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Tue Jul 15 12:44:08 2008
DRFPMI with DC readout
Last night, despite suspect alignment, we were again able to reduce the CARM offset to zero using
the RF signal.We were also able to transfer to dc readout taking calibrated spectra in both states.
DC readout shows a marked improvement over RF above ~1kHz but introduces some noise around 100Hz.
Broadband sensitivity appears to be more than ten times worse than previously. The calibration
being used remains to be confirmed.
Engaging the ETMY dewhitening caused lock to be lost. We'll check this today. The OMC alignment loops
may also need some attention.
We looked at REFL_166 as a candidate for CARM, at present POX still looks better.
The DARM filters were modified to reduce excess noise around 3Hz. Updating filter coefficients does
not cause loss of lock.