Reports until 11:16, Tuesday 25 October 2016
H1 PSL
daniel.sigg@LIGO.ORG - posted 11:16, Tuesday 25 October 2016 - last comment - 14:00, Tuesday 25 October 2016(30846)
PMC HVMon whitening filter

Jason Daniel (WP 6273)

We added a whitening filter to the PMC HV monitor in the PMC fieldbox, D1001619. The changes are:

This generates a whitening filter with a zero at 1 Hz, a pole at 100 Hz and a DC gain of –1. The inverse of this filter has been added to the corresponding PSL PMC filter bank, so that the slow readbacks are unchanged.

The attached spectrum shows the PZT high voltage which is 50 times the monitor readback and has an additional pole at 770 Hz which is formed by the output series resistor, see alog 30729. The noise level of the unwhitened HV monitor was at 0.2 mV/√Hz before the change, see alog 30648. The signal  is at least a factor of 10 above ADC noise at all frequencies and is coherent with the temporary channel hooked up to EXTRA_AI_1. The later is no longer needed.

Non-image files attached to this report
pmc_hvmon_161025_A.pdf
Comments related to this report
daniel.sigg@LIGO.ORG - 14:00, Tuesday 25 October 2016 (30855)
Link

The two SR560 units which were used for temporarily monitoring the HVMons have been disconnected and brought back to the shop.