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

jimlux jimlux at earthlink.net
Thu Feb 10 05:13:38 UTC 2011


On 2/9/11 2:08 PM, Tijd Dingen wrote:
>
>
>> 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.
>
> If it can be done in N log N that would be nice. :)

autocorrelation:
FFT of input sequence, multiply each bin by itself, inverse FFT

So N(2logN+1) operations




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