[ntp:questions] Using Trimble TSIP under Linux

A C agcarver+ntp at acarver.net
Sun Oct 28 20:50:17 UTC 2012

On 10/28/2012 13:31, David Taylor wrote:
> On 28/10/2012 16:50, Rob wrote:
> []
>> Sorry I have no idea how to get it to work with a raspberry pi.
>> I think when you have to tinker with drivers anyway, it is better
>> to adapt a driver from ntpd and leave out gpsd.
>> (unless you want to use the positioning information from the receiver
>> for a local app that supports gpsd)
> Rob,
> Thanks for your comments.  I don't /need/ gpsd, but it does seem to be
> at least partially working.  I've made progress by looking at the
> various Internet sources, and found someone who had recompiled my
> version of Linux to include PPS support.  So now I can:
> - use cgps -s to see the output from the GPS via gpsd
> - configure NTP to use the type 28 driver and it sees the GPS time
> - use sudo ppstest /dev/pps0 and see assert pulses coming in
>    (the clear field is always 0 though, perhaps the 150
>     microsecond pulse is too narrow?)
> but NTP never connects to the PPS source.  My NTP configuration looks like:

If your PPS signal is on /dev/pps0 as you describe, add the ATOM driver 
(number 22) in addition to your SHM (gpsd) driver and it will be fine:

This is exactly how I have my own server running (but not on an R-pi). 
PPS comes in via one port, gpsd SHM comes in from another port and two 
drivers (22 and 28) take care of gluing them together.

> ===========================================
> driftfile /var/lib/ntp/ntp.drift
> server  minpoll 4 maxpoll 4
> fudge time1 +0.350 refid GPS  stratum 15

server  minpoll 4 maxpoll 4

> server minpoll 4 maxpoll 4 prefer
> fudge refid PPS
> server  minpoll 5 maxpoll 5  iburst prefer
> server  minpoll 5 maxpoll 5 iburst
> server  minpoll 5 maxpoll 5 iburst
> pool uk.pool.ntp.org  minpoll 10  iburst
> ===========================================

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