[ntp:questions] best gps receiver for time synchronization
martin.burnicki at meinberg.de
Wed Mar 11 10:37:39 UTC 2009
Terje Mathisen <"terje.mathisen at tmsw.no"> wrote:
> Martin Burnicki wrote:
>> Agreed, too. However, if we are discussing about Garmins with 50 ns
>> accuracy then 1000 ns delay is magnitudes worse.
> Garmins never give better than about 1000 ns, i.e. 1 us.
>> Also, PPS pulses must not necessarily be used only as PPS signals for
>> computers. We have also applications where just a piece of hardware is
>> synchronized by a PPS signal, in which case 1 microsecond *is* relevant.
> The gold standard seems to be the Oncore timing receivers, they give you
> a PPS signal accurate to 100 ns: This is the best they _can_ do since
> the PPS signal has to be synchronized to an edge of the internal 10 MHz
> For use with NTP we do much better however, since the Oncore knows
> exactly how far off the PPS signal is from the true point, and this info
> si sent as part of the serial port signal (the "sawtooth correction"),
> giving a real measured accuracy in the 15-35 ns range, depending upon
> the model.
OK, I should have written "Oncore" instead of "Garmin".
Thanks for the details.
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