[time-nuts] An embedded NTP server

David J Taylor david-taylor at blueyonder.co.uk
Wed Jan 2 20:05:45 UTC 2013


From: James Harrison
[]
This is exactly what I've done using the Raspberry Pi (Broadcom ARM
SOC running Linux) and a GPS module with the PPS kernel hook for Linux
GPIO. Still a beginner/aspiring time-nut so I'm not sure on accuracy
(PLL offset jitter suggests ~5-10ms worst-case but I've not looked
much into measuring it yet), but it's an improvement on internet NTP
at least.

(Brief writeup here:
http://www.talkunafraid.co.uk/2012/12/the-ntpi-accurate-time-with-a-raspberry-pi-and-venus638flpx/
- - be gentle, it's my first 'real' timing project!)

James
============================================

James,

You might be interested in my write-up:

  http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html

and its performance:

  http://www.satsignal.eu/mrtg/performance_ntp.php

I was playing with RasPi-1 today to see whether a different (navigation) GPS 
receiver or system configuration would make any difference to the 
oscillatory nature of the offset, hence the big step around 11:00 when the 
card was restarted after an hour's power down.  RasPi-2 with a timing GPS 
receiver looks better, and it should have an identical configuration to 
RasPi-1 (except that the USB port is being sent data).

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




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