Hi, You probably want a long-time-constant steering of the FLL from the phase, to make sure any residue frequency offsets and low-frequency parts keeps the phase-control within range.
Cheers, Magnus On 2020-03-09 15:04, Bob kb8tq wrote: > Hi > > If you go that way, just run a pure FLL for the “main loop” and do the phase > on top of that. Assuming you are disciplining an OCXO, it works pretty well …. > Even more so if you keep time tagged phase ( to do frequency from phase) > and can look at some very long tau “frequency” as a section of the loop. > > Bob > >> On Mar 9, 2020, at 9:44 AM, Poul-Henning Kamp <[email protected]> wrote: >> >> -------- >> In message <[email protected]>, Matthias Welwarsky writes: >> >>>> Backing up a bit …. the objective is not to minimize overshoot or >>>> keep the loop from oscillating. The issue here is optimizing the noise >>>> output of the combination of GPS + OCXO when combined via >>>> the control loop. It’s a very different objective …. >>> Absolutely. The GPS will introduce a ton of noise and the objective for the >>> control loop is mainly to keep the influence of this noise away from the >>> GPSDO >>> output for small tau. You want the GPS only have an influence for large >>> tau, >>> ideally only countering the aging of the LO. >> Has anybody ever played seriously with separate frequency and phase >> adjustments ? >> >> I'm thinking 24h (to minimize GPS periodicities) frequency measurement >> and adjustment, with a continuous very weak proportional phase adjustment >> to come with measurement noise and rounding errors ? >> >> -- >> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >> [email protected] | TCP/IP since RFC 956 >> FreeBSD committer | BSD since 4.3-tahoe >> Never attribute to malice what can adequately be explained by incompetence. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
