[time-nuts] GPSDO simulation tool

Chris Albertson albertson.chris at gmail.com
Sat Mar 22 14:56:49 EDT 2014

Yes I could run most any MS Windows software on my iMac.   But running
it is not the point.  Closed source software like this is just a
"magic black box" and you can't see how it works.

The point is like this:  Why build a GPSDO when you can simply buy a
Thunderbolt, apply power and go?    The same answers apply to
software. You want to learn the issues involved, you want to modify it
or use it in a different environment.

Especially the last part, different environment.  I'd like to have my
GPSDO draw performance plots and some diagnostics on a little cell
phone size LCD screen.

On Sat, Mar 22, 2014 at 5:17 AM, Tom Van Baak <tvb at leapsecond.com> wrote:
>> What's the best way to make an ADEV plot, other then using time lab?
>> Timelab appears to be an MS Windows .exe file.    I could write a
>> script based on the definition of adev but I bet someone has already
>> done this.
> Chris,
> John's TimeLab gives you much more than ADEV; the ability to display multiple data files and to pan/zoom/average the phase and frequency plots is really nice, especially for GPS 1PPS data. Surely someone on the list has a way to run his Windows program on a different OS. Still, if you don't want to use Stable32 or Plotter or TimeLab, that's no problem. I prefer scripts over GUI myself.
> If it's just ADEV you want, use adev5.c (under www.leapsecond.com/tools/). You can run a GPSDO simulation and pipe the output to adev5 directly:
>     gpsim1 gps-m12cns2.txt ocxo.dat | adev5 /a 0 5
> For more sigma,tau points, try:
>     gpsim1 gps-m12cns2.txt ocxo.dat | adev5 /a 0 5 0.1
> Then use gnuplot or your favorite plot tool to make the log-log plot.
> As an example, attached are ADEV+MDEV examples for the M12+T and the mtk3339 GPS receivers, tau 10^0 to 10^5:
>     gpsim1 gps-m12cns2.txt ocxo.dat | adev5 /am 0 5 .1 | gplot2.sh
>     gpsim1 gps-mtk3339.txt ocxo.dat | adev5 /am 0 5 .1 | gplot2.sh
> /tvb
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Chris Albertson
Redondo Beach, California

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