[time-nuts] "GPS once a day issues" ?

Hal Murray hmurray at megapathdsl.net
Mon Oct 20 17:15:28 UTC 2014


kb8tq at n1k.org said:
> 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.  

There is another layer.  In addition to the "normal" once-a-day type 
differences, the pattern of satellites drifts slowly from day to day.  So 
there is another pattern with a period of something like a month.  If you 
have a marginal setup, for example an indoor antenna, you can see things like 
the holdover times drifting both in time-of-day when they happen and in 
length of holdover as the satellite pattern at dawn/dusk changes.

Of course, at that level of detail, there are lots of other contributions 
like rain that will also show up and may be more important.


-- 
These are my opinions.  I hate spam.






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