IIR低通滤波的结果分析-往事只能回首的回答

IIR低通滤波的结果分析

2019-07-17 14:46发布

ti, simsun, sans-serif">明明的低通为啥滤波后是空白？高通的也是空白。求解释。详细点~clear;close all
[z,fs,bits]=wavread('e:1234.wav')
y=z(1:8192)
Y=fft(y)
fp=1000;fc=1200;As=100;Ap=1;Fs=8000
wc=2*fc/Fs;wp=2*fp/Fs
[N,ws]=buttord(wc,wp,Ap,As)
[b,a]=butter(N,ws)
figure(1)
freqz(b,a,512,Fs)
x=filter(b,a,z)
X=fft(x,8192)
figure(2)
subplot(2,2,1);plot(abs(Y));axis([0,1000,0,1.0])
title('滤波前信号频谱')
subplot(2,2,2);plot(abs(X));axis([0,1000,0,1.0])
title('滤波后信号频谱')
subplot(2,2,3);plot(z)
title('滤波前信号波形')
subplot(2,2,4);plot(x)
title('滤波后信号波形')