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| 40m Log |
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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: 13376
Entry time: Thu Oct 12 01:50:11 2017
In reply to: 13374
Reply to this: 13378
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| Author: |
gautam |
| Type: |
Update |
| Category: |
LSC |
| Subject: |
AS55Q Dark Noise |
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I worked on the daughter board a little more in the evening. I have somehow managed to make the dark noise ~25% worse [Attachment #1].
- Earlier in the day, I had switched out both on-board AD797s for OP27. The latter has ~3x the input voltage noise, and LISO modeling suggests that this is the dominant contribution to the output voltage noise.
- There are some differences in the actual components with which the board is stuffed, and the schematic.
- After updating the LISO model, I expect to get an output voltage noise of ~50nV/rtHz. But I measured ~2x this value (measured with LO input of demod board driven, RFPD input terminated).
- While I had the board out, I replaced most of the installed thick-film resistors with thin film ones. For good measure, I also changed the AD829s.
After making all these changes, I re-installed the card in the eurocrate and repeated the measurement. The Q channel noise was close to the expected value (~50nV/rtHz), but the I channel is twice as noisy. I will continue this investigation tomorrow. |
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