If one has a digitized sample (of TBD length) of a "good" sine wave, has someone got a cookbook way to get the phase noise and/or Allan deviation of the sampling process (mostly dominated by the sample clock oscillator, but potentially other noise sources)? I can do something like break the samples into shorter chunks, fit a sine wave to the sampled data. Use the frequency (or phase) of those measurements as input to a AVAR calculation, for instance. Typical samples would be at 2.048 MHz for 2-10 seconds (so not particularly useful for AVAR, to be fair) Jim

Hi Jim, On 2025-07-16 00:37, Jim Lux via time-nuts wrote: > > > > If one has a digitized sample (of TBD length) of a "good" sine wave, has someone got a cookbook way to get the phase noise and/or Allan deviation of the sampling process (mostly dominated by the sample clock oscillator, but potentially other noise sources)? > > I can do something like break the samples into shorter chunks, fit a sine wave to the sampled data. Use the frequency (or phase) of those measurements as input to a AVAR calculation, for instance. > > Typical samples would be at 2.048 MHz for 2-10 seconds (so not particularly useful for AVAR, to be fair) So, the modern way to do this is to use CORDIC, track the phase output for PM, subtract a reference phase-ramp, decimate data step-wise with good filters to fit your needs, then FFT to your hearts delight for PM spectrum. See IEEE Std 1139 for instance. Cheers, Magnus