Now that both sites are running the 70 W, I've done a quick comparison of the periscope motion and the microphones.
The plot shows PSL periscope accelerometer (top) and mic (bottom) at LLO and LHO. LHO periscope has significantly more motion 20 - 300 Hz and around 1 kHz, though from Jenne's recent look at WFS, looks like the peaks at 350 Hz (PZT mount) and ~600 Hz are what get in as jitter. I recently did a make-up air test at LLO; there's no effect on the per acc at LLO but maybe LHO should do a quick on/off check to see if it couples in at LHO.
The orange lines in the plots show from a day before red, before Peter and Jeff did some noise reduction work, so you can see the improvement orange to red, especially at high freq.
As for microphones, it looks like LHO's is sensor limited and heavily polluted by 60 Hz. PEM runs differential, so maybe something along the way is getting onto the shield? We see this in many of the mics there. Note that LLO has different microphones that have lower sensor noise, but not enough to account for the difference we see now between the sites (the microphone-type difference is included in the calibration).
I took LHO data during the middle of the night 4/24 and 4/25; I'm told the PSL was in science mode and both sites have HAM6 clean rooms running.
The floor motions are very different at the two sites at the moment, looking at the closest floor accelerometers, under HAM1. So some of the extra motion at the periscope might be explained by this (calibration is the same for these two channels, so they are directly comparable).
Cheryl, Terra
Last week Cheryl turned the PSL makeup air to a few different levels. I've looked at the PSL periscope acc and the microphone (though as previously mentioned, not sure how much info can be gleamed from the mic). LHO PSL makeup air runs at 20% for science mode; Cheryl also tried 10% and 40%. Results show no impact on periscope motion save for slight increase just under 10 Hz - nothing to explain the large difference between the sites' pericope motion at high frequency. LLO makeup air test here.
