J. Kissel

More details to come after I'm able to measure H1SUSOPO again, but as a result of LLO converting to the standard SUS basis (LLO aLOG 38272). and remeasuring their OPOS TFs (LLO aLOG 38308), I've made a comparison between LLO** and LHO's data again and thinks look far more consistent. I've also updated the dynamical model after the (yet to be documented) work Alvaro and I have done during the LVC meeting. In summary, we added several more elements to the stiffness matrix that explain the cross-coupling visible in a lot of the degrees of freedom.

(**Note, the confusion Stuart mentions regarding scale factors was that he didn't remove the special calibration conversion that accounted for the modified HAM-A driver, and the bad units in PRY lever arm basis change when processing the data with 
/ligo/svncommon/SusSVN/sus/trunk/OPOS/Common/MatlabTools/plotOPOS_dtttfs_M1.m. I've fixed and commited the script removing the special LLO case, and now both observatories are calibrated with the same scale factor. I've also re-processed and committed the LLO data.)

Check out the new results attached. The notable differences are in the DOFs that I've not been able to close damping loops: T and Y. T appears to somehow have a sign flip from LLO and expected. Remember we're now using exactly the same basis change matrices. The only difference in the digital system is the magnet compensation signs in the COILOUTF banks, which we believe are correctly compensating the as-built configurations. But, this is to be investigated further. For Y, it looks like the phase at high frequency is asymptoting to a different value. No idea what's going on there.

However, because the results from other DOFs are so similar, I copied over the damping loop design from LLO aLOG 38309, and tried things out. L, V, R, and P are just as successful as LLO. Nice!

Now to still figure out what's going on with T and Y...

I've started the investigation by taking (loops open) T and Y TFs with the L V P and R loops closed, hoping that it might clean things up a bit. The Qs look quite different from the 2018-03-16 measurements, but I ran out of time to investigate further. More tomorrow...