[ntp:questions] Re: Garmin GPS18USB and NTP on Win2k

Steve Kostecke kostecke at ntp.isc.org
Sun Jun 26 04:34:26 UTC 2005


On 2005-06-26, Brad Knowles <brad at stop.mail-abuse.org> wrote:

> At 6:32 PM -0400 2005-06-25, Richard B. Gilbert wrote:
>
>>  USB does work well for navigation but I would not use it for timing.
>
> And I'm not sure that this particular model of GPS device is good
> for timing use even if the USB interface didn't add its own set of
> problems.

The GPS-18LVC provides a PPS output with a claimed accuracy of 1us.

Mine usually produces results like this (summarized w/ peer.awk):

       ident   cnt     mean   rms    max   delay    dist   disp
===============================================================
127.127.20.0   5235  -0.000  0.003  0.014  0.000   0.270  0.248
127.127.7.0     172  -0.467  0.418  2.435  0.000  26.100  3.086

(127.127.20.0 == GPS_NMEA, 127.127.7.0  == CHU_AUDIO)

Not bad for an $80 (including delivery) GPS that only sees about half of
the sky.

-- 
Steve Kostecke <kostecke at ntp.isc.org>
NTP Public Services Project - http://ntp.isc.org/



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