[time-nuts] Serial port splitter s/w

[David J Taylor]

A number of people have reported issues with the Raspberry Pi Ethernet 
hardware when used for NTP, as it is actually a USB-Ethernet bridge and the 
drivers may not be all they could be. I have not had problems myself but I 
do not run NTP on it.
The Beaglebone Black (BBB) is supposed to be better in that regard since the 
Ethernet MAC is directly on the CPU. The BBB is also entirely open source, 
unlike the proprietary Broadcom CPU on the RPi.

Didier KO4BB
============================================

Didier,

Here are the results I saw when using Ethernet sync for NTP on a Raspberry 
Pi:

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

Syncing just from my Cable Modem WAN connection it's quite bad (offsets +/- 
3 milliseconds), but when syncing to local stratum-1 servers the offsets 
were reduced to something slightly in excess of +/- 20 microseconds.  Adding 
PPS reduces that to a couple of microseconds (with Linux 3.6.11 compiled as 
a non-tickless system) as seen further down under the "Current performance" 
heading.

Perhaps there are equivalent graphs for the BBB system somewhere?

The Raspberry Pi is sufficiently open that you can recompile programs, and 
even recompile the kernel for it.

73,
David GM8ARV
-- 
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk