Hi all

The data can be a bit hard to read in an email. So I will give it another try.

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 used a terminal program to log the NMEA data to a file and do the PC 
timestamp. Calculations were done in a spreadsheet by me. The PC-time is kept 
under control by Meinberg and also OK vs. <http://www.time.is> during the time 
of observation.

The PC-timestamp wobble is not the issue. It is a combination of the PC-time 
itself and the NMEA wobble. Nobody should expect the NMEA data to come at the 
same time every time relative to the 1 PPS. As Björn correctly points out it is 
always late and wobbles with processor load.

Sometimes the 2-something lag can last for many hours - I have seen more than 
48 h.

The issue is the "seconds jump". The issue is not the relative difference 
between the PC-time and the GPS-time but the jump, e.g. using Tac32 reveals 
that the TU30 is always ~1200 ms late on in case of the "jump second" ~2300 ms 
late.

I wonder if it has anything to do with the Week 1024 Syndrome?

Indeed the TU30 is a old device. I guess some 30 years if not more looking at 
the components. F/W I have no idea.

The 10 kHz seems unaffected.

Bo

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