1. Fourier transform. FFT. FFT

Preliminaries. Notations

A Fourier transform-based signal analyzer provides time and frequency, or even time-frequency, information on the signal applied to it, by digitally processing the signal . If the signal analyzer only provides spectral characteristics, it is often referred to as a spectrum analyzer.

Although digital processing itself can be envisaged without explicit recourse to the notions of time and frequency, these notions remain indispensable if we wish to relate the calculated spectral values to the physical frequency content of the a priori...