[ntp:questions] NMEA ref.clock better than my ISP's timeserver?

David J Taylor david-taylor at blueyonder.not-this-part.nor-this.co.uk.invalid
Wed May 27 19:21:28 UTC 2009

pisteoff at start.no wrote:
> After first trying the Haicom HI-204III claiming to have PPS in the
> manual without really having it, I bought a Garmin 18x LVC and
> connected it to the onboard COM-port (COM1) on my Asus M3N78 PRO
> mainboard. The Haicom is residing on a USB serial adapter (COM6) to
> check how stable the offset is.
> Running ntp4.2.5p175-win-x86-bin configured with a couple of
> timesources it seems like my ISP's NTP-server gets "disqualified".
> Before setting up my own ref.clock I used to have ntp.online.no as my
> "favorite NTP-server" thinking it would be the best / most local
> server, but now I might offer them to use me as a clock-source? ;)
> Anyone wishing to see on their own, might check with ntpq
> solbakken.dyndns.org   What kind of accuracy is expectable with a NMEA
> GPS with PPS connected to the DCD-line of the serial port? It's not
> that I have any special need for extreme accuracy, but I suppose it's
> allright having the most accurate clock in the neighborhood. :)
> Cheers,
> Geir F


I typically see an offset within 0.2 milliseconds using a direct 


With USB I would see within about 0.5 milliseconds.

Both are much better than an Internet-based time source.

Your Haicom has an offset of nearly 0.5s, suggesting that you might be 
using the wrong edge of the PPS signal.


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