exe060301_1.m

Matlab程序为清华大学胡广书版信号处理的上机习题答案

%----------------------------------------------------
% exe060301.m
% to design Butterworth high-pass DF with s=2/Ts*(z-1)/(z+1)
%----------------------------------------------------
clear all;

fp=400;fs=300;Fs=1000;
rp=3;rs=35;
% 
wp=2*pi*fp/Fs;
ws=2*pi*fs/Fs;
% Firstly to finish frequency prewarping ;
wap=2*Fs*tan(wp/2);was=2*Fs*tan(ws/2);
[n,wn]=buttord(wap,was,rp,rs,'s')
[z,p,k]=buttap(n);    %
[bp,ap]=zp2tf(z,p,k); %
[bs,as]=lp2hp(bp,ap,wap);   %

[bz,az]=bilinear(bs,as,Fs) %
[h,w]=freqz(bz,az,256,Fs);  %

figure;
plot(w,20*log10(abs(h)));grid on;
ylabel(' High-pass DF')

hp=unwrap(angle(h));
figure;
subplot(221);
plot(w,hp);grid on;
ylabel('我')