[ntp:questions] Using Garmin GPS-III+ as Time source

Unruh unruh-spam at physics.ubc.ca
Sat Nov 22 19:15:43 UTC 2008

George R. Kasica <georgek at netwrx1.com> writes:


>Just curious if this is usable as an NTP time source.

>I have an old Garmin GPS-III+ lying around here (its a small handheld
>GPS unit) that I can power from an AC Adapter and get a solid GPS
>signal out of indoors actually that will provide NEMA 0183 version 2.0
>output from RS232 that I have already got a cable for.

If it provides an nema output then you probably can use it to discipline
your clock to of order 10-20ms. 

>How/can I configure ntpd to utilize this setup in linux?? Or am I
>after something that I can't do with this unit? Does someone have an
>alternative recommendation??

Plug it into the serial port and put


into /etc/ntpd.conf

If you want microsecond clock accuracy then get a gps with PPS output.
(Pulse Per Second) I am almost certain that your gps does not have this

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