[ntp:questions] ntp on ubuntu 12.10 with gps and pps.

David Taylor david-taylor at blueyonder.co.uk.invalid
Sun Apr 7 13:46:03 UTC 2013

On 07/04/2013 11:14, Paul J R wrote:
> Hi All,
> I've got a SiRF star 3 GPS with a PPS line which im trying to get
> running on a machine with ubuntu 12.10 and a serial port using the DCD
> line for pps signalling.
> o127.127.20.0    .GPS.            0 l    4    8  377    0.000 -0.065
> 0.003
> Seems like a pretty decent little gps unit, assuming i've got it
> functioning and configured correctly?

Just for comparison:

Intel Atom PC running FreeBSD 8.2 (Pixie):
o127.127.20.1    .PPS. offset/jitter -0.001   0.002

Two Raspberry Pis running Linux 3.2.27+
o127.127.22.0    .PPS. offset/jitter 0.002   0.002
o127.127.22.0    .PPS. offset/jitter 0.001   0.002

Raspberry Pi running Linux 3.36.11
o127.127.22.0    .PPS. offset/jitter 0.000   0.002

65 microseconds offset seems a little high to me, but the PCs I've just 
quoted are all (mostly) /only/ serving NTP.  I have been doing a little 
installation work on Raspberry Pi #3 today, and it now has a steady CPU 
and network I/O load.  Its PPS was only configured yesterday. 
Performance graphs are here:


I hope that helps your comparisons.
Web: http://www.satsignal.eu

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