evan.hall@LIGO.ORG - posted 03:05, Sunday 26 July 2015 - last comment - 00:48, Wednesday 12 August 2015(19935)
Some things not in the guardian
- SR3 20 Hz elliptic LPF (for M2 oplev coupling) was replaced with a more gentle 8 Hz LPF with slightly less attenuation in the stopband, but more attenuation around 20 Hz. [Attachment.] This was done without knowledge of the SR3 oplev OLTF, so it is possible we can design a more aggressive filter.
- dHard pitch gain is turned up by a factor of 2 (to 20 ct/ct), since it seems like it is able to kill that abominable 1 Hz pitch oscillation.
- cHard pitch gain turned down by 20 dB (by turning on FM1), and a 9 Hz LPF is engaged to kill angular control noise that can be seen in DARM between 10 and 20 Hz.
Images attached to this report
Comments related to this report
I think that evan meant to say he increased the gain for CHARD by 20 dB by engaging FM1