On 23.04.2013, at 12:50, Azelio Boriani wrote: > 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. >
Ah, I see now. Preoccupied with issue at hand I wasn't attentive enough and I somehow thought that you were talking about 112ns wide sawtooth, while in fact you were talking about wander in sense of ... well ... wander. Sorry for the confusion. > > On Tue, Apr 23, 2013 at 7:49 AM, Daniel Ginsburg <[email protected]>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 -- [email protected] >>> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> _______________________________________________ >> 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. >> > _______________________________________________ > 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. _______________________________________________ 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.
