[ntp:questions] SNTP with 1ms of precision?
Richard B. Gilbert
rgilbert88 at comcast.net
Fri Jun 18 16:55:13 UTC 2010
David J Taylor wrote:
> "Richard B. Gilbert" <rgilbert88 at comcast.net> wrote in message
> news:fcGdnXzbxfVY7IfRnZ2dnUVZ_sadnZ2d at giganews.com...
>> If you have a GPS timing receiver (different from navigation
>> receiver), with a PPS output, one edge of that pulse should be
>> accurate to within 50 nanoseconds. A serial output will tell you
>> which second is marked by the pulse.
> .. although the very popular GPS 18x LVC specifies:
> "Accuracy: Measurement Pulse Output Time: +/- 1 microsecond at [the]
> rising edge of the pulse."
> so not quite as good as 50 nanoseconds.
The difference is not significant unless you can somehow take advantage
of the greater accuracy! The difference in price between the Motorola
device whose specifications I was citing and the GPS 18x LVC is quite
significant; ISTR that I paid about $300 for mine. If I had to replace
it, I'd go with the GPS 18X LVC.
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