Jeff, Oli

Took damped health check transfer functions for the RMs to compare how the damping has changed before vs after the vent/uninstall+reinstall/cable switching/etc.

Here are the measurements I took:

RM1:

Data: /ligo/svncommon/SusSVN/sus/trunk/HTTS/H1/RM1/SAGM1/Data/2025-05-27_1700_H1SUSRM1_M1_WhiteNoise_{L,P,Y}_0p01to50Hz.xml, r12333

Comparison: /ligo/svncommon/SusSVN/sus/trunk/HTTS/Common/Data/allhttss_2022_vs_2025_DampingOn_H1SUSRM1_ALL_TFs.pdf*, r12342

RM2:

Data: /ligo/svncommon/SusSVN/sus/trunk/HTTS/H1/RM2/SAGM1/Data/2025-05-27_1715_H1SUSRM2_M1_WhiteNoise_{L,P,Y}_0p01to50Hz.xml, r12334

Comparison: /ligo/svncommon/SusSVN/sus/trunk/HTTS/Common/Data/allhttss_2022_vs_2025_DampingOn_H1SUSRM2_ALL_TFs.pdf*, r12342

You can see for both RM1 and RM2, the resulting bumps in the old traces have now been replaced with small troughs at those same frequencies, and there are small bumps on either side. This is because the cross coupling has changed, so there is over-damping at the peak frequencies, creating gain peaking (new bumps around the peak frequencies) (84585). To get rid of this we are lowering the gain in the damping filters.

* The phases for the latest (2025-05-27) measurements have been shifted by 180degrees.