The CW injection amptlitude, as measured at the HARDWARE_OUT, appears to have changed on restart May 12. So far, I have not been able to trace down the problem, and conlog is currently down so I cannot see a history of chagnes in the HARDWARE_OUT bank.
Figure 1 observations (10 minute trend of HARDWARE_OUT):
- Near the end of O1, the peak CW injection amplitude is ~1700
- On restart, May 12, the peak CW injection amplitude is ~780
- On May 26, when Keith Riles and I changed the CW injections to use the first attempt at a new actuation function, the amplitude of the injections drops to ~650 because the new actuation function is different than the old inverse actuation function (this might change if Keith restarts the CW injections with the revised filter, see LHO aLOG 27539)
Figure 2 observations (10 minute trend of CW_OUT):
- On restart, May 12, the peak CW injections is the same as at the end of O1, ~7.5e-23
- After changing to the actuation function method, the amplitude changes to ~650 (off scale on figure 2)
Need conlog to investigate further.
On Jan 20, there was a site-wide power outage (alog 25041), and after everything was restored, one of the filter modules (FM3) was not turned on, but it should have been. This was the 1/AI2 filter with design:
zpk([1.2627e3 - i*2.6133e3;1.2627e3 + i*2.6133e3],[7000;7000],1,"n")
Turning this off flips the phase of the injected signal, but it doesn't really explain the drop in the signal amplitude that I would have expected.
One thing interesting is that there was considerable high frequency noise on the PINJX_HARDWARE_OUT time series that is reduced by turning off the 1/AI2. I plotted the spectrum of the HARDWARE_OUT channel before and after, separated by 24 hours so that the pulsar injections are approximately the same amplitude. Sure enough, with the 1/AI2 filter on, there is a large peak at 7 kHz with an amplitude nearly as large as the highest frequency pulsars. Is this why the pre-power outage time series is about twice as large? It is certainly suspicious...
See attached figures for pre- and post-power-outage spectrum.
