[time-nuts] Re: Phase noise with a lock-in amplifier.

John Miles jmiles at pop.net
Mon Apr 18 09:38:52 EDT 2005

> Surely, if you had an A/D of infinite resolution, with zero jitter, you
> could work out the phase noise of any oscillator from those samples? An
> FFT would give you the phase noise directly.
> I appreciate that to get a A/D with zero jitter you would need an
> oscillator with zero jitter, so one has not avoided the need for a low
> noise oscillator.

Hmm.  That's actually a good point; I wasn't thinking about the ADC clock
being equivalent to the "clean" oscillator reference, but it is.  Naturally,
you can separate the noise and signal to any desired degree of resolution
with an FFT, given enough sampling points.

-- john KE5FX

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