[ntp:questions] SIRF time output wobble, GPS or NTP fault?

David J Taylor david-taylor at blueyonder.co.uk.invalid
Wed Mar 7 08:51:58 UTC 2012

> Are there any NMEA GPS that are designed for timing? Maybe - but I
> can't think of one right now.

GPS 18x LVC has both NMEA and PPS.  Is it "designed for timing" in that 
case?  Perhaps not, as it doesn't have the sawtooth data which some 
devices offer.  Is its 1 microsecond accuracy good enough?  Plenty good 
enough for most NTP uses, I think.

> I think the GPS could be working within its specs and still be as far
> off as was reported.   The spec only requires that NMEA data to be
> output within the second to which they apply.  The worst case reported
> error as about 0.9 seconds which is within spec.
> Chris Albertson
> Redondo Beach, California

NMEA out to be started or complete within the second?


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