[ntp:questions] NTP sever on an isolated Network

Diego Ramos leituras at gmail.com
Sat Jan 10 00:38:11 UTC 2009


All right. I'll show those options to my manager, but I think he will prefer
the USB Option as we don't need to be extremely accurate.

Once more, I'm really glad for all the help I'm getting here. I'm stuck with
this problem for a long time and the help I got here saved me a lot of days.

Thanks a lot.

Diego

On Fri, Jan 9, 2009 at 10:22 PM, Unruh <unruh-spam at physics.ubc.ca> wrote:

> leituras at gmail.com (Diego Ramos) writes:
>
> >> To sync to a second any gps receiver will do. The Garmin 18PC or USB
> will
> >> do  and will get you down to about 5ms accuracy with some tuning. The
> PPS
> >>  on the 18LVC will do 1000 times better ( again $50-100 range)
> >>
> >> On the 18PC you have to supply the, I think it is 12 V from somewhere
> else.
> >> On the USB it will supply its own voltage if I read correctly.
> >>
> >>
> >But I'll be able to use the Garmin 18 USB and xntpd? Which refclock I'll
> >use?
>
> nmea
>
> The gps nmea signal message includes the time. It takes about 200ms for
> that nmea sentence to be sent, but that can be roughly  zeroed out by an
> appropriate
> fudge to the nmea driver in the ntp.conf file. The usb port  is a bit
> flakey in its timing etc, but that will onely be a few millisec. Thus if
> you are happy with 5ms or so, the nmea driver and the GPS usb should be
> fine. (someone may have done it so could refine that 5 ms figure to be an
> accurate estimate of the time error you could get.) It is certainly much
> better than 100ms (1/10)
>
> Why use xntpd? That is ancient.  Use the latest ntpd 4.2.4p6
>
>
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