https://github.com/folkertvanheusden/pps-comparer

Measures the difference between PPS pulses
https://github.com/folkertvanheusden/pps-comparer

pps time

Last synced: 8 days ago
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Measures the difference between PPS pulses

• Host: GitHub
• URL: https://github.com/folkertvanheusden/pps-comparer
• Owner: folkertvanheusden
• Created: 2024-07-23T20:06:32.000Z (almost 2 years ago)
• Default Branch: master
• Last Pushed: 2026-03-29T11:23:44.000Z (3 months ago)
• Last Synced: 2026-05-18T21:45:56.198Z (about 1 month ago)
• Topics: pps, time
• Language: C++
• Homepage:
• Size: 58.6 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
To be able to compile this, you need the pps-tools and cmake packages. libgps-dev is optional.

To run:

    sudo ./pps-comparer -1 /dev/pps0 -2 /dev/pps1 -l log.dat

Press ctrl+c to stop measuring

When you've got libgps-dev installed during build, -g  adds gpsd stats to the output.

If you have saved the output to e.g. test.dat (-l test.dat), you can plot the Allan deviation plot with:

    ./plot-allan.py test.dat test.svg

test.svg is then the output-graph.

For a histogram or as a time-series, use plot-hist.py and plot-ts.py.

Note: when pulses are missing(! e.g. when GPS loses fix), the comparison goes haywire.

Output (with GPS - which is optional):

```

nr    ts1                  ts2                  difference   missing1/2 difference-drift fix hdop

10852 1732126554.000050923 1732126554.000046496 4.427000e-06 548/88     2.783154e-10     3   1.760000

10853 1732126555.000050482 1732126555.000044753 5.729000e-06 548/88     2.206966e-10     3   1.760000

10854 1732126556.000049989 1732126556.000045875 4.114000e-06 548/88     3.406431e-10     3   1.760000

...

```

Two bad time-sources:

![allan deviation](images/AD.svg)

Released under the MIT license by Folkert van Heusden.