[ntp:questions] How to debug GPS PPS?

Thomas Laus lausts at acm.org
Sat Jan 2 15:22:56 UTC 2010

On 2010-01-01, xyz-2041 <xyz2041 at gmail.com> wrote:
>> comunicate with your Oncore. ?You might get some insight by enabling
>> some of the statistics. ?You add them to /etc/ntp.conf
>> # NTP Statistics
>> statsdir /var/log/ntp/
>> statistics clockstats loopstats peerstats
>> filegen clockstats file clockstats type day enable
>> filegen loopstats file loopstats type day enable
>> filegen peerstats file peerstats type day enable
> OK, done:
>   cd /var/log
>   mkdir ntp
>   cd /etc
>   nano /etc/ntp.conf
> Seems to be talking to the unit:
>   http://www.A7H.com/~stuph/clockstats-Edited-2010-Jan-1-1300.txt
> Nothing in peerstats or loopstats showing anything Oncore-GPS related.
The clockstat log looks OK to me.  I see that your Oncore GT+ is
communicating via the RS-232 port on your PC.  Do you know for sure if
your GT+ has a valid almanac?  When you connect to your Oncore using
WinOncore12 under the Navigation window, does the receiver status show
that it has a 'bad almanac'?  Whenever switching mine from NMEA to
Motorola protocol, I have to reload the almanac and re-enter the
receiver information using the pushbuttons on the top.  They all seem to
init themselves in the NMEA mode, but require some manual intervention
when switching to Motorola Binary.  Does the status show the number of
satellites in view and are most of them 'tracked'?

> Oncore GT+: does it need a pulse stretcher?
None of mine ever needed any pulse stretching.

Another item to note, when NTP initializes your Oncore, does the PPS LED
stop blinking?  Mine stops until the other peers get synced and then the
Oncore driver sends the receiver command to start polling sequence for
the time.  I guess this is to allow the receiver to initialize, check
the almanac for validity and then put the receiver in the '0D' Mode.
About 10 minutes after restarting NTP, my PPS LED starts blinking again.
I see that you have a 'real' serial port, this is good.

There is a wealth of information on the TAPR website including the
Motorola manuals that give meaning to all of those @@x commands.  Having
those manuals and using WinOncore has allowed me to get all of my
problems resolved.


Public Keys:
PGP KeyID = 0x5F22FDC1
GnuPG KeyID = 0x620836CF

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