[Dan-chen, Carl, Haoyu]

We measured the input jitter coupling to darm.  This measurement will serve 2 purposes:  1. Allow projection of input jitter measured in IMMT1 trans QPDs to be projected in to DARM for the noise budget. 2. Allow jitter noise coupling models to be refined.

We created Jitter noise by driving MCO.  This noise was witnessed by the IMMT1 trans QPDs.  MCO was driven with 500 counts in the test filter bank K1:VIS-MCO_TM_TEST_dof_EXC for all frequencies and dof.  The coherence around 100 Hz where jitter noise coupling is expected is enough for a reasonable noise projection.  The first attached figure shows the pitch transfer function measurement.  The second attached figure shows the yaw transfer function measurement (IMMT1 TRANS to DARM).  Anti-whitenning of 3 poles of 1Hz and 3 zeros at 100Hz and gain 1E-9 was applied in calibration to CAL-CS_PROC_DARM. 

We also (previously) drove IMMT1 suspension P to to DARM coupling.  This was done because we were affraid to drive MCO too hard.  It may be a useful measuremnt so it is included here in the 3rd attachment.  The drive amplitude was 2000 counts at all frequencies in the SUMOUT filter bank.  Note the large differences in coherence between DARM and OMC channels.  Also Oplev is less coherent after 100Hz however we use it here as it is in urad units.