信号的谱分析就是计算信号的频谱（信号的傅氏变换），通过信号研究分析信号特性。信号频谱是连续的，不能用数字信号处理方法计算，按频域采用定理， 序列的DFT完整反映了频谱信息，所以可以通过DFT进行谱分析。

用 FFT 对连续信号和时域离散信号进行谱分析.-Spectral analysis of the signal is to calculate the signal spectrum (Fourier transform of the signal), through the signal analysis of signal characteristics. Signal spectrum is continuous, can not be used to calculate the digital signal processing method, according to the frequency domain using the theorem, the sequence of DFT fully reflects the spectral information, so you can spectrum analysis by DFT.

The FFT and the time domain discrete signal are analyzed by FFT.