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Entry  Wed Mar 5 11:33:10 2014, Koji, Summary, LSC, 2 arm ALS->LSC transition - road map 
    Reply  Wed Mar 5 19:15:39 2014, Jenne, Summary, LSC, ALS offset moving script modified 
    Reply  Wed Mar 5 22:32:21 2014, manasa, Update, LSC, Stuck at step 2 
       Reply  Thu Mar 6 11:15:32 2014, Koji, Summary, LSC, Stuck at step 2 
    Reply  Fri Mar 7 00:43:34 2014, manasa, Update, LSC, ALS C&D locked (on MC2 and ETMs) and IR resonance obtained ALS_MC2CARM.pdf
Message ID: 9694     Entry time: Wed Mar 5 19:15:39 2014     In reply to: 9691
Author: Jenne 
Type: Summary 
Category: LSC 
Subject: ALS offset moving script modified 

Quote:

- Step 3: Transition from ALS Common to 1/SQRT(TRX)+1/SQRT(TRY). Make sure that the calibration of TRX and TRY are matched.
  The current understanding is that the offset for 1/SQRT(TRX)+1/SQRT(TRY) can't be provided at the servo filter. Figure out
  what is the correct way to give the offsets to the TR signals.

 I have modified the script ALSchangeOffsets.py (in ..../scripts/ALS/) to also handle a "CARM" situation.  There is a new button for this on the ALS in LSC screen.  This script takes the desired offset, and puts half in the ALSX offset, and half in the ALSY offset.  Whatever offset you ask for is given the sign of the input matrix element in the ALS->CARM row of the input matrix.  For example, if you ask for a CARM offset of 1, and the matrix elements are ALSX->CARM=+1 and ALSY->CARM=-1 (because your beatnotes are on opposite sides of the PSL), you will get an offset of +0.5 in ALSX and -0.5 in ALSY, which should be a pure CARM offset. The offsets get set as expected, but I haven't had a chance to test it live while the arms are locked. 

I also want to write a script that will average the IN1 of the 1/sqrt(TR) signals, and put that number into the 1/sqrt(TR) offsets.  If this is run when we are at about half fringe, this will set the zero point of the 1/sqrt(TR) signals to the half fringe (or where ever we are).  Then, we need a script similar to the ALS CARM one, to put offsets into the CARM combination of 1/sqrt(TR)s. 

I think that putting the offsets in before the servo filters will mean that the signals coming out of the input matrices will already be at their zero points, so we won't have as much trouble shifting from ALS to IR.

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