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Message ID: 1536
Entry time: Fri May 1 01:32:43 2009
Reply to this: 1537
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| Author: |
Yoichi |
| Type: |
Update |
| Category: |
Locking |
| Subject: |
166MHz LO phase adjustment |
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I continued to adjust the REFL_2I demodulation phase.
I first optimized the demod phase for SRCL in the DRMI configuration (the error signals were DDs).
Then I restored the full IFO and offset locked it.
Before handing the DARM to RF, I adjusted the 166MHz delay line to maximize the SRCL signal at REFL_2I.
I did this before the DARM RF hand off because changing the delay line setting also changes the AS166 demodulation phase.
After this, I adjusted the digital phase shifter for AS166 to maximize the DARM signal for this port.
I also adjusted the digital demodulation phase of PD11 (REFL_2I) because the optimal demodulation phase for the initial lock acquisition is somewhat (15deg)
different from the optimal demodulation phase for the SRCL when the central part is locked with the DD signals.
This happens because the resonant condition of the central part (lock points of the recycling cavities) changes when the error signals are switched to the DD signals,
due to the offset in the DD signals. This is not good and should be fixed by the optimization of the DD demodulation phases.
Finally, I reduced the CARM offset to zero and tweaked the delay line a bit to maximize the arm power.
Right now, the locking script runs fine until the end.
At the end of the script, I was able to engage the boost on the CM board. |