Dan, Kiwamu, Evan
List of things done today:
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The ETMX UIM coil driver had tripped off sometime yesterday, and we drove down to the end station to turn it back on.
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In ETMY L3 drivealign, there is now compensation for the LVLN driver summing network. The compensation is a zero at 152 Hz and a pole at 3.2 kHz. This brings the high-frequency DARM phase response back to its previous shape. (See attachment.)
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In the DARM_OFFSET state, the DARM gain is now increased by a factor of 2 and the low-frequency boost (FM7) is engaged. This makes DARM more stable during the transition to dc readout. However, this throws off the procedure for determining the scale factor between OMC DC and AS45Q, so sometimes the transition causes the DARM gain to decrease.
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A high fifth-harmonic violin mode was causing the ETMY ESD to saturate, so there is now a stopband filter in the ETMY L3 LOCK filter bank (since DARM is full).
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LOWNOISE_ESD_ETMY has been rewritten for the new transition procedure. It has been tested (once) and works.
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We took a crossover measurement of ETMY L2. We tried to get ETMY L1 as well, but it seems currently that it's quite low (below 1 Hz). The gain in the L1 LOCK filter can be pushed up from 0.16 to 0.22 without issue (and maybe even further).