Hi Yes, but there’s this large object in the sky that modifies the ionosphere as it travels in a “about one a day” track. It appears to be coming up just about now, but I do need more coffee to be sure …
The combination of the constellation and the ionosphere are what I believe give you the once a day (rather than once per 12 hours) bump. Bob > On Oct 20, 2014, at 3:43 AM, Magnus Danielson <mag...@rubidium.dyndns.org> > wrote: > > Bob, > > Since the satellite orbit the earth with a period of 11 hours and 58 minutes, > it is actually twice a day. > > Cheers, > Magnus > > On 10/20/2014 03:50 AM, Bob Camp wrote: >> 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 <b...@evoria.net> 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 -- 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. _______________________________________________ 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.
