[time-nuts] Measure GPSDO stability with minimum resources?

[Bob Stewart]

For my GPSDO, I need to calculate the OCXO aging for holdover projection purposes as well as get some figure of merit for the recent past of the OCXO stability.  The latter is so that I can determine that the PLL has (or soon will have) a good lock.  I'm developing on a dfPIC33FJ128MC802, and I've used about 70% of the code space,  I could probably set aside 4K bytes of data space for this calculation.  

I have a rather primitive way of doing part of this, but I was hoping someone would steer me to something a bit better.

Bob