louis.dartez@LIGO.ORG - posted 13:25, Tuesday 17 September 2024 - last comment - 14:30, Tuesday 17 September 2024(80141)
Engaged new COILOUTF filter gains for 32bit DACs on ETMX
The IFO was kicked back to DOWN while approaching CHECK_VIOLINS_BEFORE_POWERUP during the fire alarm. I kept the IFO in DOWN for a moment while I engaged the filter modules with the 32bitDAC gains mentioned in LHO:80017. screenshots attached.
Images attached to this report
Comments related to this report
i saved the filter module changes in SDF. we'll need to revert if we end up swapping the DAC's back out
It turns out that the new LIGODACs were only put in place for L3, not L1-L3. I've reverted my FM changes to L1 and L2. Furthermore, Marc explained to me that the new 32 bit DACs are effectively 28 bit DACs so I've adjusted the gains in the L3 ESDOUTF filters to 2**10 from 2**14.
Images attached to this comment
From discussion with Marc, it turns out that according to LHO:80023 there is a gain of 275.31 being applied to the output of the L3 LIGODACs. This gain accounts for the difference between the 20bit DACs and the new LIGO-DAC. A screenshot showing these gains is attached. We are leaving engaged the gain of 4 in the ESDOUTF filterbanks for ETMX-L3 as this gain gets us from the old 10-bit configuration to the 20-bit configuration. We are *not* engaging the '32bitDAC' FMs I prepared last week since the gain of 275.31 being applied by the DACs already takes care of getting us from the 20-bit configuration to the 32bit (28bit?) configuration. Jenne has accepted the FM changes in SDF.
Images attached to this comment
