[time-nuts] Is possible precise 1pps?
David J Taylor
david-taylor at blueyonder.co.uk
Thu Mar 14 02:57:15 EDT 2013
This brings up something that I have wondered about for a while.
The Garmin GPS18x (and many other receivers) specify the PPS output as
within 1uS but does that mean it wanders around over say 12 or 24
hours within 1uS of GPS Time or does it mean something else? I can
easily see the granularity of the PPS output but that is obviously not
what the specification refers to.
I guess I need to pickup a real timing receiver or good oscillator to
run a comparison with to see what is going on.
I haven't looked often, or in great detail, or logged results, but my 18x
and 18x LVC seem to be very similar in its offset from the rest such as
U-blox 6M, 6T, Sure, Adafruit etc. I.e. well within 100 ns. Causal test,
others may have measured more accurately. I've not seen any 1 microsecond
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Email: david-taylor at blueyonder.co.uk
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