ks04.m

《数字信号处理实验(MATLAB版)》这

nx=-2:10*pi;
x=square(nx/5);       %产生输入信号序列  

X=fft(x,N);
subplot(3,2,1);plot(nx,x);grid
ylabel('x(n)');title('y(n)=x(n)*h(n)');
subplot(3,2,2);stem(nx,abs(X));grid

a=[1,-0.34319,0.60439,-0.20407];
b=[0.1321, 0.3963,0.3963,0.1321];
nh=0:9;
hn=impz(b,a,nh);                       %求系统的单位冲激响应
H=ifft(hn,N);
subplot(3,2,3);stem(nh,hn);grid
ylabel('h(n)');
subplot(3,2,4);plot(n,H);grid
[y,ny]=convnew(x,nx,hn,nh);                         %卷积运算
Y=ifft(y,N);
subplot(3,2,5);plot(y);grid
ylabel('y(n)');
axis([0,N,1.1*min(y),1.1*max(y)]);
subplot(3,2,6);stem(abs(Y));grid