[time-nuts] I thought GPS repeated every 12 hours (-2 minutes)

Bob Camp kb8tq at n1k.org
Mon May 23 23:37:00 UTC 2016


Hi

Well, *maybe* there is a 24 hour component in the GPS constellation :)

Indeed a lot of stuff repeats at the 24 hour point. The ionosphere is a bit different at midnight than at noon.

Bob

> On May 23, 2016, at 6:43 PM, Skip Withrow <skip.withrow at gmail.com> wrote:
> 
> Hello Nuts,
> 
> I am attaching a capture from Lady Heather of a 3-day run.  You can see the
> temperature vary by 7C over each day.  The TB is being run open loop and
> another GPSDO 10MHz input to the unit instead of the unit's oscillator.
> 
> I expected the purple line to repeat every 12 hours based on the GPS
> constellation being the same (which maybe it kind of does), but there is
> definitely a 24 hour repeat.  What is really weird is that the number of
> satellites that LH sees also repeats on a 24 hour cycle, not 12 (bottom
> trace).
> 
> Any help in understanding this behavior?  Thanks in advance.
> 
> Skip Withrow
> 
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