Sheila, Haocun, Terry, Nutsinee

Still trying to lock 3MHz with PSL LO. We've bought back IQ demod into the loop (well, we tried). The most current plan we have is to loosely lock the 3MHz with signal out of PFD and hand off the locking to the signal that comes out of IQ demod by ramping gain up and down (I signal from PFD goes to INPUT 2 of the LO common mode board and I signal from IQ demod goes to INPUT1). We routed the input through an attenuator box that has -40dB of gain (before the common path slide bar). We double routed the signal from IQ demod so it had -80 dB of gain since it has to be able to engage before slowly ramping up and hopefully takes control of the loop (a model suggested that we can't have much more than a gain of -60dB for the UGF to fall on 1/f region. I'm not sure if PZT driver has a gain of 25 or 15 so could be off by a factor of ~1.6). What happened before for we left yesterday was once the PFD path (INPUT2) was engaged it did what it's supposed to do and brought the two peaks (+-3MHz +- offset) on top of each other but once the IQ demod path was engaged it kept pushing the two peaks away from each other.

matlab filter and gain used:

filter2 = zpk(-2.*pi.*[ 400 10],...

            -2*pi.*[ 0 1200 100e3 1 400], (1/400)*(1/10)*1200*100e3*400*...

            5.06*15*10.6e6*0.001);