Reports until 19:21, Friday 06 February 2015
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sheila.dwyer@LIGO.ORG - posted 19:21, Friday 06 February 2015 (16541)
increased bandwidth for ALS offload to suspensions

Since the wind has been bad all afternoon, we took the chance to look at the filters in the suspension offloading path known as tidal.  I copied the plant inversion we are using for the UIM in DARM, with this we were able to puch the bandwidth up to about 0.03 Hz.  We also raised the limit on this to about 10 um.  With this change we went from being able to lock the arms with green for less than about a minute to being able to lock for about 5-10 minutes.  Eventually the "tidal" feedback reaches the limit, and within a minute of that happening the VCO rails.  We could increase the limit further to possibly hold things a few more minutes, but the wind is getting worse. 

Attached is a screen shot showing the new arrangement of filters and gains for this. 

Images attached to this report