Is there a list of GPS timing receivers that provide the sawtooth correction message or implement sawtooth correction internally?
I assume there is a design compromise that prevents economically phase locking the GPS receiver clock to the GPS signal to remove that contribution to timing error. On Tue, 2 Oct 2012 09:18:35 -0700, "Tom Van Baak" <[email protected]> wrote: >Correct, all GPS timing receiver boards have jitter, sawtooth, or random >wandering of some sort, on the order of tens of nanoseconds. This is normal. >And so if you use a counter to compare the OCXO 1 Hz with the GPS 1PPS, a TIC >resolution of 1 ns or 500ps is sufficient. I would say 25 ps is overkill. > >In many cases (e.g., Motorola Oncore series) the sawtooth correction message >itself has a granularity of 1 ns. So again, a 25 ps measurement is especially >overkill given a correction granularity of 1 ns. Depending on the receiver >applying the correction will improve the average timing performance by, say, a >factor of 3. > >See: http://www.leapsecond.com/pages/m12-adev/ > >As for your averaging question, yes, the OCXO will move during the average. >This is normal. That's why too long an averaging interval is problematic. >Depends on the quality of the OCXO. And if the averaging interval is too >short, you pick up too much GPS jitter. Depends on the quality of the GPS >receiver. There is no perfect answer; instead you choose something between too >short and too long. _______________________________________________ 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.
