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Entry  Tue Sep 15 17:19:09 2020, gautam, Update, IOO, MC F spectrum  MCF_MCL.pdf
    Reply  Tue Sep 15 19:17:30 2020, rana, Update, IOO, MC F spectrum  
       Reply  Wed Sep 16 09:43:41 2020, gautam, Update, IOO, MC F spectrum  MCF_MCL.pdf
Message ID: 15576     Entry time: Wed Sep 16 09:43:41 2020     In reply to: 15574
Author: gautam 
Type: Update 
Category: IOO 
Subject: MC F spectrum  

This elog suggests that there is uniformly 1 stage engaged across all channels. I didn't look at the board to see what the jumper situation is, but only 1 stage of whitening is compensated digitally for both _F and _L. The Pomona box attached to the NPRO PZT input is also compensated digitally to convert counts to frequency.

I tried the gain re-allocation between VCO gain and FSS COMM (and also compensated for the cts to Hz conversion in MCF), but it doesn't seem to have the desired effect on the MCF SNR in the 5-50Hz band. Since the IMC stays locked, and I had already made the changes to mcup, I'll keep these gains for now. We can revert to the old settings if the IMC locking duty cycle is affected. Explicitly, the changes made were:

VCO gain: +7dB ---> +13 dB

FSS COMM: +6 ddB ---> +0 dB

The mcdown script wasn't modified, so the lock acquisition gains are the same as they've been. 


the "Pentek" whitening board that carries the MC channels has jumpers to enable either 1 or 2 stages of 15:150 whitening. Looks lik MC_F has 2 and MC_L has 1.

Attachment 1: MCF_MCL.pdf  91 kB  Uploaded Wed Sep 16 12:36:36 2020  | Hide | Hide all
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