Robert, Anamaria

During PEM injections in the beginning of O2, we did HAM1 HEPI injections. It turns out that H1 has much less coupling than L1 (see alog), so it's interesting to take a closer look and compare the sites. A few interesting points:

1) The first three plots show the H1 injection in various relevant signals, as well as the budgeted contribution to DARM. It's very close below some 20 Hz, but not perfectly reproducing DARM like L1 does. Also, the CHARD P is seemingly less sensitive to HAM1 motion (the estimated ambients aren't identical - which is the case for L1).

2) HAM1 moves more at H1 than L1, so the contribution to DARM could be reduced further by a factor of a few if the HAM1 filtering is improved (Arnaud did this at LLO). I checked the filtering for both sites in the suspensions; the CHARD signals get sent to L2 with not much gaining, so we can directly compare the controls at higher frequencies. However, at LLO we offload to L1 and at LHO we offload to M0.

3) The overall DARM contribution from L1 HAM1 motion, presumably through CHARD, is a factor of 10 higher but, even worse, the coupling is almost a factor of 100 higher. I'm hoping that by looking at such comparisons we can figure out how to reduce the L1 coupling.