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Entry  Fri Apr 18 20:17:17 2014, Jenne, Update, LSC, ALS noisy ALS_1kHzRMSnoise.pdfALS_oolNoise.pdf
    Reply  Mon Apr 21 22:53:16 2014, manasa, Update, LSC, ALS noise ALSX_FreeInLoop.jpgALSXY_inLoop.jpg
       Reply  Tue Apr 22 01:11:42 2014, Jenne, Update, LSC, TRY 60Hz noise TRY_60Hz_noise_21Apr2014.pdf
          Reply  Tue Apr 22 21:54:50 2014, manasa, Update, LSC, TRY 60Hz noise 60HzTRY.jpg
             Reply  Tue Apr 22 22:49:10 2014, rana, Update, LSC, TRY 60Hz noise 
                Reply  Wed Apr 23 19:58:00 2014, manasa, Update, LSC, TRY 60Hz noise 
                   Reply  Tue May 6 18:32:14 2014, steve, Update, LSC, TRY 60Hz noise hunt ETMY-ISCT_EISOL.jpg
                      Reply  Wed May 7 14:01:36 2014, steve, Update, LSC, TRY 60Hz noise hunt 
                         Reply  Thu May 8 17:25:17 2014, steve, Update, LSC, TRY 60Hz noise hunt 
                         Reply  Fri May 16 16:08:12 2014, steve, Update, LSC, Isolating base plates ISObaseplates.jpg
                Reply  Wed Apr 23 23:48:30 2014, manasa, Update, LSC, Y end whitening board IMG_1378.JPGIMG_1379.JPGIMG_1378.JPG
                   Reply  Thu Apr 24 14:23:09 2014, not manasa, Update, LSC, Y end whitening board 
                      Reply  Thu Apr 24 23:55:31 2014, Koji, Update, LSC, Y end whitening board P4245550.JPG
                         Reply  Fri Apr 25 10:43:57 2014, Koji, Update, LSC, (Fixed) Y end whitening board D990399-B_40m.pdfP4245552.JPGP4245553.JPGP4245551.JPG
                            Reply  Thu Dec 11 18:12:46 2014, ericq, Update, LSC, (Fixed) Y end whitening board 
                               Reply  Thu Dec 11 22:44:23 2014, rana, Update, LSC, QPD screens 
          Reply  Thu Apr 24 00:11:35 2014, Jenne, Update, LSC, Yend shutter back. 
       Reply  Sun Apr 27 20:26:19 2014, Koji, Update, LSC, Phase Tracker servo characterization ALSX_PTTF.pdfALSY_PTTF.pdf
          Reply  Sun Apr 27 21:30:59 2014, Koji, Update, LSC, ALS servo characterization ALSX_OLTF.pdfALSY_OLTF.pdf
             Reply  Mon Apr 28 10:24:10 2014, Koji, Update, LSC, error signal characterization ALSX_SPE.pdfALSY_SPE.pdf
                Reply  Mon Apr 28 10:34:51 2014, Koji, Update, LSC, new ALS servo design ALSX_OLTF_new2.pdfALSY_OLTF_new2.pdf
                   Reply  Mon Apr 28 10:48:48 2014, Koji, Update, LSC, new ALS servo design: comparison ALSX_OLTF_new.pdfALSY_OLTF_new.pdf
                      Reply  Mon Apr 28 10:59:54 2014, Koji, Update, LSC, New ALS servo design: expected error signals ALSX_SPE_new.pdfALSY_SPE_new.pdf
                         Reply  Mon Apr 28 11:08:11 2014, Koji, Update, LSC, New ALS servo design: expected error signals 140421_ALS_servo.zip
Message ID: 10785     Entry time: Thu Dec 11 18:12:46 2014     In reply to: 9854     Reply to this: 10786
Author: ericq 
Type: Update 
Category: LSC 
Subject: (Fixed) Y end whitening board 

Quote:

Gain mystery

- It was not sure how the whitening gains have been given.

- The corresponding database entry was found in /cvs/cds/caltech/target/c1auxey/ETMYaux.db as

grecord(ao,"C1:ASC-QPDY_S1WhiteGain")
grecord(ao,"C1:ASC-QPDY_S2WhiteGain")
grecord(ao,"C1:ASC-QPDY_S3WhiteGain")
grecord(ao,"C1:ASC-QPDY_S4WhiteGain")

- The gains for S2-S4 were set to be 30. However, C1:ASC-QPDY_S1WhiteGain was set to be 8.62068.
And it was not writable.

- After some investigation, it was found that the database was wrong. The DAC channel was changed from S100 to S0.
The corrected entry is shown here.

grecord(ao,"C1:ASC-QPDY_S1WhiteGain")
{
        field(DESC,"Whitening gain for QPDY Seg 1")
        field(DTYP,"VMIVME-4116")
        field(OUT,"#C0 S0 @")
        field(PREC,"1")
        field(EGUF,"42")
        field(EGUL,"-22")
        field(EGU,"dB")
        field(LINR,"LINEAR")
        field(DRVH,"30")
        field(DRVL,"-10")
        field(HOPR,"30")
        field(LOPR,"-10")
}

- Once c1auxey was rebooted, the S1 whitening gain became writable. Now all of the channels were set to be +30dB (max). 

This exact situation was happening at ETMX. I did the exact same change to the database, now I can read and write all four gain segments.

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