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

David J Taylor david-taylor at blueyonder.co.uk.invalid
Tue Mar 6 19:30:41 UTC 2012


"unruh" <unruh at invalid.ca> wrote in message 
news:Obt5r.32277$HR6.15856 at newsfe21.iad...
[]
> Since a 1 second error in nmea would also impact the PPS output, his
> observation is far from irrelevant. That was what happened with the
> Garmin 18x-- the nmea offset became greater than a second, and all hell
> broke out.

So you agree with me, that the NMEA output is not to be trusted.  However, 
it should not be an issue in a GPS designed and specified for timing 
purposes, and working to specification.

But Ron's BU-353 GPS is not designed for timing, and there is no 
specification on the datasheet saying when the sentences are output 
relative to the second edge.  The device has /no/ PPS output.  It is 
unsuitable for NTP.

David 



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