2, and for yaw we should be able to essentially eliminate the L2Y coupling.
Images attached to this report
Comments related to this report
I'm working with Hang to make the fitting code he used to produce these filters more accessible (read: backward compatible) to the control room machines, but for now I've pulled the DTT template he used to gather the transfer functions to make these L2A filters committed them here:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMY/Common/Data
2018-07-13_H1SUSETMY_M0_L2A_FilterDesign_M0LPY_2_L3PY.xml
And committed the raw transfer function exports and coherence in the same place:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMY/Common/Data
2018-07-13_H1SUSETMY_M0_L2A_FilterDesign_M0L_2_L3P_coh.txt
2018-07-13_H1SUSETMY_M0_L2A_FilterDesign_M0L_2_L3P_tf.txt
2018-07-13_H1SUSETMY_M0_L2A_FilterDesign_M0P_2_L3P_coh.txt
2018-07-13_H1SUSETMY_M0_L2A_FilterDesign_M0P_2_L3P_tf.txt
2018-07-13_H1SUSETMY_M0_L2A_FilterDesign_M0L_2_L3Y_coh.txt
2018-07-13_H1SUSETMY_M0_L2A_FilterDesign_M0L_2_L3Y_tf.txt
2018-07-13_H1SUSETMY_M0_L2A_FilterDesign_M0Y_2_L3Y_coh.txt
2018-07-13_H1SUSETMY_M0_L2A_FilterDesign_M0Y_2_L3Y_tf.txt
For the record, the transfer functions have been exported as FREQ MAG PHA(rad)