[ntp:questions] best gps receiver for time synchronization

Richard B. Gilbert rgilbert88 at comcast.net
Mon Mar 9 21:23:36 UTC 2009

jack wrote:
> Hi all,
> I am trying to sync my Windows box to an external GPS source. I
> currently have BU353, whose output is not very periodic. I read up on
> ntpd implementation that uses PPS signal but I don't even have an RS
> 232 port on my computer.
> My questions:
> 1) what's the best GPS antenna (and protocol) in terms of
> consistencies in its output?
> 2) what kind of accuracy can i expect?
> Thanks to all.
> Jack

The first thing to do is to take great care to get a GPS receiver 
designed for timing service.  The output of a timing receiver is usually 
RS-232C serial plus the Pulse Per Second (PPS) output.  USB has 
unpredictable latencies that make it unsuitable for timing.

Just about any GPS timing receiver is accurate to within about 50 
nanoseconds using the PPS signal.  Getting this time into any "vanilla" 
computer is going to degrade the time by an unpredictable and difficult 
to determine amount of time.

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