Hi Gee, now after a few cups of coffee … yes that does appear to be the sun.
———— The GPS system does it’s best to model the ionosphere and transmit that data. Unfortunately the model / model resolution is not as good as it could be. That lets the ionosphere creep into the solution more than it might with a perfect model. My *guess* (as in I have no data) is that constellations with a significant number of low(er) angle sats *and* a sun rise / sun set over one end of the constellation are the worst ones. That could easily be pure bunk. Bob > On Oct 20, 2014, at 7:31 AM, John C. Westmoreland, P.E. > <j...@westmorelandengineering.com> wrote: > > Bob, > > You mean the Sun, correct? > > Regards, > John > On Oct 20, 2014 4:16 AM, "Bob Camp" <kb...@n1k.org> wrote: > >> 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. >> > _______________________________________________ > 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.