After Sheila saw some excess angular motion caused by the length drive, I tried improving the decoupling of EX and EY UIM.
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We took a swept sine measurement of Length to Pitch as well as Length to Yaw on friday night, driving through L1_LOCK_L_EXC, monitoring the oplevs, without any decoupling filters engaged. The measurements are saved as 2014-05-05_H1SUSETMX_L1L2PY_SweptSine.xml under SusSVN/sus/trunk/QUAD/H1/{ETMX/ETMY}/SAGL1/Data
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Those measurements were used to make a new fit, with a better resolution of Qs and phase than previous filters. See both pdfs for the fits of L2P w new measurement, P2P w old measurement and the ratio L2P/P2P
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The old filters were moved in FM6 for ETMX and FM6/FM7 for ETMY. They are called L2Plegacy
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A measurement was taken to test the L2P decoupling on EX, cf attached screenshot EX_UIM_decoupling. Even though the fit is pretty good, we only see 10dB attenuation in the .5Hz region (green w decoupling filters vs red without). Keita advised to tweak the overall gain.
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By doing quick tests its unclear if L2Y is providing anything good. I left the drivealign UIM input switches off for now. Will do more investigation tomorrow.