[ntp:questions] NMEA refclock questions: baud-rate and PPS

David J Taylor david-taylor at blueyonder.co.not-this-bit.nor-this-part.uk.invalid
Sat Jan 28 14:56:44 UTC 2006


Folks, I'm thinking of adding my new Garmin GPS 18 LVC just to see how 
well it might function with serial input alone, so I have some questions.

With the NMEA refclock driver (type 20):

- is it possible to select the baud rate without re-compiling or must it 
be 4800?  I would have thought that having the higher baud rate might 
perhaps improve jitter.

- is a PPS signal actually required, or will the driver function with just 
the serial input (I realise that accuracy will be much worse without the 
PPS, but his is just for testing).

- is it possible to use NTP just to observe a refclock, without actually 
syncing time with it?

Thanks,
David 





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