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[gpsd-users] Usind gpsd as ntpd source without PPS

From: Henrik Bieler
Subject: [gpsd-users] Usind gpsd as ntpd source without PPS
Date: Thu, 25 Feb 2016 15:32:30 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1


I am running gpsd on a RaspberryPi which has no connection to the Internet.
I would like to set systemtime based on gps time.
I don't need the precicision of PPS, and I doubt that my GPS supports it.

gpsd version 3.11
ntpd version 4.2.6p5
Raspbian Jessie

I tried to follow the instructions layed out in
gpsd-time-service-howto.txt contained in the gpsd source.

I am using segment 2. To avoid permission trouble.

ntp.conf :
server minpoll 4 maxpoll 4
fudge time1 0.535 refid GPS

ipcs -m :
key        shmid      owner      perms      bytes      nattch     status

0x4e545030 294912     root       600        80         1

0x4e545031 327681     root       600        80         1

0x4e545032 360450     root       666        80         2

0x4e545033 393219     root       666        80         1

0x47505344 131076     root       666        31616      1

looks ok. I can see ntpd and gpsd attached.
The gpsd has 3D fix and correct time (cgps)

When started in debug mode I can see gpsd not writing anything to the
shared memory. See attached logs. (One with ublox driver, one forcing
nmea driver)

Base on line 250 in timehint.c I think I should see gpsd writing to
shared memory in the logs.
But it does not show up in the logs. So I guess gpsd is not writing to
shared memory.
I suspect that gpsd might wait for a valid PPS signal (which I don't
have) before writing anything (even NMEA Time) to shared memory.

Maybe this is a bug? Or a feature.. that I would like to disable...

Your help in getting this to work is highly appreciated. :-)


Attachment: gpsdlog_nmea.txt
Description: Text document

Attachment: gpsdlog_ublox.txt
Description: Text document

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