On 2011-08-25, Rob <[email protected]> wrote: > unruh <[email protected]> wrote: >>> any sense to me. Perhaps you meant the NMEA sentence used >>> needed to be within .5 sec but again that doesn't make a >>> lot of sense in practice as all three different gps units >>> I've used each have large variations in NMEA time so >>> require both fudge factor and increase in the range of >>> values that will be accepted. >> >> Nope, I meant that system time should be within .4 sec. That will not >> matter if you use gpsd since that should accurately get the time of the >> pps pulse from the nmea of the gps unit (assuming it is not broken like >> some of the garmin 18x are). > > What happens with gpsd is completely unrelated to what happens when > you use ntpd's own NMEA and PPS support. > > When you have experienced that you should be within .4 sec before PPS > works when using gpsd, you should not project that onto ntpd and its > PPS support. The .4 sec check is within gpsd.
>From refclock_atom.c ... * Before this driver becomes active, the local clock must be set to * within +-0.4 s by another means, such as a radio clock or NTP * itself. There are two ways to connect the PPS signal, normally at TT .... _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
