this plot shows the comparison of PR2 & PR3 w/ oplevs on/off. There are problems...

1. The PR2 & PR3 loops are suppressing the error signals below the level of the sensor noise (which seems to have a 1/f noise of ~5 nrad/rHz @ 1 Hz). i.e these loops are injecting noise in the 1-10 Hz band.
2. The PR2 Yaw loop is making 20 dB of gain peaking at 5 Hz.
3. There is a lot of acoustic noise. We need more serious low pass filters for the 30-100 Hz band. There is not much BBH SNR below 30 Hz, so lets not worry about 10-30 Hz for now.