Daniel, a timing GPS receiver is not a GPSDO so its PPS is wandering about the nominal position. Using a digital oscilloscope, I can see how much the total wander is by activating the infinte persistence mode of the display. After 10 minutes, 1 hour, 1 day or whatever you have an idea of the total "coverage" of the wander. The trigger comes from a Z3815A reference. To see the "dance" of the PPS coming from a GPS receiver, a simple crystal oscillator as a reference is enough: use your microprocessor to generate a PPS from its clock and visually compare this generated PPS with the GPS PPS by a 'scope.
On Tue, Apr 23, 2013 at 7:49 AM, Daniel Ginsburg <dginsb...@gmail.com>wrote: > > On 23.04.2013, at 6:15, Hal Murray wrote: > > > > >> I wonder, what kind of timing GPS gives 112ns wander? > > > > How good is your antenna? 112 ns is roughly 112 feet. That's not at all > > surprising if your antenna is inside or under trees. > > > > > Not perfect, but should be reasonably good. It's an external magnetic > antenna on my windowsill. > Anyway, +-400ns I'm seeing translates to +-120m in position. My surveyed > location is better than this. > > > You might watch the number of satellites and/or watch the position while > it > > does a survey. > > > > 6-10 SVs, with PDOP in range 1.6 - 3.9 (about 2.0 most of the time). > > > > > -- > > 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. > > _______________________________________________ > 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.