S. Koehlenbeck, B. Lantz [posted by J. Kissel]

We're looking at the results posted by Jeff in LHO:91990, and are suspicious of the new ISI-DIFF channels. Here, Sina compares various available versions of the HAM2 table motion, 

    (1) H1:ISI-HAM2_BLND_CPSX_IN1_DQ      capacitive position sensor, pre-blend
    
    (2) H1:ISI-HAM2_CAL_CART_X_OUT_DQ     GS13s, pre-blend, but calibrated already into displacement units 
  
    (3) H1:ISI-DIFF_H2_BLND_SS_X_DQ       blended CPS + GS13s, re-constructed in seiproc for the input to the DIFF channel

    (4) H1:ISI-HAM2_ISO_X_IN1_DQ          blended CPS + GS13s, in loop in the HAM2 feedback. Contains loop suppression

    (5) H1:ISI-HAM2_ISO_X_OUT             feedback control signal

    (6) H1:ISI-DIFF_H23_SS_X_OUT_DQ       differential HAM3 - HAM2, using the HAM2 blended CPS+GS13 reconstructed in seiproc (3).

The message -- where we use the pre-blended sum of (1) and (2), it should look identical to (4) the reconstructed HAM2 super sensor, but it does not.
Or, the GREEN trace is a factor of ~2x larger that RED below 0.2 Hz, and BLUE above 0.2 Hz.

The discussion and investigation continues...