[ntp:questions] fudge time1 for gps-18x-LVC?

David Lord snews at lordynet.org
Sat Feb 6 23:03:09 UTC 2010

David J Taylor wrote:
> "unruh" <unruh at wormhole.physics.ubc.ca> wrote in message 
> news:slrnhmrgjr.e6q.unruh at wormhole.physics.ubc.ca...
> []
>> He said that he had left the GPS18 in its default mode, where much more
>> than a single sentence is sent out ( about 4 of them if I remember
>> correctly). He shold probably set it so just the single required
>> sentence is sent out.
> Indeed, but I think we've talked about this before with David and 
> "default" may mean "default for use with NTP".  We'll see.  Certainly 
> the single sentence is the best - I happen to use: $GPRMC.

Thanks for that page with the scope traces. It suggests I'm in
right ballpark for fudge time and also confirms same signal
polarity for pps from my MSF receiver.

I had single RMC sentence configured way back when I last used
the 18x-LVC but RMC seemed way too short for a 350ms offset so
I guessed the 18x-LVC had lost its settings. I'll guess again
now that it hasn't. I'd switched it off early this morning and
forgot to check then. Now minicom shows it is still set for RMC.

When I brought the BR-304 out again in November after failing
to get any useful timekeeping from it in March/April, I found
that had reverted back from RMC to its default sentences, but
that is claimed to have a supercap rather than battery.

Next experiment is to try type 22 atom driver without type 20
nmea driver and have the three ntp servers for giving the
correct second. I'll try with parallel pps first since I was
unable to get this to work on desktop downstairs and it is
already wired up for that.



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