Hi The GPS constellation repeats roughly once a day. It is not at all uncommon to have a “worst case” sattelite geometry for a given antenna location. If you have one, it will repeat once a day and show up as a bump in the timing out of your GPS module. If you track long term data, it will / may / can keep you from getting to the sort of stability you would expect in the 100,000 second range. It’s one of the main reasons that things like GPSD-Rb’s lock up with time constants much longer than 100K seconds. Yes having a Cs or something similar helps a lot looking for this sort of thing.
Bob > On Oct 19, 2014, at 9:26 PM, Bob Stewart <[email protected]> wrote: > > Hi Bob Camp, > > > In your response to Chris, you said: "Once you have it “right” you really > need to check it over a month or two to watch for GPS “once a day” issues. " > > Could I ask you what you meant by these "once a day issues"? Was this a > general comment, or was it about something specific? As you know I'm working > on a GPSDO and am doing a lot of testing, so if there's something else I > should be looking for, please let me know. > > > Bob - AE6RV > > > ________________________________ > _______________________________________________ > 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.
