[time-nuts] GPS position survey

Chris Albertson albertson.chris at gmail.com
Sun May 5 11:42:12 EDT 2013

If the only use of the GPS receiver is to drive NTP, then 2,000
seconds is long enough  NTP runs at the microsecond level and the tiny
remaining error after 2000 seconds will never be noticed by NTP.
However if you are really nuts and want to do the best you can then
let it run for 12 hours.   That is one orbital period.

That said, what matters FAR more is that the antenna have a good view
of the full sky and be far away from anything that can reflect radio
waves.   This pretty much means the antenna should be on a pipe mast
on the roof. (a 3/4 inch pipe with a pipe flange on top).   If you
have not done this then don't bother with a 12 hour survey as you'd be
worrying about details that don't matter.

On Sun, May 5, 2013 at 3:35 AM, Miguel Barbosa Gonçalves <m at mbg.pt> wrote:
> Hi fellow time nuts!
> I've recently bought a Trimble Acutime gold that will be used as a
> reference clock for a NTP server.
> This receiver has the possibility of averaging it's position before
> entering what Trimble calls the overdetermined clock state. The
> default is to average the position with 2000 fixes.
> What do you believe is a good number of fixes for the survey in this case?
> Cheers,
> Miguel
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Chris Albertson
Redondo Beach, California

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