Building on work last week, we installed a 2nd PI AI chassis (S1500301) in order to keep the PI signals separate from the ESD driver signals. Original PI AI chassis S1500299.
We routed the LD32 Bank 0 thorugh the first PI AI chassis to the ESD drive L3, while keeping the old ESD driver signal driving the PI through the new PI AI chassis.
We routed the LD32 Bank 1 to the L2 & L1 suspension drive.
We did not route LD32 Bank 2 or Bank 3 to any suspensions. The M0 and R0 signals are still being driven by the 18 bit DACs.
The testing did not go as smoothly as planned, a watchdog on DAC slot 5 (the L1&L2 drive 20 bit DAC) continousouly tripped the ESD reset line. We solved this by attaching that open DAC port (slot 5) to the PI AI chassis to clear the WD error.
Looks like we made it to observing.
F. Clara, R. McCarthy, F. Mera, M. Pirello, D. Sigg
Part of the implication of this alog is that the new LIGO DAC is currently installed and in use for the DARM actuator suspension (the L3 stage of ETMX). Louis and the calibration team have taken the changes into account (see, eg, alog 80155).
The vision as I understand it is to use this new DAC for at least a few weeks, with the goal of collecting some information on how it affects our data quality. Are there new lines? Fewer lines? A change in glitch rate? I don't know that anyone has reached out to DetChar to flag that this change was coming, but now that it's in place, it would be helpful (after we've had some data collected) for some DetChar studies to take place, to help improve the design of this new DAC (that I believe is a candidate for installation everywhere for O5).
Analysis of glitch rate:
We selected Omicron transients during observing time across all frequencies and divided the analysis into two cases: (1) rates calculated using glitches with SNR>6.5, and (2) rates calculated using glitches with SNR>5. The daily glitch rate for transients with SNR greater than 6.5 is shown in Figure 1, with no significant difference observed before and after September 17th. In contrast, Figure 2, which includes all Omicron transients with SNR>5, shows a higher daily glitch rate after September 17th.
The rate was calculated by dividing the number of glitches per day by the daily observing time in hours.