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 <[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
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