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Entry  Fri Jun 10 20:11:46 2022, yuta, Update, ASC, Yarm ASS re-tuning in progress Screenshot_2022-06-10_20-10-52.png
    Reply  Mon Jun 13 20:26:09 2022, yuta, Update, ASC, Yarm ASS re-tuning in progress -part 2- Screenshot_2022-06-13_20-47-12.pngScreenshot_2022-06-13_20-44-43.png
       Reply  Tue Jun 14 20:57:15 2022, Anchal, Update, ASC, Yarm ASS working now 
Message ID: 16909     Entry time: Fri Jun 10 20:11:46 2022     Reply to this: 16911
Author: yuta 
Type: Update 
Category: ASC 
Subject: Yarm ASS re-tuning in progress 

[Anchal, Yuta]

We tried to re-tune Yarm ASS today. It cannot be fully closed as of now. I think we need to play with signs.

Motivation:
 - We want to make sure Yarm ASS work with current ITMY coil matrix (40m/16899).
 - ASS makes the beam positions on test masses to be the same every day.

What we did:
 - Adjusted A2L paths of C1:ASS-YARM_OUT_MTRX based on cavity geometry. For the paths to maximize the transmission using TT1 and TT2, we just assumed they are correctly calculated by someone in the past.
 - Adjusted OSC_CLKGAINs so that ITMY and ETMY will be shaken in the same amplitude in terms of radians. The ratio of the excitation was determined to take into account for the oscillator frequency difference between DOFs.
 - Checked the time constant of A2L paths by turning on A2L paths only, and checked that of max-transmission paths by turining on them only.
 - Adjusted DEMOD_SIG_GAINs so that their time constants will be roughly the same, with C1:ASS-YARM_SEN_MTRX fully identity matrix and all servo GAINs to be +1.
 - Re-tuned DEMOD_PHASEs to minimize Q signal. C1:ASS-YARM_ITM_PIT_L_DEMOD_PHASE and C1:ASS-YARM_ITM_YAW_T_DEMOD_PHASE were re-tuned within +/- 5 deg.
 - These changes are recorded in /opt/rtcds/caltech/c1/Git/40m/scripts/ASS/ASS_DITHER_ON.snap now.

Result:
 - A2L loops seems to be working, but max-transmission paths seems to diverge at some point. I think we need to play with the signs/gains of max-transmission paths for C1:ASS-YARM_OUT_MTRX.
 - Attached is the current configuration we achieved so far.

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