We did a bit more analysis on the range drop reported in alog 30790. 

We computed the DARM (using GDS-CALIB_STRAIN) asd every 16 sec and recorded the height of each freqency bin (width = 1 Hz per bin) from 30-1000 Hz. At the same time, we also recorded the mean value of ASC control signals for that 16 sec segment. Then we correlated the darm high frequency peaks with the low frequency ASC control signals to see if we could id. the channels that modulated darm, which might further help the id. of scattering position. 

We used the data starting from Oct 24 11:00:00 UTC for ~2 hr (8096 sec), which should cover the entire period of the range drop. The darm peaks we focused on were the 48 Hz one and the 84 Hz one. 

For the 48 +- 0.5 Hz darm bin, the ASC channels showed most coherence were: OMC_B_PIT, MICH_Y, AS_C_PIT, SRC2_P.

For the 84 +- 0.5 Hz bin, the most interesting channels were: PRC2_Y, MICH_P, AS_C_PIT, SRC1_P