exe0604_a.m

来自「Matlab程序为清华大学胡广书版信号处理的上机习题答案」· M 代码 · 共 39 行

%-------------------------------------------------------
% exa0604.m
% to design a Chebyshev-I DF.
%-------------------------------------------------------
clear all;

f1=44;f3=56;
fsl=47;fsh=53;
rp=3;rs=50;
Fs=1000;
%
wp1=2*pi*f1/Fs;
wp3=2*pi*f3/Fs;
wsl=2*pi*fsl/Fs;
wsh=2*pi*fsh/Fs;
wp=[wp1 wp3];ws=[wsl wsh];
%
% Firstly to finish frequency prewarping;
wap=2*Fs*tan(wp./2);
was=2*Fs*tan(ws./2);
[n,wn]=cheb1ord(wap,was,rp,rs,'s');
[z,p,k]=cheb1ap(n,rp);
[bp,ap]=zp2tf(z,p,k);
bw=wap(2)-wap(1);
w0=sqrt(wap(1)*wap(2));
[bs,as]=lp2bs(bp,ap,w0,bw);
% Note: z=(2/Ts)(z-1)/(z+1);
[bz1,az1]=bilinear(bs,as,Fs)
[h,w]=freqz(bz1,az1,256,Fs);
plot(w,20*log10(abs(h)));grid on;

hp=unwrap(angle(h));
figure;
plot(w,hp);grid on;
ylabel('Phase of TranFunction')