AdV-COM (AdV commissioning (1st part) )swinkels - 12:22 Thursday 07 June 2018 (41732)
Print this reportMissing drum modeLooking at the spectrum around 7810 Hz, only 3 drum modes can be seen at 7804.7, 7806.4 and 7809.0 Hz. The last one is a doublet separated by 10 mHz, so it is likely that two modes are almost overlapped by chance. Note that the frequencies shifted a bit with respect to one year ago, when they were located at 7808, 7810, 7811 and 7812 Hz. The shift is likely related to the upgrade from metal wires to glass fibers. This means that the identification has to be done from scratch, and that the data of the online monitor up to now is useless. I will update the configuration to account for the shift. To speed up the identification, it would be good to play a bit with the ring-heaters in the next weeks.
