这个程序可以产生一个6阶的低通巴特沃思滤波器，截止频率是45Hz，你也可以用它来对信号进行滤波，并比较滤波前后的信号功率谱。-This program can generate a six-order low-pass Butterworth filter, cut-off frequency is 45Hz, you can also use it to filter the signal and to compare before and after filtering the signal power spectrum.