We installed the 6 Mhz preamplifier for the Bs_IMC_D1Y_DCHF signal, and
connected its output via a 7.2 m long cable to the laser lab Pr crate
demodulator input. We then checked the Sc_IB_FmodErr signal by changing the
modulation frequency by +/- 450 Hz in regular steps (10 or 20 Hz every 10
seconds); we repeated this procedure for different demodulation phases,
until we obtained a symmetric FmodErr-vs-frequency response around zero.
The frequency sweeps are shown in the plots; a 10 Hz per 10 sec. sweep at
-83 degrees, and several sweeps with phases -128, -108, -118, -115 degrees
(20 Hz every 10 sec). All sweeps were performed with an 1111 Hz amplitude of
0.3 (instead of 0.03), for having a better signal-to-noise ratio. The best
symmetry is obtained at -115 degrees, which is thus the good demodulation
phase. The old calibration factor (8100) was updated to -10368 for having
again a calibration in Hz.
Presently, the modulation frequency seems to be too high by 15-20 Hz.
The good parameter settings are: -115 degrees in Lo30, and -10368 in the
FmodErr probe line in contIB.
Details:
--------
At 832071118 increase 1111 Hz amplitude from 0.03 to 0.3.
At 832071548 stepped up the mod. frequency by 3x10 Hz (from 6264287 Hz)
At 832071772 stepped down 30 Hz. At 832071806, back to 0.3 Hz.
832072841 amplitude 0.3.
832073057 set to 6264437 Hz
832073130 decrease by step of 10 Hz every 10sec
832073557 ulocked at 4007Hz
demodulation phase at -83 degres
832073933 back to 6264237 Hz by error (instead of 62644287 Hz)
832074008 back to 0.03 gain
832082644 go to 62644027 Hz set demodulation phase to -128 degres
832082696 increase by step of 20Hz every 10 sec
832082968 unlocked at 62644546 Hz
832083081 demodulation phase to -108 degres
832083117 go to 62644027 Hz and increase by step of 20Hz every 10 sec
832083410 stop at 62644526 Hz
832083474 go to 62644027 Hz set demodulation phase to -118 degres
832083511 increase by step of 20Hz every 10 sec
832083764 stop at 62644527 Hz
832083805 set demodulation phase to -115 degres
832083865 go to 62644027 Hz and increase by step of 20Hz every 10 sec
832084123 stop at 62644527 Hz
dynamic calibration
832084199 go to 62644207Hz
832084287 go to 62644367 Hz
832084341 back to 62644287 Hz
actual calibration factor: 8100
correction: -160/125=1.28
new calibration fact -10368
832084874 lock, unlock transitions
