Dave O, Ellie, Sheila

Tonight we had some difficulty with ALS DIFF lossing lock.  We have plotted a few of these, and each of the times that we have looked at (about 4) the ALS_C_DIFF_A_DEMOD_RFMON drops significantly (12dB) about 0.3 seconds before anything else changes.  We checked that the BS is not moving (no oplev glitches) at these times.  This was a bit confusing. 

Ellie also found one of the glitches similar to what we saw in alog 15242.  However, the drop in RFMON came before this glitch.  Previously we saw that these glitches were present even without DIFF locked. 

Here is a collection of lock loss times (there were many more)

3:15:39 UTC DEC 3 

3:19:30

3:42:50

3:52:48

5:53:46

7:26:33