Hi,
I decided to buy a Nanos G20. Not too expensive, real serial port,
debian linux pre-installed.
I don't want to sound harsh as the people from Nanos probably did their
best to produce a good product, but for timekeeping it is totally crap
and also useless.
Well, unless I did something wrong.
I recompiled the kernel to enable PPS support, installed gpsd and ntpd,
configured at all and let it run for a while.
allan deviation:
http://keetweej.vanheusden.com/~folkert/nanosg20/allandev.png
offset: http://keetweej.vanheusden.com/~folkert/nanosg20.png
remote refid st t when poll reach delay offset
jitter
==============================================================================
x127.127.28.0 .NMEA. 0 l 3 16 377 0.000 -994.05
7.857
x127.127.28.1 .PPS. 0 l 7 16 377 0.000 -250.13
572.812
+192.168.64.18 .PPS. 1 u 66 128 377 0.553 -0.055
0.033
*192.168.64.2 .PPS. 1 u 99 128 377 0.237 -0.062
0.039
+192.168.64.168 .PPS. 1 u 44 128 377 0.646 -0.013
0.321
Folkert van Heusden
======================================
Folkert,
Thanks for your graphs, but what are the Y-axis units!
Inn your billboard above, the PPS looks to be on the wrong edge - perhaps
the pulse is 250 ms wide and you are syncing to the trailing edge and not
the leading. Can you check that out? I recall that it's the positive going
transition on the DCD connection which needs to be on the exact second. I
think you are using the Garmin GPS 18x LVC. There was a firmware update
which ensured that the serial adta arrived /before/ the /next/ second edge
rather than after it. Ensure your firmware is 3.70 or later. See:
http://www.satsignal.eu/ntp/Garmin-GSP18x-LVC-firmware-issue.htm
I see that 3.80 is now out, but I think I am still on 3.70.
Hope that helps....
Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: [email protected]
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