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Thu Sep 4 19:39:36 2014, Tara, Evan, DailyProgress, FSS, TTFSS OLTFs
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Sun Sep 7 11:54:21 2014, Evan, DailyProgress, FSS, TTFSS OLTFs, residual frequency noise    
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Mon Sep 8 04:20:41 2014, rana, DailyProgress, FSS, TTFSS OLTFs, residual frequency noise
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Wed Oct 2 19:09:31 2019, anchal, DailyProgress, FSS, TTFSS OLTFs; Repeated this 5 year old measurement
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Thu Jan 9 19:00:19 2020, anchal, DailyProgress, FSS, TTFSS OLTFs
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Wed Jan 22 14:16:28 2020, anchal, DailyProgress, FSS, TTFSS OLTFs
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Wed Jan 22 16:00:26 2020, anchal, DailyProgress, FSS, TTFSS OLTFs with Maximum Gain
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Thu Jan 23 19:23:03 2020, anchal, DailyProgress, FSS, NFSS Boost Stage
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Message ID: 2443
Entry time: Wed Oct 2 19:09:31 2019
In reply to: 1504
Reply to this: 2508
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Author: |
anchal |
Type: |
DailyProgress |
Category: |
FSS |
Subject: |
TTFSS OLTFs; Repeated this 5 year old measurement |
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I repeated the measurement done by Tara and Evan to update residual NPRO noise in our noise budget.
Quote: |
Acutally it does look like it's a 50 Ω loading issue. I find that when 50 Ω inline terminators are added to OUT1 and OUT2, the measured OLTF is reduced by a factor of 1.6. This explains the discrepancy between the SR785 and HP4395 measurements. I've attached the corrected OLTF plots, along with plots of a vector fit, and the expected residual frequency noise [assuming a free-running NPRO noise of 104 Hz/Hz1/2 × (1 Hz / f)].
South UGF is at 200 kHz with almost no phase margin. We need to fix this.
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Conclusions:
- Clearly, the North side's boost isn't working as was reported in CTN:2384
- South side looks as healthy as North in CTN:1504
- Tomorrow I'll update the noisebudget with new residual NPRO noise, for now, the second plot gives the prediction.
- It matches very well with our observed floor of noise in 100Hz to 1 kHz region in the beatnote spectrum.
Code and Data |
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