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Sat Feb 16 18:32:01 2013, yuta, Summary, RF System, phase tracker: OLTF  
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Thu Feb 28 05:54:54 2013, yuta, Update, RF System, phase tracker: calibration 
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Thu Feb 28 06:51:17 2013, yuta, Update, RF System, phase tracker: noise level
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Sat Mar 2 20:09:12 2013, yuta, Update, RF System, phase tracker: DAQ noise limited
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Message ID: 8200
Entry time: Thu Feb 28 06:51:17 2013
In reply to: 8199
Reply to this: 8214
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Author: |
yuta |
Type: |
Update |
Category: |
RF System |
Subject: |
phase tracker: noise level |
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I measured noise level of the phase tracker by inputting constant frequency RF signal from marconi.
Measured frequency noise was ~2 Hz/rtHz @ 100 Hz. It's not so good.
What I did:
1. Unplugged 11MHz marconi and put RF signal to the beatbox from this. Frequency and amplitude I put are 100 MHz and -3 dBm.
2. Measured spectra of phase tracker outputs, C1:ALS-BEATX_FINE_PHASE_OUT, C1:ALS-BEATY_FINE_PHASE_OUT.
3. Calibrated using the factor I measured (elog #8199).
4. Put marconi back to orignal settings.
Result:

Discussion:
- According to Schilt et al., this noise level is not so good.
- By changing the delay-line cable length or optimizing whitening filter etc., we can improve this.
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