[time-nuts] Simple Octave GPSDO simulation with freq, phase and ADEV plots

[Erik Kaashoek]

For those that want to start with simulation, Octave is a good option. It's
fairly quick, powerfull, simple to learn and the plotting options are nice.
Attached a single short file with a simple GPSDO simulation including
simulated drift and a random PPS
The code for loading actual OXCO and PPS data is also present.
The simulation contains inactive code for an alpha-beta filter, similar to
a first order Kalman filter but with static parameters, but I could not get
this satisfactory working so it is disabled
The generated plot is also attached
To run, make sure Octave is installed, double click on the dosim.m file.
This should open the Octave GUI text editor with dosim.m loaded. Click on
the run button and wait some seconds. The plot window should appear.
The statement
graphics_toolkit("fltk")
may not be needed for your Octave installation and when commented out could
generate nicer plots.
I found the plots very helpful to understanding what a PPS disciplined
oscillator can, and can not do and the ADEV plot gives insight into
the quality of the tuning.
Erik.
[image: output.PNG]
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