Reports until 15:28, Monday 27 March 2017
H1 DetChar (DetChar)
miriam.cabero@LIGO.ORG - posted 15:28, Monday 27 March 2017 - last comment - 12:26, Tuesday 28 March 2017(35116)
Blip-like injections

Evan, Miriam,

While L1 was having a small lock loss, we made a series of injections (with H1 in comissioning mode) in the H1:SUS-ETMY_L2_DRIVEALIGN_Y2L_EXC channel. The injections are single sine-gaussian pulses that simulate blip glitches (see https://ldas-jobs.ligo-wa.caltech.edu/~miriam.cabero/sine-gaussian.png ).

We started very quiet and slowly increased the amplitude, so that only the last 3 of the 9 injections appear in GDS-CALIB_STRAIN. The GPS times of the injections are:

1174684631

1174684680

1174684715

1174684745

1174684793

1174684854

1174684889 *

1174684945 *

1174685355 *

* Can be seen in CALIB_STRAIN

 

We will be repeating this kind of injections at opportunistic times (L1 not observing) in the next days, taking different blip morphologies, and different amplitudes.

Comments related to this report
andrew.lundgren@LIGO.ORG - 12:26, Tuesday 28 March 2017 (35143)DetChar, ISC, SUS
Link 

Only the loudest of these saturated the noisemons, and it did so by hitting an analog limit at plus/minus 22000 counts.

I projected the drive signal into noisemon counts and looked at the last three injections on the list. In the first two, the noisemon signal tracks the drive, and the subtraction of the two is just noise. In the last (loudest) injection, the noisemon hits an analog saturation at both plus and minus 22,000 counts leaving a huge glitch in the subtracted data.

This is good because it suggests that the only important analog limit in the noisemon is this threshold. I don't have time to document it now, but I've tried the same with a set of loud detchar injections, which go up to hundreds of Hz, and I get the same behavior. So when the drive signal does not push the noisemon beyond 22,000 counts, we can trust the subtraction, and anything we see has entered the signal between the DAC and noisemon; it's a glitch in the electronics and not a result of the DARM loop.

Attached are the three subtractions, noisemon minus projected drive signal.
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