40m
QIL
Cryo_Lab
CTN
SUS_Lab
TCS_Lab
OMC_Lab
CRIME_Lab
FEA
ENG_Labs
OptContFac
Mariner
WBEEShop
|
PSL |
Not logged in |
 |
|
Wed Jan 29 14:49:48 2020, anchal, DailyProgress, BEAT, Beanote Spectrum vs FSS Gain Values
|
Wed Jan 29 15:58:26 2020, anchal, DailyProgress, BEAT, Beanote Spectrum vs FSS Gain Values
|
Fri Feb 7 09:57:32 2020, anchal, DailyProgress, BEAT, Spanned gain parameter space in NFSS and checked beatnote
|
Fri Feb 7 18:12:03 2020, anchal, DailyProgress, BEAT, Spanned gain parameter space in SFSS and checked beatnote
|
Mon Feb 10 11:07:33 2020, anchal, DailyProgress, BEAT, Spanned gain parameter space in PMCs and checked beatnote
|
Thu Feb 13 15:27:18 2020, anchal, DailyProgress, BEAT, Further iterated back and forth to optimized FSS Gains.
|
|
Message ID: 2526
Entry time: Mon Feb 10 11:07:33 2020
In reply to: 2525
Reply to this: 2531
|
Author: |
anchal |
Type: |
DailyProgress |
Category: |
BEAT |
Subject: |
Spanned gain parameter space in PMCs and checked beatnote |
|
|
I took beatnote measurements and spanned gain values in the PMC to see if stability issues in PMC loops can be affecting the FSS downstream.
Method
- I used BNspec.py with default settings (10 kHz bandwidth at 15.625 kSa/s for 60s) while spanning the parameter space of PMC gains.
- The beatnote frequency was robustly within 2 kHz of 27.34 MHz during this whole measurement.
- Overall experiment was run by spanParamSpace.py script.
Inference
- I calculated the integrated total beatnote frequency noise in the frequency range 200 Hz to 1 kHz where the total noise is expected to be dominated by coating Brownian noise.
- Unstable regions in the parameter space are clearly visible.
- Ideally, the noise in beatnote frequency should have very minimal coupling with the gain values in PMC loops.
- This has been found true indeed for the south side but not so much on the North side.
- Very clearly there is a corridor from -3 dB to 8 dB in NPMC gain where noise remains low. We generally use 7 dB value.
- But this might just be too bad PMC loop causing light amplitude noise in the output.
- There is a bulge at 400 Hz in the beatnote freqeuncy noise. I can also see a broadened oscillation in PMC error signals around that frequency on both sides.
- I'm afraid that maybe the North PMC is causing big mode mismatch at 400 Hz causing the noise in the beatnote frequency. Or is that not possible?
Data |
|
|