[ntp:questions] How to debug GPS PPS?

Thomas Laus lausts at acm.org
Tue Mar 9 14:07:46 UTC 2010


On 2010-03-09, xyz-2041 <xyz2041 at gmail.com> wrote:
> Forgot to add the changes to /etc/ntp.conf:
>
> Thanks Tom, et. al. for helping me get this going.
> The box is now running as Stratum 1.
>
> # Links for NTP Oncore GPS(0)
> link cuad0 pps0
> link cuad0 oncore.pps.0
> link cuad0 oncore.serial.0
>
>  Added a 2nd group:
>
>   # GPS Oncore driver 0
>   server 127.127.30.0
>   fudge  127.127.30.0   refid GPS0
>
>   # PPS driver:
>   server 127.127.22.0
>   fudge  127.127.22.0   refid PPS0
>
> # ntpq -c pe
>      remote           refid      st t when poll reach   delay
> offset  jitter
>==============================================================================
>  GPS_ONCORE(0)   .GPS.            0 l    -   16    0    0.000
> 0.000   0.000
>  PPS(0)          .PPS.            0 l    -   64    0    0.000
> 0.000   0.000
> oGPS_ONCORE(1)   .GPS.            0 l    5   16  377    0.000
> -0.001   0.002
> xPPS(1)          .PPS.            0 l   53   64  377    0.000
> -0.001   0.002
>  192.168.2.255   .BCST.          16 u    -   64    0    0.000
> 0.000   0.002
>
The Oncore 0 and PPS 0 entries are not doing anything for your ntp
installation.  They both show a '0' in the reach column.  This means
that NTP is not using either of those two devices for timekeeping.  You
can delete them from your configuration files.  You are also not getting
any benefit from your broadcast client.  There are many references in
the NTP Documenatiuon about broadcast client configuration, especially
in the area of authentication and key exchange.  I hope that you also
include some Internet timeservers in your installation to check the
sanity of your GPS clock.  The recomendation is to have at least 4 time
sources, including your GPS clock.  That lets the majority outvote a
'falseticker'.

Tom

-- 
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PGP KeyID = 0x5F22FDC1
GnuPG KeyID = 0x620836CF




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