M. Todd, C. Cahillane, S. Dwyer
I ran another estimate of the PRG, following Craig's method in alog 58327, and estimate it to be around 54.2 W/W.
I compared the TRX power to Input Power ratio during the FIND_IR state versus the PREP_ASC_FOR_FULL_IFO state, with the PRM transmission as a normalization factor.
TRX_POWER_FULL_IFO / INPUT_POWER_FULL_IFO
PRG = -------------------------------------------------------------------------------------
TRX_POWER_FIND_IR / (Tp * INPUT_POWER_FIND_IR)
I've attached the quick script I've used for the interesed reader.
I reran this measurement during DARM_TO_DC_READOUT (GRD-ISC = 501, input power = 2W), comparing the input and TR-X powers during the previous FIND_IR state (GRD-ISC = 16, input power = 2W). And I got a post vent PRG of 55.6 W/W. (post-vent)
I reran this estimate for the same states, before the vent (FIND_IR = 1427488687, DARM_TO_DC_READOUT =1427490018) and got a PRG of 55.7 W/W. (pre-vent)
It's interesting that we estimate almost the exact same PRG pre and post vent, though we may be able to improve this post vent value (probably not drastically) with some ASC improvements. We wanted to get this estimate to just check that everything is in general order in HAM1 after the vent.
I think our PRG channel calibration needs updating. Matt's measurement agrees with mine: that the PRG is about 54 when we are at 2 W of power. However, at 2 W it is currently reading 60, which is wrong, possibly due to slightly less power on IM4 trans. I will add a correction factor in FM4 of our "LSC_PR_GAIN" bank, 55.6/59.8 = 0.93.
I checked what the PRG was according to the calibration channel H1:LSC-PR_GAIN_OUT16 during the same time that I used for my measurement of the post-vent PRG (1432694134) and it is off by roughly a factor of 8%.
The calibration channel reports a PRG of roughly 59.9; I've measured it to be 55.5. We may benefit from some re-calibration.
