最近看到有人提问怎样用FFT实现频谱分析，我认为能够进行到频谱分析的人，对于系统研究的深度基本上已经相当不错了。本人今天做了一个例程，发给大家参考一下。

历程主要内容(signal_analyzer.rar)如下：

test1.txt 第一列为时间t，0.001s为步长；第二列为系统的输入信号；第三列为系统的输出信号。

signal_analyzer.m首先将test1.txt 的数据读入workspace，然后进行FFT，分析出两信号的频率，输出对于输入的幅值衰减（db），输出对输入的相位差。-The question was asked recently to see the realization of how to use FFT spectral analysis, I think that spectral analysis can be carried out to those who study the depth of the system basically is already quite good. Today I made a routine, distributed to Members for reference. The main contents of the course (signal_analyzer.rar) are as follows: test1.txt the first time as t, 0.001s for the step　the second as the system input signal　the third as a system output signal. signal_analyzer.m first test1.txt data read into workspace, and then proceed to FFT, analysis of the two signal frequency, output amplitude for input attenuation (db), the output of the input phase difference.