PROCEDE DE DETECTION DE PRESENCE D'UN FREQUENCE PURE OU D'UNE FREQUENCE MODULEE LINEAIREMENT

摘要

Has stages which carry out the discrete Fourier transform over several successive sampling blocks and accumulate the results relative to amplitude for the selected part. The data taken into account for comparison is the accumulation variation. The Fourier transform is realized by timing of the quarter periods of samples submitted to the transform and summation of the timed samples. Includes a pseudo-module calculation stage for amplitude by summing absolute values of real and imaginary parts of a result from the Fourier transform. The sampling frequency is equal to a multiple divisible by eight for the frequency to analyze and the sampled signal is rectified before realizing the discrete Fourier transform. Method for detecting the presence of a frequency (Fp) in an analyzed signal. Includes the following stages: (a) Sample the analyzed signal using a sampling signal having a frequency (Fe) equal to a multiple (Ne) divisible by a quarter of the frequency to be detected; realize a discrete Fourier transform on at least a block of four samples corresponding to a period for a signal derived from the analyzed signal; determine from the Fourier transform at least data relative to amplitude for at least a selected part of the sampled signal and compare the data with data corresponding to the frequency to be detected.