[ntp:questions] Using parse driver rather then nmea driver?

Heiko Gerstung heiko.gerstung at meinberg.de
Wed Oct 22 10:20:58 UTC 2008

Another Sillyname schrieb:

> It's a shame no-one makes a GPS device that allows multiple sources at
> the same time (I suppose an old garmin GPS III plus unit with multiple
> external antennas I have might do it....if I could power it from the
> mains).

Well, we (Meinberg) have redundant GPS receivers optimized for timing and I am 
sure our competition offers something similiar. But I honestly doubt that you 
want to consider them because they are orders of magnitude more expensive than 
the B 303 GPS mouse ... and if you only need half a second of accuracy, there is 
really no point in spending the extra moneys :-)

> Any other ideas?

The parse driver has a "trust time" parameter which allows you to specify how 
long the refclock driver should continue to accept the time string after it lost 
sync. Is there something similiar in the NMEA driver?

And, you always could declare your local clock refclock to be (*gasp* *cough* 
*doublegasp*) stratum 0, an approach that leads directly into hell and will 
definitely create all sorts of trouble.

On the other hand: Did you try what happens when it looses sync? If there is no 
other source, ntpd will continue to declare itself a synchronized stratum 1 
server and only the root dispersion will increase over time.

Half a second? Wow, you should probably consider calling a self-written bash 
script that reads a time string from the unit and sets the time using "date" :-)


More information about the questions mailing list