I think what you are observing, is the detail of how the control loop transitions from frequency locked to phase locked. And this has more to do with the divider chain reset and phase detector than anything else.
Note that several of the hobbyist/E-bay GPSDO's (especially the "Chinese GPSDO") do not have a phase locked mode, at best they are frequency locked, and many of these have a consistent bias based on the gating of the frequency counter (typically their counter gating adds an extra count, meaning that when they are frequency locked to GPS they are running slightly slow). Tim N3QE On Wed, Feb 10, 2016 at 2:17 PM, Bob Stewart <b...@evoria.net> wrote: > I've been running up a number of OCXOs lately, all Trimble 34310-T. For > most of them, the DAC moves in the negative direction after lock. But > there are a few where the DAC moves more positive. Is this an indication > of a different cut of crystal, or is retrace direction more or less random? > > Bob - AE6RV > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.