Hi. I have both usglobalsat MR350P and garmin 18xLVC connected to serial at
both
4800 and 9600.
gpsd was 2.37 but is now 2.95. ntpd is 4.2.4p7, OS: SuSE 11.2 = 2.6.31. I have
used both
serial ports. I set to low_latency as per instructions:
http://www.lammertbies.nl/comm/info/GPS-time.html
gpsd 2.37 did not communicate with ntp for the pps (ntpq -p 'when' column
always
-). 2.95 seems to work ok. output looks good, xgps works (7 sats used), etc.
However, jitter seems large and offset, no matter how small to start (usually
+-
20.) always creeps up to about -300 to -500.
snip from gpsd -n -N -D 2 /dev/ttyS1
gpsd: GPS on /dev/ttyS1 is offline (0.000040 sec since data)
gpsd: GPS on /dev/ttyS1 is offline (0.000017 sec since data)
gpsd: GPS on /dev/ttyS1 is offline (0.000015 sec since data)
gpsd: PPS cycle: 1000112, duration: 960102 @ 1287118259.019369
gpsd: PPS cycle: 1000109, duration: 40007 @ 1287118259.059376
gpsd: PPS pulse rejected
gpsd: GPS on /dev/ttyS1 is offline (0.000022 sec since data)
gpsd: GPS on /dev/ttyS1 is offline (0.000021 sec since data)
gpsd: GPS on /dev/ttyS1 is offline (0.000016 sec since data)
gpsd: PPS cycle: 1000138, duration: 960131 @ 1287118260.019507
gpsd: PPS cycle: 1000128, duration: 39997 @ 1287118260.059504
gpsd: PPS pulse rejected
gpsd: unknown sentence:
"$GPGSV,3,1,11,06,27,265,21,09,36,064,34,14,53,244,29,15,06,047,25*7F\x0d\x0a"
here is snip from gpsd -D6 > file then | grep PPS
gpsd: PPS cycle: 1000327, duration: 960315 @ 1287118037.467467
gpsd: PPS cycle: 1000330, duration: 40015 @ 1287118037.507482
gpsd: PPS pulse rejected
gpsd: PPS cycle: 1000343, duration: 960328 @ 1287118038.467810
gpsd: PPS cycle: 1000348, duration: 40020 @ 1287118038.507830
gpsd: PPS pulse rejected
gpsd: PPS cycle: 1000333, duration: 960313 @ 1287118039.468143
gpsd: PPS cycle: 1000329, duration: 40016 @ 1287118039.508159
gpsd: PPS pulse rejected
ntpq -p after a long while with GPS/PPS
remote refid st t when poll reach delay offset jitter
==============================================================================
+SHM(0) .GPS. 0 l 1 16 377 0.000 -414.55 197.047
+SHM(1) .PPS. 0 l 16 16 377 0.000 -375.42 31.550
LOCAL(0) .LOCL. 10 l 24 64 377 0.000 0.000 0.001
*131.107.13.100 .ACTS. 1 u 54 64 375 55.984 -358.88 153.723
+saturn.netwrx1. .PPS. 1 u 17 64 377 64.988 -378.87 130.000
+tick.usask.ca .GPS. 1 u 54 64 377 82.113 -357.94 136.472
+216.45.57.38 209.81.9.7 2 u 15 64 377 39.344 -374.06 127.468
+thecakeisapie.n 209.81.9.7 2 u 43 64 377 10.219 -364.89 129.425
+ds3-us.zagbot.c 204.9.54.111 2 u 17 64 377 39.226 -373.65 128.148
# cat /var/lib/ntp/ntp.drift --> 158.230
ntpq -p after a couple minutes without GPS/PPS
remote refid st t when poll reach delay
offset jitter
SHM(0) .GPS. 0 l 1415 16 0 0.000 -169.04
6.823
SHM(1) .PPS. 0 l 1420 16 0 0.000 -19.507
1.432
*131.107.13.100 .ACTS. 1 u 98 128 377 55.324 -76.306 30.504
+saturn.netwrx1. .PPS. 1 u 49 128 377 61.968 -53.547 47.469
+tick.usask.ca .GPS. 1 u 207 128 376 81.499 -79.038 26.151
-dev1-c.lax009.i 209.81.9.7 2 u 52 128 377 41.986 -100.23 36.500
+clock.trit.net 192.12.19.20 2 u 35 128 377 41.783 -78.852 34.350
==============================================================================
more time
SHM(0) .GPS. 0 l 38m 16 0 0.000 0.000 0.001
SHM(1) .PPS. 0 l 38m 16 0 0.000 0.000 0.001
131.107.13.100 .ACTS. 1 u 35 64 1 63.182 -2.032 0.001
*saturn.netwrx1. .PPS. 1 u 23 64 1 59.459 -1.491 3.370
tick.usask.ca .STEP. 16 u 153 64 0 0.000 0.000 0.000
dev1-c.lax009.i 209.81.9.7 2 u 26 64 1 43.852 1.862 0.001
clock.trit.net .STEP. 16 u 103 64 0 0.000 0.000 0.001
==============================================================================
more time (+47 min)
SHM(0) .GPS. 0 l 47m 16 0 0.000 0.000 0.001
SHM(1) .PPS. 0 l 47m 16 0 0.000 0.000 0.001
+131.107.13.100 .ACTS. 1 u 15 64 373 55.200 4.175 6.996
*saturn.netwrx1. .PPS. 1 u 20 64 377 61.447 -11.922 9.974
tick.usask.ca .GPS. 1 u 64 64 15 95.860 -9.911 15.977
-dev1-c.lax009.i 209.81.9.7 2 u 9 64 377 42.149 -9.077 12.017
+clock.trit.net 192.12.19.20 2 u 36 64 377 42.041 -0.147 6.371
==============================================================================
more time
SHM(0) .GPS. 0 l 57m 16 0 0.000 0.000 0.001
SHM(1) .PPS. 0 l 57m 16 0 0.000 0.000 0.001
+131.107.13.100 .ACTS. 1 u 3 128 367 55.288 -7.875 5.460
*saturn.netwrx1. .PPS. 1 u 78 128 377 59.112 -9.368 5.779
+tick.usask.ca .GPS. 1 u 51 128 377 81.580 -7.873 1.362
+dev1-c.lax009.i 209.81.9.7 2 u 127 128 377 41.934 -6.816 3.922
-clock.trit.net 192.12.19.20 2 u 24 128 377 41.983 -13.802 4.239
just the servers are creeping a little but look like they are settling.
certainly not going to -400 like it
would already be with the PPS.
I got rid of server 127.0.0.1 in /etc/ntp.conf but that didn't help. Here is
ntp.conf:
restrict default kod nomodify notrap nopeer
restrict -6 default kod nomodify notrap nopeer
restrict 127.0.0.1
restrict -6 ::1
server 127.127.28.0 minpoll 4 maxpoll 4
fudge 127.127.28.0 time1 0.485 refid GPS
server 127.127.28.1 minpoll 4 maxpoll 4 prefer
fudge 127.127.28.1 refid PPS
server 131.107.13.100
server ntp2.netwrx1.com iburst
restrict 131.107.13.100 mask 255.255.255.255 nomodify notrap noquery
restrict ntp2.netwrx.com mask 255.255.255.255 nomodify notrap noquery
server tick.usask.ca
restrict tick.usask.ca mask 255.255.255.255 nomodify notrap noquery
server 0.us.pool.ntp.org
server 1.us.pool.ntp.org
restrict 0.us.pool.ntp.org mask 255.255.255.255 nomodify notrap noquery
restrict 1.us.pool.ntp.org mask 255.255.255.255 nomodify notrap noquery
So, what is going wrong? What things do I still need to do? This computer will
not serve time to any others but needs very accurate time itself. cron jobs all
commented out. ps ax |grep ntp looks like:
... /usr/sbin/ntpd -p /var/run/ntp/ntpd.pid -g -u ntp:ntp -i /var/lib/ntp
-c /etc/ntp.conf
Thanks.
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