[time-nuts] GPS message jitter (was GPS for Nixie Clock)

David J Taylor david-taylor at blueyonder.co.uk
Tue Jul 19 04:25:13 EDT 2016

From: Scott Stobbe

I am happy to hear you issue was resolved. What I meant to say is the
problem could also be mitigated using the UART's flow control, this could
be done by the original GPS designers or by an end user if the CTS line is
pined out. Gating the UART with a conservative delay, say 500 ms from the
time mark or PPS signal. The serial string would just sit in the transmit
buffer until the fixed delay expires and the UART starts transmitting.

It was a Garmin problem, and they released updated firmware after some 

Again, it's nothing to do with serial communication, but CPU loading.

Many GPS devices can only just send the default information at default speed 
(typically 4800/9600), so the UART would need quite a lot of buffering for 
such a scheme to work.  For any serious use, the PPS line is the way to go.

SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk
Twitter: @gm8arv 

More information about the time-nuts mailing list