[ntp:questions] GPS_NEMA, but high offset and jitter?

Kelsey Cummings kgc at microshaft.org
Mon Mar 1 04:53:22 UTC 2010


David J Taylor wrote:
...
> I would knock something up if there were enough interest, but it would
> be a Windows program so of limited interest to the OP.

That's the idea anyway.  At the time, I was convinced the PPS signal was
showing clearly and it was but with the led transistor in backwards the
PPS line was getting pulled down to 1.4v or thereabouts.  Not enough for
the serial port to register it.  It would have been useful to have
something that just watched for the DCD pulse rather than trying to
figure out what nptd was or was not seeing.

With that fixed, everything synced right up.  Seems reasonably stable
with jitter at 4ms and offset fluctuating from -4ms to 4ms.  More than
good enough for our needs.

-K




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