[time-nuts] 4046 experiment for gpsdo
Bob Camp
kb8tq at n1k.org
Sun Sep 27 00:04:14 UTC 2015
Hi
If you digitize the beat note it’s fairly simple:
The beat note is not really a sine wave. It’s periodic, but not a pure sine. The
reason is fairly simple. The frequency changes as the beat note changes the EFC.
You have a lower frequency as it gets closer to the “zero frequency”.
The net result is a signal that is a bit flat on the side that is towards the zero. It’s a
bit sharper away from the zero. Fit it with a sine wave and you will get a residual. From that
you can work out which side is which.
Bob
> On Sep 26, 2015, at 5:47 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
>
>
> magnus at rubidium.dyndns.org said:
>> Another method would be to measure the phase-detector beat-note frequency
>> (most have mixer-like behavior), which you should be able to measure with
>> quite good precision, then set the EFC accordingly and then close the loop.
>
> How do you get the sign out of a beat note?
>
>
> --
> These are my opinions. I hate spam.
>
>
>
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