FREQUENCY ANALYSIS METHOD AND APPARATUS, AND SPECTRUM SPREAD DEMODULATION METHOD AND APPARATUS

摘要

A method for performing frequency analysis by executing discrete Fourier transform with a smaller capacity of a memory than in usual FFT processing, without reducing the frequency resolution. A-power-of-two NA = 2a (where "a" is an integer) memories for discrete Fourier transform are prepared. A former-stage calculation step of taking out frequency components of an input signal having a-power-of-two NB = 2b (where "b" is an integer and b > a) data items, in a comb manner and of calculating NA intermediate data items and a latter-stage calculation step of applying fast Fourier transform to the intermediate data items obtained in the former-stage calculation step, by using the NA memories for discrete Fourier transform are executed 2b-a times with the frequency components taken out in the comb manner being changed, to execute discrete Fourier transform through 2b-a operations.