[time-nuts] GPS 1 PPS Averaging ?
Tom Van Baak
tvb at leapsecond.com
Sun Mar 13 23:16:21 EST 2005
> Based on Tom's post suggesting looking at one day prompted me to look at
> what averaging is needed for one day readings, hence the subject post.
Yeah, the reason I suggested one-day averaging is
that there are a host of effects you notice when you
use short GPS averaging times: sawtooth, jitter,
wander, counter resolution, GPS orbits, multi-path,
diurnal temperature, etc.
Now these effects are all very interesting, to be sure,
but in the context of measuring the performance of
a cesium, or watching the effect of a C-field change,
it is my opinion that all these effects get in the way
of what you are trying to measure. Hence the
suggestion to boil it down to one point per day.
An obvious by-product of one-point-per-day is that
it forces one to be very patient, which, I think, is
a necessary lesson when doing performance
comparisons with cesium clocks. It is easy to get
excited about a "trend" between lunch and dinner,
only to find your cesium decides to change its mind
between dinner and breakfast. Best to leave the
poor thing alone for a week before you jump to any
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