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Re: [gpsd-dev] U-Blox M8, PPS and NTPsec - GPSd logic enhancement


From: Martin Boissonneault
Subject: Re: [gpsd-dev] U-Blox M8, PPS and NTPsec - GPSd logic enhancement
Date: Fri, 5 Apr 2019 13:34:16 -0400
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1

Hi Gary!

On 2019-04-03 19:54, Gary E. Miller wrote:
Yo Martin!

On Wed, 3 Apr 2019 18:28:00 -0400
Martin Boissonneault <address@hidden> wrote:
   From what I observed, sometimes GPSd seems to associate the PPS to 
the wrong timestamp and that would  confuse NTPd.
Now that is unusual.  At least native gpsd.  As long as your RasPi has
other network chimers that should never happen.  It can happen when you
have a voltage mismatch on PPS line, or large CPU load.

  It just happened on restart of both GPSd and NTPsec. After a while, it corrected itself without intervention.

u-Blox M8 SPG 3.01, serial at 115200, PPS on Raspberry Pi 3B+ GPIO.
Linux rPi 4.14.98-v7-mbt #3 SMP Sun Feb 24 00:02:35 EST 2019 armv7l GNU/Linux
gpsd: 3.18.1 (revision 3.18.1)
ntpd ntpsec-1.1.3+ 2019-04-02T18:41:39Z (git rev 666fa4784).

  Active messages:

  • UBX TIM-TP
  • UBX NAV-SOL
  • UBX NAV-SVINFO
  • UBX NAV-TIMEGPS
  • UBX NAV-TIMEUTC

I will disable the unused messages TIM-TP, NAV-TIMExx in the mean time...

If I can be of assistance for debugging this, just ask. I'll do my best to assist.

Thanks,
Martin


--ntpshmmon while 1s off (taken within a few seconds):
sample NTP2 1554482338.001854112 1554482337.999994280 1554482339.000000000 0 -30
sample NTP0 1554482338.063477471 1554482338.063415075 1554482339.000000000 0 -20
sample NTP2 1554482339.000152349 1554482338.999994538 1554482340.000000000 0 -30
sample NTP0 1554482339.066024430 1554482339.065656464 1554482340.000000000 0 -20

--ntpshmmon after it became right:
sample NTP2 1554483556.001875133 1554483556.000000299 1554483556.000000000 0 -30
sample NTP0 1554483556.066742535 1554483556.066708941 1554483556.000000000 0 -20
sample NTP0 1554483556.069029030 1554483556.068777886 1554483556.000100851 0 -20
sample NTP2 1554483557.000244436 1554483556.999999957 1554483557.000000000 0 -30
sample NTP0 1554483557.064360119 1554483557.063462729 1554483557.000000000 0 -20
sample NTP0 1554483557.066639636 1554483557.065528966 1554483557.000101089 0 -20

-- Script:
echo ...Stopping services
sudo systemctl stop ntpd.service
sudo systemctl stop gpsd.service

echo ...Starting services
sudo systemctl start gpsd.service
sudo systemctl start ntpd.service

--ntpmon while 1s off:
     remote           refid      st t when poll reach   delay   offset   jitter
 SHM(1)          .gPPS.           0 l    -    1    0   0.0000   0.0000   0.0010
*SHM(2)          .gPPS.           0 l    -    1  377   0.0000 1000.006   0.0001
 win7mbt-lt_eth. .STEP.          16 u    -   32    0   0.0000   0.0000   0.0010
 lenovowin7-pc_e 192.168.10.101   4 u   21   32   37   0.4961 997.8945   0.3195
+time12.nrc.ca   132.246.11.231   2 u   66   64    3   7.1812 1000.391   0.2640
+time1.chu.nrc.c 209.87.233.52    2 u   64   64    3  47.1171 993.3865   6.7573
 ca.pool.ntp.org .POOL.          16 p    -  256    0   0.0000   0.0000   0.0010
 us.pool.ntp.org .POOL.          16 p    -  256    0   0.0000   0.0000   0.0010
 north-america.p .POOL.          16 p    -  256    0   0.0000   0.0000   0.0010
 planefinder.poo .POOL.          16 p    -   64    0   0.0000   0.0000   0.0010
+comet.spiderspa 213.251.128.249  2 u   32   64    7   4.7819 1000.208   0.3220
+muug.ca         200.98.196.212   2 u   28   64    7  36.3342 998.1695   0.4170
+ntp3.torix.ca   .PTP0.           1 u   31   64    7  10.3596 1000.194   0.6505
+ipagstaticip-ba .PPS.            1 u   28   64    7  14.7129 1000.279   0.4130
#ec.sedley.net   78.141.31.73     4 u   27   64    7  18.5554 1010.428   0.3481
#blue.1e400.net  45.79.111.167    3 u   29   64    7  12.5464 998.4322   0.4586
+dns-e.wdc-us.ho 129.6.15.30      2 u   30   64    7  22.0006 998.9929   0.5643
#107.181.191.189 40.139.41.69     2 u   29   64    7  77.8039 1008.270   0.5252
+h199-182-204-19 111.196.98.82    2 u   31   64    7  76.9276 1004.539   0.4968
#69.10.161.7     195.205.216.85   3 u   27   64    7  97.6837 1007.970   0.3375
+nu.binary.net   204.9.54.119     2 u   25   64    7  37.8393 1000.988   0.4036
+anaheim.capsaic 243.50.127.182   2 u   25   64    7  56.4148 1003.702   0.3550
ntpd ntpsec-1.1.3+ 2019-04-02T18:41:39Z        Updated: 2019-04-05T12:38:16 (1)

--ntp.conf extract:
# GPS PPS reference (GNSS PPS), only one of two will be present.
refclock shm unit 1 refid gPPS minpoll 0 maxpoll 8 prefer
refclock shm unit 2 refid gPPS minpoll 0 maxpoll 8 prefer

# LAN servers:
server 192.168.10.10 iburst maxpoll 5

server 192.168.10.11 iburst maxpoll 5 prefer

# Government NTP reference servers - Stratum 2:
server time.nrc.ca iburst prefer

server time.chu.nrc.ca iburst prefer

# Pool:
pool ca.pool.ntp.org iburst
pool us.pool.ntp.org iburst
pool north-america.pool.ntp.org iburst
#pool pool.ntp.org iburst

#pool debian.pool.ntp.org iburst
pool planefinder.pool.ntp.org iburst


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