[time-nuts] GPSDO simulation tool

Magnus Danielson magnus at rubidium.dyndns.org
Sat Mar 22 17:13:08 EDT 2014

Hi Tom,

On 22/03/14 21:00, Tom Van Baak wrote:
> Hi Chris,
> I'm pretty sure John distributes complete source code to TimeLab as part of the installation.
> My source code is at www.leapsecond.com/tools
> There are also many open source plotting tools available.
> Not sure what you're complaining about, really.

Agree. Download and see what you get. I have not been upset so far, and 
I sing the praise of open software on a regular basis. So just look.

> Please try using the GPSDO simulator and let's talk time & frequency instead of open & closed operating systems.

On that note.

Had to this code after the includes to compile in a Debian box, and yes, 
I needed -lm flag naturally since pow needs it.

double min(double a, double b)
	if (a > b)
		return b;
	return a;

That's as far as I get:
./gpsim1 gps.dat osc.dat > gpsdo.dat
** GPS 400000 samples in file gps.dat
./gpsim1: open failed: osc.dat

Verified files, they are OK. Will have to take a look at the code 
details, but nothing obvious.

> Here's an example of what you can do -- varying the pre-filter from 1 to 1000 seconds.
> First, using the cute little Adafruit "Ultimate GPS" MTK3339 board: gpsim-22.gif
> Second, using the fancy CNS-II M12+T box: gpsim-23.gif
> Both with the same OCXO and same gpsim1 default P,I,D parameters.
> These plots would have taken weeks of data collection. Instead it took 20 seconds with the simulator.

I like the approach of doing a simulator. I have not had the time to try 
it until today.

I think you should do a gpsim1.txt to describe the usage and options.


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