Following signals are taken via a same DB9 cable from LSC RFPD interface chassis.
All of these signals go through whitening filter now.
- K1:ALS-X_ARM_REFL_OUT_DQ
- K1:ALS-Y_ARM_REFL_OUT_DQ
- K1:LSC-POP_PDA1_DC_OUT_DQ
- K1:LSC-POP_PDA2_DC_OUT_DQ
In this time, our purpose is to increase a gain of the green-x signal.
For other signals, we only compared spectra before and after inserting whitening filter chassis
and there was no strange behavior.
For the green-x signal, several configuration of whitening gain and filters were checked.
With no whitening gain and filters, noise is limited by ADC noise level.
(ADC noise leve: 3e-6 [V/rHz] * 610e-6 [V/ct] * 2.3e-4 [?/? coming from foton] = 1.1e-6 [?/rHz])
Finally, we set 12dB gain and one zero/pole stage as the settings which circuit noise is beginning to be visible.
