This coherence check was done between PR/BS oplev singal and AA diagonalized signal. Note that there is no excitation sent to PR/BS, but the PR/BS local control loop was closed.

Note: blue curves are PR/BS local control open, red curves are PR/BS local control closed.

We could see a strong coherence between PR pitch/yaw oplev signal and AA.

Therefore, the PR local control seems to be introducing noise in pitch/yaw from 10 to several tens of Hz.