On Wed, Oct 5, 2016 at 6:46 PM, Bob Stewart <[email protected]> wrote: > What I'm really looking for is a way to do everything in the PIC. I've > been experimenting with saving the DAC value in a circular queue every 20 > seconds for 60 minutes, and plotting the difference value between the head > and tail of the queue every second. After posting this question, I took > another look at the overall behavior and decided to cut the queue size down > from 60 minutes to 5.
Hi Bob, Unless the oscillator is still warming up, 5 minutes or even 60 is way too short a time to look at aging. For aging, you will want to look at the change in DAC values over several days at least. Looking at the current value and one in the past will give you a feel for what is going on, but then you are discarding all the intermediate data. You really want to do a least squares fit using as many data points as you can handle, Check Wikipedia under Linear Least Squares for an example. What sort of phase detector are you using? If you want to see whether the system is locked, you may be better off looking at the phase detector signal.and declaring a lock if the low pass filtered phase error stays within a pre-determined range. -- --Jim Harman _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
