Summary

From klog22513, we can say IX MN Pitch control produces large noise (Fig1).
Then, I updated that control (Detail is shown in botom of this log).

Feedback signal changed Fig2 → Fig3 before/after control update (Red line shows ITMX P / Blue line is for IY P, which was relatively noisy, and is shown for comparison.)

Moreover, I have confirmed that OBSERVATION mode lasts a long time (Fig4).
► It lasted more than 40 mins (The reason it is out of OBSERVATION mode is because I deliberately requested LOCK_ACQUISITION.).

After that, I tried to do control noise projection for IX MN P, but I couldnt lock FPMI with the message "REFL HWP angle is not nominal value." (Fig5).
I dont know much about this, so I have decided to check tomorrow to see how much the control noise has been reduced.

Control Update

1. Notch around 7.3 Hz was too deep, so it was made shallower (30 dB to 20 dB).

2. Made OBS filter (ITMX MN OLDAMP FILTERS FM2).
    ► I Applied 4-oder eliptic filter from 0.4 Hz.
    ► Notches were put in against the peaks (around 0.61 Hz, 0.72 Hz, 0.98 Hz).
    ► Control was chaged as shown in Fig6 → Fig7 (UGF is now 0.19 Hz).

3. Guardian update (to request OBS filter ON).
    ► I added 'MN_OLDAMP_P':(['FM2'], True), to ITMX 'ENGAGE_LOWNOISE_CTRL' part in NEW_paramsA.py.

Memo

Next step

Check control noise of IX MN P
► Measure TF (CAL-CS_PROC_DARM_DISPLACEMENT_DQ / ITMX_MN_SUMOUT_P_OUT) and Spectrum of feedback signals.
► Calculate noise projection.

Check IX Y and EY P&Y control