Hi John, Brian, actually we set D to 0, and use P and I gains. Yes, the DACGAIN is an overall gain of the loop output - to normalize for different oscillator voltage/frequency sensitivities. I forgot that the DACGAIN is limited to 10,000, so instead of setting it to 20,000 one can set it to 10,000 and multiply the P and I parts both by 2x, that gives pretty much the same effect as setting DACGAIN to 20,000. Please note that aging and tempco compensation may then take a couple of days to fully settle again. I have not tried such high gains since we don't have any oscillators here with such small F/V range, please advise what you find out. bye, Said In a message dated 7/27/2010 19:04:36 Pacific Daylight Time, [email protected] writes:
> That part I understand (your drawing), its a basic phase lock loop. > What I am having trouble with is the Fury's commands relationship. OK. Sorry for the BW. Basically you tune a loop by starting with the P, I, and D set to zero. You slowly crank up the P until it starts to become unstable. (Put in a small step perturbation and look at the response for ringing) Then crank up the D until it stabilizes, then crank up the P again. When you have got a stable fairly well performing loop, you introduce some I. You may have to tweek P and D to keep stability. It looks like your system has an overall gain (DACG) and a P and D controller gain. This is not uncommon to avoid switching a bunch of caps. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
