有了傅立叶变换，我们可以从信号的频域特征去分析信号。尤其在无线通信系统 中，傅里叶变换的重要性就更加明显了，无论是设计者还是测试工程师，在工作中都会和傅立叶变换打交道。-With the Fourier transform, we can go to analyze signals　the frequency domain characteristics of the signal. Especially in a wireless communication system, the importance of the Fourier transform becomes more apparent, whether designers or test engineers are at work and dealing with the Fourier transform.