M Z wrote:
I am trying to get an independently clocked SuSE 11.2 machine based on just
GPS/PPS. I am using
gpsd 2.95 with garmin 17 serial port but also have tried this with globalsat
mr350p. gpsd/cgps shows 3D
signal lock. ntpq Ver. 4.2.6p2
*** HERE IS THE PROBLEM/Question ***
When I have an outside source, like 0.us.pool.ntp.org or tick.usask.ca, ntp uses
the PPS signal perfectly. When I drop the outside source or substitute with
127.127.0.1,
NTP x's out my PPS and then GPS (when reach is 177) even though it is a good
signal.
How can I force ntp to use the PPS signal or at least not drop it?
************************************
clocksource is tsc which seems to work a little better (also tried hpet, same
problem)
I also tried it with none of the 'restrict' clauses and without 'disable'.
clip from ntp.conf:
#Must use disable for SuSe since the internal micro-nano timekeeping
#conflicts with ntp and causes excess jitter ( > .010 microsec ).
disable kernel
server 127.127.28.0 minpoll 4
fudge 127.127.28.0 time1 0.290 refid GPS stratum 3 #garmin
server 127.127.28.1 minpoll 4 prefer
fudge 127.127.28.1 refid PPS
Try with prefer for the refclock rather than the PPS
server 127.127.28.0 minpoll 4 prefer
and don't use 127.127.0.1
David
server tick.usask.ca iburst #stratum one canada server
driftfile /var/lib/ntp/drift/ntp.drift #(has had values from -70 to 13)
restrict -6 ::1
restrict 127.0.0.1
restrict default kod nomodify notrap nopeer noquery
restrict tick.usask.ca mask 255.255.255.255 nomodify notrap noquery
Soon after restart:
ra2:# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
+SHM(0) .GPS. 3 l 3 16 3 0.000 14.703 1.701
*SHM(1) .PPS. 0 l 2 16 3 0.000 -119.90 1.930
+tick.usask.ca .GPS. 1 u 7 64 1 92.725 -109.97 3.086
after 12+ HOURS looks good to me:
ra2:~> /usr/sbin/ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
xSHM(0) .GPS. 3 l 7 16 377 0.000 108.591 32.540
*SHM(1) .PPS. 0 l 6 16 377 0.000 0.007 0.000
xtick.usask.ca .GPS. 1 u 41 64 377 92.184 6.839 0.316
ra2:~> /usr/sbin/ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
xSHM(0) .GPS. 3 l 2 16 377 0.000 62.204 24.780
*SHM(1) .PPS. 0 l 1 16 377 0.000 0.007 0.000
+tick.usask.ca .GPS. 1 u 3 64 377 92.184 6.839 0.318
ra2:~> /usr/sbin/ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
xSHM(0) .GPS. 3 l 15 16 377 0.000 83.603 17.002
*SHM(1) .PPS. 0 l 14 16 377 0.000 0.009 0.001
xtick.usask.ca .GPS. 1 u 48 64 377 92.184 6.839 0.318
So, to run without external sources I run both without and with localclock:
without 127.127.1.0 (SHM (GPS/PPS) only):
ra2:# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
xSHM(0) .GPS. 3 l 13 16 177 0.000 122.103 6.617
xSHM(1) .PPS. 0 l 12 16 177 0.000 -0.113 0.153
ra2:# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
xSHM(0) .GPS. 3 l 7 16 377 0.000 112.004 10.735
xSHM(1) .PPS. 0 l 6 16 377 0.000 -0.186 0.018
ra2:# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
xSHM(0) .GPS. 3 l 11 16 377 0.000 23.303 11.474
xSHM(1) .PPS. 0 l 10 16 377 0.000 -114.74 2.993
# With localclock
# LCL is unsynchronized
server 127.127.1.0 minpoll 8
fudge 127.127.1.0 refid clk_internal stratum 15
ra2:# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
xSHM(0) .GPS. 3 l 11 16 177 0.000 75.604 25.541
*SHM(1) .PPS. 0 l 10 16 177 0.000 -0.119 0.136
LOCAL(0) .clk_. 15 l - 256 0 0.000 0.000 0.000
ra2:# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
xSHM(0) .GPS. 3 l 4 16 377 0.000 67.604 30.856
xSHM(1) .PPS. 0 l 3 16 377 0.000 -0.107 0.124
LOCAL(0) .clk_. 15 l - 256 0 0.000 0.000 0.000
ra2:# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
xSHM(0) .GPS. 3 l 2 16 377 0.000 58.803 8.170
xSHM(1) .PPS. 0 l 1 16 377 0.000 0.077 0.014
*LOCAL(0) .clk_. 15 l 32 256 7 0.000 0.000 0.000
using ntpd -ddd there are some early lines:
select: survivor 127.127.28.1 5.291672
select: survivor 127.127.28.0 8.291827
select: combine offset -0.047243999 jitter 0.000000477
event at 2 SHM(1) 963a 8a sys_peer
but then later:
select: survivor 127.127.28.0 3.057312
select: combine offset 0.087603614 jitter 0.021384352
event at 97 SHM(0) 961a 8a sys_peer
and then no survivors at all:
event at 98 0.0.0.0 0418 08 no_sys_peer
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