J. Kissel, S. Ballmer

Upon receiving a review from Stefan, who agrees that I've interpretted his methods correctly to arrive at the proposed change to the OMC DCPD SUM and NULL balance matrix in yesterday's LHO:68360, I have now installed that 2024-04-03 proposal for the OMC DCPD balance matrix from that aLOG,
    MM_proposed =
          0.99455       1.0055
          0.98259      -1.0177


via the command line,
    $ caput H1:OMC-DCPD_MATRIX_1_1 0.99455; caput H1:OMC-DCPD_MATRIX_1_2 1.0055; caput H1:OMC-DCPD_MATRIX_2_1 0.98259; caput H1:OMC-DCPD_MATRIX_2_2 -1.0177
    Old : H1:OMC-DCPD_MATRIX_1_1         1.01039
    New : H1:OMC-DCPD_MATRIX_1_1         0.99455
    Old : H1:OMC-DCPD_MATRIX_1_2         0.98961
    New : H1:OMC-DCPD_MATRIX_1_2         1.0055
    Old : H1:OMC-DCPD_MATRIX_2_1         0.98961
    New : H1:OMC-DCPD_MATRIX_2_1         0.98259
    Old : H1:OMC-DCPD_MATRIX_2_2         -1.01039
    New : H1:OMC-DCPD_MATRIX_2_2         -1.0177

    Checking the answer...
    $ caget H1:OMC-DCPD_MATRIX_1_1 H1:OMC-DCPD_MATRIX_1_2 H1:OMC-DCPD_MATRIX_2_1 H1:OMC-DCPD_MATRIX_2_2 
    H1:OMC-DCPD_MATRIX_1_1         0.99455
    H1:OMC-DCPD_MATRIX_1_2         1.0055
    H1:OMC-DCPD_MATRIX_2_1         0.98259
    H1:OMC-DCPD_MATRIX_2_2         -1.0177

Attached are screenshots of the new values within the MEDM screen, and the acceptance of these values in both the safe.snap and OBSERVE.snap files.

A note (just because MEDM matrices can be confusing):
    ( SUM )   ( DCPDA_1_1   DCPDB_1_2 ) ( DCPDA )
    (     ) = (                       ) (       ) 
    ( NULL)   ( DCPDA_2_1   DCPDB_2_2 ) ( DCPDB )

or
    SUM  = DCPDA_1_1 * DCPDA + DCPDB_1_2 * DCPDB
         = 0.99455 * DCPDA + 1.0055 * DCPDB

    NULL = DCPDA_2_1 * DCPDA + DCPDB_2_2 * DCPDB
         = 0.98259 * DCPDA - 1.0177 * DCPDB

This means, for the SUM, which eventually becomes DARM_ERR, the coefficients that form the SUM have changed by 
    :: (0.99455 - 1.01039)/ 0.99455 = -0.0159 = -1.6% for DCPDA and 
    :: (1.0055 - 0.98961)/ 1.0055 = +0.0158 = +1.6% for DCPDB
which I think we can safely attribute all changes in the balance to be due to the changes in the DCPD readout electronics (since this matrix hasn't been updated since O3, prior to the replacement/upgrade of the transimpedance amplifier, the whitening chassis, the [lack of] anti-aliasing chassis, and the new ADC.).