The Fourier transform is the basic principle of frequency analysis. It assumes that each harmonic oscillation can be broken down into any number of sinusoidal and cosinusoidal waves, the sum of which reproduces the original oscillation. Linked individual waves are "broken down" again accordingly.
Probably the most well-known concept in connection with signal processing and frequency analysis is the fast Fourier transform, or FFT.
In order to be able to evaluate single partial oscillations into amplitude and frequency, the digitized time signal is converted into a frequency spectrum. In addition, a small extract is taken from the signal; this is known as the time window. Using the FFT algorithm, the frequency spectrum is calculated from this so that each involved oscillation and its associated frequencies and amplitudes is shown as a single line in the line spectrum.
傅里叶变换是频率分析的基本原理。它假定每个谐波振荡可以被分解成任意数量的正弦波和余弦波，其总和再现了原始振荡。与之相关的各个波又被相应地 "分解 "了。
与信号处理和频率分析有关的最著名的概念可能是快速傅里叶变换，或FFT。
为了能够评估单个部分振荡的振幅和频率，将数字化的时域信号被转换为频域。此外，从信号中提取一小部分；这被称为时间窗口。使用FFT算法，从中计算出频谱，从而将每个涉及的振荡及其相关的频率和振幅显示为线谱中的单条线。
For a single sine signal with a constant frequency, a single line is shown in the frequency spectrum.
对于一个频率恒定的单一正弦信号，在频谱中显示为一条线。