Fast harmonic computation for digital relaying

It has been recently shown that the fast Fourier transform of a sequence wh ich slides over a time-limited rectangular window can be carried out in a n on-recursive manner by means of O (N) computations. The same idea is applie d in this paper to the digital relaying field, where only certain isolated harmonics, rather than the full spectrum, are needed, leading to O(log(2) N ) computations per harmonic. The particular case N = 16 has been used for c omparison purposes, showing that the new technique is less expensive than o ther non-recursive algorithms appeared in the literature.