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Mon Oct 9 01:29:26 2017, gautam, Update, LSC, DRMI Nosie Budget v3.0 7x
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Mon Oct 9 11:55:01 2017, Koji, Update, LSC, DRMI Nosie Budget v3.0
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Mon Oct 9 22:18:34 2017, gautam, Update, LSC, AS55Q Dark Noise
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Tue Oct 10 22:04:06 2017, rana, Update, LSC, AS55Q Dark Noise
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Wed Oct 11 14:42:03 2017, gautam, Update, LSC, AS55Q Dark Noise
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Wed Oct 11 19:31:32 2017, gautam, Update, LSC, AS55Q Dark Noise
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Thu Oct 12 01:50:11 2017, gautam, Update, LSC, AS55Q Dark Noise
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Thu Oct 12 12:17:28 2017, gautam, Update, LSC, AS55Q Dark Noise
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Fri Oct 13 12:26:12 2017, gautam, Update, LSC, AS55Q Dark Noise
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Mon Oct 16 16:01:04 2017, gautam, Update, LSC, AS55Q Dark Noise 
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Tue Oct 17 19:31:53 2017, gautam, Update, LSC, AS55Q Dark Noise 
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Tue Nov 7 17:45:05 2017, gautam, Update, LSC, DRMI Nosie Budget v3.1   
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Tue Nov 7 22:56:21 2017, gautam, Update, LSC, DRMI locking recovered
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Wed Nov 8 00:28:16 2017, gautam, Update, LSC, Laser intensity coupling measurement attempt
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Wed Nov 8 09:37:45 2017, rana, Update, LSC, DRMI Nosie Budget v3.1
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Wed Nov 8 09:59:12 2017, gautam, Update, LSC, DRMI Nosie Budget v3.1
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Wed Nov 15 01:37:07 2017, gautam, Update, LSC, DRMI low freq. nosie improved 
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Thu Nov 16 00:53:26 2017, gautam, Update, LSC, DRMI noise sub-budgets 
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Message ID: 13380
Entry time: Fri Oct 13 12:26:12 2017
In reply to: 13378
Reply to this: 13382
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Author: |
gautam |
Type: |
Update |
Category: |
LSC |
Subject: |
AS55Q Dark Noise |
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Attachment #1 - Measured / modelled noises for AS55 demod board. I've plotted quadrature sum of the LISO trace with the SR785 noise floor with input terminated to ground via 50ohm. Note that these measurements were made after all the changes in the marked up schematic in the previous elog were implemented.
Both channels should be identical - I don't understand why the I channels are noisier than their Q counterparts. This is almost certainly a problem on the daughter board, as the orange traces are pretty much identical for both channels.
The dark red curves were measured by shorting the inputs to D040179 to ground via 50ohms using some Pomona minigrabbers - I wanted to avoid ripping the daughter board out, but this probably explains the excess noise compared to the green trace at low frequencies. All other measurements were made with the board installed in the LSC rack eurocrate, with the LO input driven at the nominal level (I didn't measure this yesterday but a measurement from ~6months ago says that this level is 1.5dBm). |
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