On 10/28/2012 4:33 PM, 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:
===========================================
driftfile /var/lib/ntp/ntp.drift
server 127.127.28.0 minpoll 4 maxpoll 4
fudge 127.127.28.0 time1 +0.350 refid GPS stratum 15
server 127.127.28.1 minpoll 4 maxpoll 4 prefer
fudge 127.127.28.1 refid PPS
server 192.168.0.3 minpoll 5 maxpoll 5 iburst prefer
server 192.168.0.2 minpoll 5 maxpoll 5 iburst
server 192.168.0.7 minpoll 5 maxpoll 5 iburst
pool uk.pool.ntp.org minpoll 10 iburst
===========================================
With apologies for the wrap:
C:\Users\David>ntpq -p 192.168.0.14
remote refid st t when poll reach delay offset
jitter
==============================================================================
xSHM(0) .GPS. 15 l 6 16 377 0.000 5.971
2.103
SHM(1) .PPS. 0 l - 16 0 0.000 0.000
0.000
*pixie .PPS. 1 u 6 32 377 0.495 0.041
0.035
+FEENIX .PPS. 1 u 8 32 377 0.590 0.040
0.025
+Stamsund .PPS. 1 u 7 32 377 0.466 0.096
0.030
-server1.terrybu 158.43.192.66 2 u 631 1024 3 21.385 0.887
2.009
-rilynn.me.uk 193.62.22.82 2 u 601 1024 3 27.880 -0.849
6.440
-ntp0.sccis.net 193.62.22.74 2 u 612 1024 3 18.947 1.405
4.130
resntp-b-vip.lo .INIT. 16 u - 1024 0 0.000 0.000
0.000
C:\Users\David>ntpq -c rv 192.168.0.14
associd=0 status=0615 leap_none, sync_ntp, 1 event, clock_sync,
version="ntpd [email protected] Fri May 18 20:30:57 UTC 2012 (1)",
processor="armv6l", system="Linux/3.2.27-pps-g965b922-dirty", leap=00,
stratum=2, precision=-20, rootdelay=0.490, rootdisp=2.540,
refid=192.168.0.3,
reftime=d438146b.2b1fe219 Sun, Oct 28 2012 20:30:35.168,
clock=d438146f.b3c26062 Sun, Oct 28 2012 20:30:39.702, peer=22812, tc=5,
mintc=3, offset=0.042, frequency=-44.915, sys_jitter=0.034,
clk_jitter=2.397, clk_wander=0.238
I can't see anything obviously wrong, but perhaps I'm over-tired after a
day or two trying to get this working!
Lose the "minpoll 4 maxpoll 4 "!
It may not be causing your problems but but I doubt that it's
helping matters any!
The NTP software should pick the best clock(s) from those offered!
NTPD will adjust the polling intervals to suit the current
conditions. The short poll interval will correct the large errors
quickly. The longer poll intervals will be used to "fine tune".
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