J. Kissel

Inspired by Jim W. who had the idea to take OSEM basis transfer functions (see Jim's prototype measurements in LHO aLOG 41227) 
to help diagnose the lingering problems with the H1SUSOPO (see previous latest in LHO aLOG 41196), 
Stuart grabbed his own OSEM basis TFs of the healthy L1SUSOPO (see LLO aLOG 38455). 

Since Stuart's had a little bit better SNR, I imported his templates and re-drove the H1 SUS OPO in the OSEM basis.

The results (alloposs_2018-04-02_SUSOPOS_OSEMBasis_ALL_TFs.pdf) were indeed very helpful: it immediately identified H3 as having an incorrect actuation sign. I subsequently flipped the COILOUTF gain (as though it were, say, an incorrect magnet polarity), and this cleaned up the problematic Transverse and Yaw transfer functions perfectly. There's still an overall sign issue with Transverse, but correcting that with an opposite damping loop gain means that all DOFs now have functional damping.

The OSEM basis also reveals that V2 OSEM has a remaining problem of some very strange frequency response. That manifests only in the V, and P TFs (looking at E1700390, we see that R involves very little V2). I believe this strangeness is mechanical or electronic, because it has *changed* since when we first started measuring the H1 SUS OPO -- compare the change between the 2018-02-27 and 2018-03-29 results. 

We'll keep chasing these daemons tomorrow (and gather damping loops closed TFs), but I'm happy to say that we've finally made some progress!!

The new H1 data has been committed here:
OSEM Basis, prior to H3 sign flip:
    /ligo/svncommon/SusSVN/sus/trunk/OPOS/H1/OPO/SAGM1/Data/
        2018-04-02_2000_H1SUSOPO_M1_WhiteNoise_H1_0p01to50Hz.xml
        2018-04-02_2000_H1SUSOPO_M1_WhiteNoise_H2_0p01to50Hz.xml
        2018-04-02_2000_H1SUSOPO_M1_WhiteNoise_H3_0p01to50Hz.xml
        2018-04-02_2000_H1SUSOPO_M1_WhiteNoise_V1_0p01to50Hz.xml
        2018-04-02_2000_H1SUSOPO_M1_WhiteNoise_V2_0p01to50Hz.xml
        2018-04-02_2000_H1SUSOPO_M1_WhiteNoise_V3_0p01to50Hz.xml

Euler Basis, After H3 sign flip:
    /ligo/svncommon/SusSVN/sus/trunk/OPOS/H1/OPO/SAGM1/Data/
        2018-04-02_2157_H1SUSOPO_M1_WhiteNoise_L_0p02to50Hz.xml
        2018-04-02_2157_H1SUSOPO_M1_WhiteNoise_P_0p02to50Hz.xml
        2018-04-02_2157_H1SUSOPO_M1_WhiteNoise_R_0p02to50Hz.xml
        2018-04-02_2157_H1SUSOPO_M1_WhiteNoise_T_0p02to50Hz.xml
        2018-04-02_2157_H1SUSOPO_M1_WhiteNoise_V_0p02to50Hz.xml
        2018-04-02_2157_H1SUSOPO_M1_WhiteNoise_Y_0p02to50Hz.xml


The crude analysis script for loading in, processing and comparing the OSEM basis TFs is here:
    /ligo/svncommon/SusSVN/sus/trunk/OPOS/Common/MatlabTools
        plotOPOS_dtttfs_OSEMBasis.m