Re: [gpsd-users] GPSD Time service

[Yakov Shmulevich]

Hi,

More information corresponding this issue:

I don't need to restart ntpd. It is enough to disconnect the device from the internet and after short time the ntpd stop synchronization on 1PPS.

Thanks,

Yakov

On Sun, Mar 30, 2014 at 1:26 PM, Yakov Shmulevich <address@hidden> wrote:

Hi,

I have GPS receiver with 1PPS signal and am trying to use it as time source (Stratum 0) for ntpd.

For this I run gpsd with "-n" options and define the follow in ntp.conf:

server 127.127.28.1 minpoll 4 maxpoll 4 prefer

fudge 127.127.28.1 refid PPS

server 127.127.28.0 minpoll 4 maxpoll 4

fudge 127.127.28.0 time1 0.183 refid GPS

also in ntp.conf are defined public servers:

server 0.centos.pool.ntp.org

server 1.centos.pool.ntp.org

server 2.centos.pool.ntp.org

It runs without problem and I get the follow results from "ntpq -p" command:

address@hidden ~]# ntpq -p

     remote           refid      st t when poll reach   delay   offset  jitter

==============================================================================

*SHM(1)          .PPS.            0 l    6   16  377    0.000  -89.487   1.608

+SHM(0)          .GPS.            0 l    4   16  377    0.000  -22.567   2.871

+mivzakim.net    132.163.4.101    2 u   48   64  377    8.492  -93.411   3.055

 LOCAL(0)        .LOCL.          10 l   51   64  377    0.000    0.000   0.001

So, the ntpd select 1PPS as a time source.

But, if I disconnect my device from the LAN, so it has not access to remote time servers and restart ntpd, it can not synchronized on 1PPS:

address@hidden ~]# ntpq -p

     remote           refid      st t when poll reach   delay   offset  jitter

==============================================================================

xSHM(1)          .PPS.            0 l   18   16  177    0.000  -128.80  17.096

xSHM(0)          .GPS.            0 l    6   16  377    0.000  -64.392  18.757

*LOCAL(0)        .LOCL.          10 l   59   64   17    0.000    0.000   0.001

What may be a problem?

Thanks,

Yakov