[time-nuts] "GPS once a day issues" ?
michael.cook at sfr.fr
Mon Oct 20 05:03:48 EDT 2014
The constellation may repeat at 12hr intervals , but at any static position you will only see one per day , no? , the other being 180 degrees way. I only get one regular bump.
Le 20 oct. 2014 à 09:43, Magnus Danielson a écrit :
> Since the satellite orbit the earth with a period of 11 hours and 58 minutes, it is actually twice a day.
> On 10/20/2014 03:50 AM, Bob Camp wrote:
>> 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.
>>> On Oct 19, 2014, at 9:26 PM, Bob Stewart <bob at 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 at 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 at 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 at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
More information about the time-nuts