Hi With “real” (who knows how real) Rb based GPSDO’s selling below $250, it’s not clear that running an Rb in a lash up that makes it look like a TBolt is a worthwhile exercise. Unless you can get the time constants out into the “several days” range, a manual adjust is a much better way to go. Since we are talking about a “I just want to plug it all in” sort of approach here, anything more than “set and forget” appears to be out of the question.
Bob > On Mar 12, 2016, at 10:48 PM, Charles Steinmetz <csteinm...@yandex.com> wrote: > > I wrote: > >> With the right settings, a PRS10 *does* work extremely well with the PPS >> input from a GPS. They do generally take several days or more to lock, >> because of the long time constants involved. > > Bob replied: > >> I would call having to wait a few days for it to lock a bit of a >> disadvantage. Even more so for those with an antenna challenged environment >> that gives them dropouts every few hours. > > Well, one is certainly free to use shorter time constants to achieve lock > faster. The very long TCs simply allow one to exploit the exemplary > stability of the PRS10 for performance much better than what an OCXO-based > GPSDO can deliver. If you are content with the stability of, say, a TBolt, > you can replicate that performance by adjusting the PRS10 loop to match TBolt > dynamics -- in which case it will lock in a comparable time. > > WRT holdover, the long TC and the inherent stability of the PRS10 mean that > it will stay very close to the GPS PPS even over long holdover periods, so > re-acquiring lock does not take nearly as long as acquiring it initially. > For the same reason, a PRS10 set up for maximum stability can acquire lock > even if there are holdover periods during the acquisition process (in both > cases, assuming that the GPS does not output "bad" PPS pulses when it is not > locked to GPS). > > In principle, one might be able to begin the process by setting the PRS10 > loop "tighter," then changing the loop constants in one or more steps after > it achieves initial lock. I have not tried this, and do not know if changing > the loop programming on the fly upsets the PRS10 phase. If not, it should > work (and one could even program a BBB, 'uino, or other small processor to do > it automatically). > > Best regards, > > Charles > > > _______________________________________________ > 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.
