[time-nuts] GPS lock of the FE5680. Current experiment and question

[David]

On Fri, 10 Feb 2012 17:28:53 -0800, Chris Albertson
<albertson.chris at gmail.com> wrote:

>On Fri, Feb 10, 2012 at 5:10 PM, David <davidwhess at gmail.com> wrote:
>
>> All you need for this is the flip-flop.  Clock the flip-flop with the
>> 1 PPS signal and capture whether the oscillator is leading or lagging.
>
>I can see how this can detect lock.  If the FF is the same each second
>you are good.  But if it changes how do you know the direction of the
>change?

It only detects if the phase difference is leading or lagging.
Assuming that the frequency is locked, the FF should return a 50/50
distribution when phased locked.