Can phase noise be averaged out?
Let us model additive noise, atop a sinusoidal carrier, as 2 small noise sources in quadrature.
We have this vector diagram



simulate this circuit &ndash; Schematic created using CircuitLab
The inphase noise is AM: amplitude modulation noise.
The quadrature noise is PM: phase modulation, or phase noise or jitter.
Is there any specific reason why more samples, averaged together, would not produce a lower standard deviation?
By the way, what is the ADC/sampling_clock phase noise spectrum?
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Oct 31, 2020
Ahem. Phase is indeed additive.
Take a clean (clean enough) sinsoid, and sum with random noise.
The Time Jitter (phase noise, by another computation) is
Tj = Vnoise / SlewRate
and you can convert from Time Jitter to Phase noise, by recognizing the
PERIOD OF THE CARRIER versus the 1-sigma (RMS) of the computed Tj.