[ntp:questions] First attempt GPSD/PPS ->NTP time server

David Woolley david at ex.djwhome.demon.co.uk.invalid
Sun Jan 27 09:25:32 UTC 2008


Unruh wrote:
> 
> He was refering solely to the NMEA signal not the PPS. Some GPS receovers
> have no pps.

In general those are not suited to accurate time transfer, and ones with 
PPS cost a lot less than the the commodity car navigation devices, 
because they don't have loads of map data (the price difference is 
probably more in the US than the UK, though).  The de facto standard for 
cheap GPS time sources is the Garmin GPS 18 LVC, which was about USD 60 
or GBP 60 when I did a not very thorough search, recently.

> 
> I am afraid I simply do not believe this. NMEA is lucky to get a ms not a
> usec. The offset on the NMEA should be a lot bigger than .001

The clock driver is not reporting the time the NMEA sentence arrived, 
but rather the PPS time for that sentence.




More information about the questions mailing list