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AdV-COM (AdV commissioning (1st part) )

koley - 23:54 Tuesday 18 July 2017 (38677)

Lines in DARM at 411 Hz and 438 Hz jump in frequency

The noise band around 411 Hz which was quiet stable in frequency throughout jumped in frequency by -2Hz to 409 Hz around 10:00 UTC on 17th July. A similar jump by +4 Hz was observed for another line at 438 Hz to 442 Hz at the same time. It is a good starting point to investigate what changed after that lock and the reason behind these lines.
Attached you will find the spectrograms during the time.

Images attached to this report

Comments to this report:

fiori - 9:45 Wednesday 19 July 2017 (38681)

These frequencies "match" with frequencies which were noted NOT to rise when exciting SDB1 (see 38610): 266Hz, 410Hz, 438Hz. Do we also observe a jump of the 266Hz?

Just to complete: some effect was maybe observed at the 410hz line during tests of vertical displacements of SDB1 (see 38444).To be added that projection of scattered light noise from SDB1 tower flange points to a limitation around 400Hz (38103).