[time-nuts] GPS signal simulator

[Tom Van Baak]

>    In my quest to keep improving my GPSDO, a simple test tool 
> that I find indispensable is a GPS 1PPS (or 100Hz) signal simulator 
> reference.  Others may also find this useful because it allows testing the 
> PLL & DO in their GPSDO to Cs type accuracy using a standard OCXO.

Warren,

There's been some discussion about a GPS simulator for the
purpose of playing with GPSDO algorithms a couple of times
on the list over the years.

But since you're making more progress than most have, here
is a nice pair of 400,000 (!) sample data sets for you to use:

http://www.leapsecond.com/pages/gpsdo-sim/

For playing with GPSDO, the character of the typical 1PPS is
very easy to model (it's basically a few ns of noise that nicely
averages down at 1 over tau out past a day) so going all the way
back to RF simulation of the GPS SV signal(s) might be overkill.

In any event, I found it much easier to just take real GPS 1PPS
data, and real OCXO data, and then simulate a GPSDO from
those two raw data sets. You can plot phase, frequency, ADEV
of both inputs and one output and see the GPSDO humps we
always talk about, etc.

/tvb