keith.riles@LIGO.ORG - posted 17:07, Thursday 07 February 2019 - last comment - 11:10, Friday 08 February 2019(46858)
CW injections restarted wth new actuation function
I have restarted the CW injections using the new actuation function that Evan posted here. The attached screen shot confirms the expected reduction in the envelope of H1:CAL-INJ_CW_OUT. The new injections are running as of GPS 1233622649 (Feb 08 2019 00:57:11 UTC).
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To understand what differences we should expect between previous and future CW injection recoveries, I have looked at differences between the actuation function used since ER13 and the one now in use. The attached graphs show the intended 1.47 magnitude rescale (near DC) and an additional time delay ranging from 115 usec at 10 Hz (low end of CW injections) and 138 usec at 4000 Hz.
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Responding to an email query from Evan: The old actuation function used from ER13 until yesterday was the same one used in O2. Given the known 1-clock-cycle discrepancy in that run (discovered near the end of the run) and the additional 1-cycle delay from the new Guardian-driven actuation, we do expect to see a ~120 usec difference between these functions at low frequencies. Preliminary estimates from Jessica's injection monitoring suggest a ~130 usec discrepancy in recovery. So I think we're in good shape. We should know better in a week or so after accumulating more statistics.