Stefan, Elli

On Saturday Stefan measured the AS36 signals with dither lines from the BS and SRM (alog 20777):

Lines:
H1:SUS-SRM_M3_ISCINF_P_EXC 7.0Hz, 300cts
H1:SUS-SRM_M3_ISCINF_Y_EXC 7.5Hz, 900cts
H1:SUS-BS_M3_ISCINF_P_EXC  8.0Hz, 100cts
H1:SUS-BS_M3_ISCINF_Y_EXC  8.5Hz,  30cts

Here are some plots of the AS36 signals demodulated against these line frequencies.  These signals  show how the sensitivy of the AS_36 WFS to the BS and SRM, which changes during the heat-up stage of the whole interferometer, and during 45MHz modulation depth reduction.  Attached are plots of the original and demodulated signals vs time.  Two vertical red lines are plotted; the first corresponds with when the IFO reaches full power, the second is when the 45MHz modulation depth reduction begins.  At the end of the time series the traces go crazy-  this is where Stefan reports lock was lost due to SRC1 yaw run away.

The following WFS channels are fed back to the optics at this point:
AS_B_RF36_I_PIT      >>   SRC1 PIT      (seen in demodulation of 7.0Hz line. Right two plots, red trace)
AS_B_RF36_I_YAW   >>   SRC1 YAW    (7.5 Hz line.  Right two plots, blue trace)
AS_A_RF36_I_PIT      >>   MICH PIT       (8 Hz line. Left two plots, red trace)
AS_B_RF36_Q_YAW  >>  MICH YAW    (8.5Hz line.  Right two plots, brown trace)

The SRC1 PIT signal doesn't change much, which is good.  SRC1 YAW has a 180deg ohase change during the heat-up stage.  Lines 1813 and 1815 of the guardian indicate a sign change in the ASC input matrix, maybe this corresponds to this phase change (?).  MICH PIT signal looks pretty good, getting close to 180deg phase at the end of the modulation depth reduction.  MICH YAW drifts downwards in phase, it looks like it hit -180deg just at the point we lost lock.