[ntp:questions] NMEA ref.clock better than my ISP's timeserver?
David J Taylor
david-taylor at blueyonder.not-this-part.nor-this.co.uk.invalid
Fri Jun 12 08:59:38 UTC 2009
> The nmea is virtually useless for accurate timing. The main thing that
> the unit gives you is the PPS. You have to makes sure you do not
> degrade it.
The GPS 18x LVC only claims an accuracy of one microsecond for PPS in the
first place. The RS-232 receivers may well have some filtering limiting
the risetime to a couple of microseconds (i.e. good enough for the maximum
baud rate, typically 115,200 baud), so even if the final risetime after
the cable is a microsoecond or so, that's not going to degrade the
accuracy signifcantly for normal use. Not an issue.
>>> I'm not sure whether the NMEA driver attempts to send anything /to/
> Which NMEA driver?
The one in NTP, which would work with the GPS 18x LVC.
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