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40m Log |
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Sun Apr 29 22:53:06 2018, gautam, Update, General, DARM actuation estimate
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Tue May 1 19:37:50 2018, gautam, Update, General, DARM actuation estimate 
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Mon May 7 16:23:06 2018, gautam, Update, General, DARM actuation estimate  
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Mon May 7 20:01:14 2018, Rorpheus, Update, General, Use anti-dewhitening + show CARMA/DARMA
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Thu May 10 14:13:22 2018, gautam, Update, General, More refinement of DARM control signal projection  
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Fri May 11 13:58:42 2018, rana, Update, General, More refinement of DARM control signal projection
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Fri May 11 19:02:52 2018, gautam, Update, General, More refinement of DARM control signal projection    
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Sat May 12 10:02:03 2018, rana, Update, General, More refinement of DARM control signal projection
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Sun May 20 17:43:01 2018, rana, Update, Electronics, How to choose resistors
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Mon May 14 18:58:32 2018, Kevin, Update, PonderSqueeze, Squeezing with no SRM  
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Tue Oct 2 23:57:16 2018, gautam, Update, PonderSqueeze, Squeezing scenarios
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Tue May 15 21:56:57 2018, gautam, Update, General, Stack measurement setup decommissioned
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Thu May 17 09:14:38 2018, Steve, Update, General, Stack measurement setup decommissioned 
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Message ID: 13835
Entry time: Fri May 11 19:02:52 2018
In reply to: 13833
Reply to this: 13836
13841
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Author: |
gautam |
Type: |
Update |
Category: |
General |
Subject: |
More refinement of DARM control signal projection |
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I was a bit hasty in posting the earlier plots. In the earlier plot, the "OLG" trace was OLG * anti dewhitening as Rana pointed out.
Here are the updated ones, and a cartoon (Attachment #5) of the loop topology I assumed. I've excluded things like violin filters, AA/AI etc. The overall gain scaling I mentioned in the previous elog amounts to changing the optical sensing response in this cartoon. I now also show the DARM suppression (Attachment #4) for this OLG and the DARM linewidths for RSE. I don't think the conclusions change.
Note that for Signal Recycling, which is what Kevin tells us we need to do, there is a DARM pole at ~150 Hz. I assume we will cancel this in the digital controller and so can achieve a similar OLG shape. This would modify the control signal spectrum a little around 150Hz. But for a UGF on the loop of ~150 Hz, we should still be able to roll-off the control signal at high frequencies and so the RMS shouldn't be dramatically affected.
Steve is looking into acquiring 4.5kohm Vishay Wirewound resistors with 1% tolerance. Plan is to install two in parallel (so that we get 2kohm effective resistance) and then snip off one once we are convinced we won't have any actuation range issues. Do these look okay? They're ~$1.50ea on mouser assuming we get 100. Do we need the non-inductive winding?
Quote: |
I think "OLG" trace is not labeled right; it would be good to see the actual OLG in addition to whatever that trace actually is.
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