[time-nuts] Calculate spectral content from a series of zero crossing time stamps?

[Magnus Danielson]

Hi Henk,

On 08/02/11 22:19, Henk wrote:
> Hi,
>
> Wavecrest uses algorithms for this and their software gives a spectrum. They also give some info on their site.

In "Jitter, Noise and Signal Integrity at High-Speed" by Mike Peng Li, 
Prentice Hall, ISBN 0-13-242961-6 it is covered in pages 200-207.

It converts the phase jitter Phi(t) into the autocorrelation function 
R_Phi(tau) (equation 7.40) and then the phase jitter PSD can be 
estimated using the fourier transform (equation 7.41). The phase-noise 
can then be calculated using the standard L(f) = 10*log10(PSD(f)/2). 
It's pretty straight-forward.

The autocorrelation processing is O(N^2) while the DFT can be done in 
O(N log N) when using FFT. As usual these can be implemented in reversed 
order such that first the FFT is done to the phase jitter and 
auto-correlation can be found using O(N) post-processing.

The phase-noise measuring ability of the SIA-3000 I have is not 
competing with real phase-noise measuring sets. It doesn't say it can't 
be useful.

Cheers,
Magnus