FFT Analyzer Basic FAQ

A Fourier spectrum is the result of a Fourier transform on a time signal, expressed as a function of frequency, and is usually a function of complex numbers. However, in FFT analyzers, the complex Fourier series obtained by expanding a finite time window as the fundamental period is called the Fourier spectrum. Therefore, if the physical unit of the time signal is EU (V), the unit of the absolute value of the Fourier spectrum is also expressed as EU (V).

input signalWhen this is expressed as a complex number, we get equation (1).

Here, Re represents the real part of a complex number.This is a vector rotating counterclockwise on the unit circle with angular velocity (angular frequency) ω (ω = 2π f,frequency f (The component) Therefore, frequency f The Fourier spectrum at is given by equation (1) t When set to = 0 Complex amplitude value () This is the result. Here, A and φ are the magnitude (mag) and phase (phase) of the Fourier spectrum, respectively.