cnas.rar_离散信号变换

%---------------------------------------------------------------------------- % exa030201, for example 3.2.1 and fig 3.2.3; % to show Gibbs phenomena; %---------------------------------------------------------------------------- clear; wc=0.6*pi;a=[1];Nf=256; Hd1=ones(1,0.6*Nf+1); Hd2=zeros(1,0.4*Nf); Hd=[Hd1,Hd2]'; % 改变窗函数的长度，观察Gibbs现象 % M=10; % for M=10 N=2*M+1; for n=1:N if (n-M)==0; h(n)=wc/pi; else h(n)=sin(wc*(n-M))/(pi*(n-M)); end end [H,w]=freqz(h,a,Nf,1); subplot(221) plot(w,Hd,'-',w,abs(H));grid on; % M=30; % for M=30 N=2*M+1; for n=1:N if (n-M)==0; h(n)=wc/pi; else h(n)=sin(wc*(n-M))/(pi*(n-M)); end end [H,w]=freqz(h,a,Nf,1); subplot(222) plot(w,Hd,'-',w,abs(H));grid on; % M=50; %for M=50 N=2*M+1; for n=1:N if (n-M)==0; h(n)=wc/pi; else h(n)=sin(wc*(n-M))/(pi*(n-M)); end end [H,w]=freqz(h,a,Nf,1); subplot(223) plot(w,Hd,'-',w,abs(H));grid on; % M=100; % for M=100 N=2*M+1; for n=1:N if (n-M)==0; h(n)=wc/pi; else h(n)=sin(wc*(n-M))/(pi*(n-M)); end end [H,w]=freqz(h,a,Nf,1); subplot(224) plot(w,Hd,'-',w,abs(H));grid on;