[ntp:questions] Re: ntpd/GPS on Sun: newbie questions

Jonathan jonathanNOFISH at sprintmail.com
Thu Jan 1 19:16:48 UTC 2004

"Allen McIntosh" <mcintosh at nospam.com> wrote in message
news:bsvkr1$t37$1 at mc-pc.research.telcordia.com...
> In article <_bednQmjsfyZr26iXTWc-g at speakeasy.net>,
> Jonathan <jonathanNOFISH at sprintmail.com> wrote:
> >1)  Can the xntpd from Solaris 8+patch 109667-05 (v3-5.93e) support NMEA
> >receivers?  It did not seem to work at all when I tried it; only 4.1.1a
> >worked.
> If the Solaris xntpd contains the string "NMEA GPS Clock", then yes.
> If not, then probably not.  (strings xntpd | grep "NMEA")

Hmmm, the binary does contain that string, exactly.  However xntpd seemed to
be ignoring the NMEA strings coming from the GPS and never syncs with it,
whereas ntpd (4.1.1a) syncs with the GPS in about 3 minutes if the GPS has
position lock.

> >2)  What NMEA strings are required/supported in (x)ntpd?  The Sony
> >supports $GPRMC, $GPGGA, $GPGLL, and $GPZDA, which I think some or all
> >supported by (x)ntpd?
> It's in the comment at the start of refclock_nmea.c.

Thanks, I'll check the source.

> >3)  Does (x)ntpd rely purely on NMEA data for accurate timekeeping?  I
> >some posts related to people using PPS with GPS units but I'm not sure I
> >understand the connection yet.
> As I understand it, the timing on NMEA sentences is significantly sloppier
> than the PPS signal.

It sounds like that is definitely the case, however it's going to be the
only option with this Radio Shack model, as it doesn't seem to be very

Thanks for the info.

More information about the questions mailing list