You are right. NTP, even over a poor internet connection can typically do better then the tens milliseconds we see with some NEMA GPS'.
But you eyes and human perfection is still even worse. You can't notice 40mS of error. In fact that would be a good experiment: Put two clocks up on a large computer monitor and make one always tick some random number of milliseconds away from system time and the other always thick on the system time. Then you click on the one you think is correct. Can you do better than a 50/50 guess. Keep incl=reasing the error until the guesses are about 90% correct. I bet you find you eyes are really bad. You ears are a little better and you might notice 40 mS by listening to the "tick" sound Another thought experiment is to show that the randomness of NMEA jitter does not matter would be to try and build a GPSDO that uses NMEA data. If you averaged over a long enough time it would work. Might be a way to set a Rb oscillator? One reason NTP works so well even over poor Internet connections is that it can use 5, 7 or even more other NTP servers to get the time and all it needs is that a few of them are good. I typically use five pool servers when I set up NTP On Mon, Aug 1, 2016 at 12:01 AM, Hal Murray <hmur...@megapathdsl.net> wrote: > > david-tay...@blueyonder.co.uk said: >> From your data and my own measurements, I feel that using the serial NMEA >> stream would, today, be a last resort, as an Internet sync would be >> considerably better. Would you agree with that? > > Depends on your internet connection and/or the specific GPS module you are > using. > > I don't know of any good GPS modules that use NMEA. I do know of really > crappy internet connections. Bufferbloat is the buzzword. > > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > 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. -- Chris Albertson Redondo Beach, California _______________________________________________ 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.