[time-nuts] TU30 jump second

"Björn Gabrielsson" bg at lysator.liu.se
Tue Apr 4 08:14:48 EDT 2017


Hi Bo,

Are you getting data in binary format [1] or NMEA? The NMEA mode for some
Jupiter receivers are known to behave badly in NMEA-mode. The delay would
go from 1:ish to 2:ish seconds depending on signal processing load.

--

     Björn

[1] Navman/Jupiter/Conexant/Zodiac/Rockwell binary... 
http://aprs.gids.nl/gpskit/documents/rockwell/iospec_w708.pdf


> Hi List
>
> Like many of you I also use a Navman Jupiter TU30 in a GPSDO. Besides the
> 10 kHz used for the PLL I also have a display showing time. But since a
> couple of years, Jan 15?, the time sometimes jumps -1 s and and then later
> returns by jumping +1 s Please see an example of the latter below:
>
> PC-time Diff. GPS-time Diff
> ...
> 011606.005 0.992 011604 1
> 011607.013 1.008 011605 1
> 011608.005 0.992 011607 2 <--- The issue
> 011609.013 1.008 011608 1
> 011610.004 0.991 011609 1
> ...
>
> I don't experience the same with a ublox GPS. I don't think I saw this
> more than two years ago and wonder if the GPS satellites send some
> correction data that the rather old TU30 misinterpret?
>
> Any clues?
>
> Thanks in advance
> Bo
>
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