[time-nuts] looking for low-power system for gps ntp timekeeping NANOSG20

[folkert]

> Thanks for your graphs, but what are the Y-axis units!

http://keetweej.vanheusden.com/~folkert/nanosg20.png is in ms and not
the delay, the offset instead.

> 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.

well the offset is not constant. Now it is even 1 second:

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
x127.127.28.0    .NMEA.           0 l    5   16  377    0.000  -1002.1   0.096
*127.127.28.1    .PPS.            0 l    9   16  377    0.000  -1000.2 394.379
+192.168.64.18   .PPS.            1 u   64   64  377    0.548   -0.360   3.083
+192.168.64.2    .PPS.            1 u  108  128  377    0.251   -1.128   0.918
-192.168.64.168  .PPS.            1 u   34   64  377    1.153   -0.755   3.958

> Can you check that out?  I recall that

I can but I think (open for telling me I'm wrong) the primary problem is with the offset jumping all over the place: see my mail a couple of minutes ago.

> 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.

I'll have a look at it this weekend.


Folkert van Heusden

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