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

Unruh unruh-spam at physics.ubc.ca
Wed May 27 20:32:30 UTC 2009


pisteoff at start.no writes:

>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. :)

Probably better than 10 microseconds from the PPS if you had a decent
operating system (eg BSD or Linux) On windows, maybe 1 msec accuracy.\. 

Note that my checking with something in germany is not going to give me
very good timing. the earth is a large place. 





>Cheers,
>Geir F




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