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Entry  Mon Dec 5 10:39:16 2016, Gabriele, Electronics, Configuration, Trying to debug GPS time issue 
    Reply  Tue Dec 6 09:02:17 2016, Gabriele, Electronics, Configuration, Trying to debug GPS time issue 
       Reply  Tue Dec 6 10:38:19 2016, Gabriele, Electronics, Configuration, Trying to debug GPS time issue Screenshot.pnggps_time_offset.png
          Reply  Tue Dec 6 11:22:58 2016, Gabriele, Electronics, Configuration, Trying to debug GPS time issue Screenshot-3.png
             Reply  Tue Dec 6 16:55:51 2016, Gabriele, Electronics, Configuration, Trying to debug GPS time issue Screenshot.png
                Reply  Wed Dec 7 08:14:05 2016, Gabriele, Electronics, Configuration, Trying to debug GPS time issue Screenshot-1.png
                   Reply  Wed Dec 7 16:27:11 2016, Gabriele, Electronics, Configuration, Trying to debug GPS time issue 
                      Reply  Thu Dec 8 09:26:10 2016, Gabriele, Electronics, Configuration, Trying to debug GPS time issue figure_1.pngfigure_1.png
Message ID: 227     Entry time: Tue Dec 6 09:02:17 2016     In reply to: 224     Reply to this: 228
Author: Gabriele 
Type: Electronics 
Category: Configuration 
Subject: Trying to debug GPS time issue 

Things seems to be worse now. This morning I injected noise at GPS 1165078533 (real time, as obtained from the python command line, and consistent with what displayed in the MEDM screen) and found the injection in the data at GPS 1165078555, so 22 seconds later...

Quote:

For a long time I had problems with the GPS time in frames being different from the real one.

This morning I rebooted the cymac3 and swapped the function generator with a new one.

I tested the GPS time in frames by switching on teh ESD noise at a given GPS time and checking the frames. The times are aligned.

I'll have to wait and see if this remains stable over time (in the past i saw an acculation of few seconds per day)

 

EDIT: I checked the two SR DS345 one against the other. Indeed, when bpth set to generate 65536 Hz, there is a continuos drift in the relative phase, accounting for one cycle over about 3.9 seconds. This would sum up to one second over ~256000 seconds, or about 3.5 days. It seems more or less comparable with the amount of GPS time mis-syncronization I saw. I'll have to wait a few days to see if the new clock is stable.

 

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