[ntp:questions] How to debug GPS PPS?

Thomas Laus lausts at acm.org
Sat Feb 13 14:58:27 UTC 2010


On 2010-02-12, xyz-2041 <xyz2041 at gmail.com> wrote:
> OK.  Couldn't get the Oncore unit to work in any way
> shape or form.  I bought a DB9 LED tester like this:
>
>  <http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260546635257>
>
> Had PPS going to pin 1, DATA OUT to pin 2, and DATA IN to pin 3.
> Still
> no good.
>
You didn't mention if your ground wire was connected to pin 5?  Did the
tester LED's flicker as expected?  Was there data passing in both
directions from and to the computer?  Was the PPS LED flashing one time
per second?

Your previous post to this group stated that your Oncore was working
with the Motorola WinOncore utility.  Did the observed satellites ever
show 'Locked' in the display?  The last time that I had to re-initialize
an Oncore, I found that the almanac file that shipped with WinOncore was
too old to be of any use with the current constellation.  My Oncores
seem to grab a new almanac quicker when placed in the NMEA mode.  I let
my receiver run until all satellites in view showed lock status and then
saved the almanac to a disk file.  I reinitialized my receiver in the
Motorola binary mode and loaded the new almanac that was just saved.
The receiver showed that it was locked within about 5 minutes.  Once it
was working correctly using the Motorola binary protocol, I connected it
to my FreeBSD time server and restarted NTPD.  Everything worked as
expected.

Tom


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