dhpf.m

Matlab环境下带控制面板的低通、高通滤波器设计

N0=str2num(get(findobj(gcf,'tag','N'),'string'));
wr=str2num(get(findobj(gcf,'tag','wr'),'string'))*pi;
wp=str2num(get(findobj(gcf,'tag','wp'),'string'))*pi;
Ap=str2num(get(findobj(gcf,'tag','Ap'),'string'));
Ar=str2num(get(findobj(gcf,'tag','Ar'),'string'));
[N,wn]=buttord(wp/pi,wr/pi,Ap,Ar);
if N0>N
    N=N0;
end
if wp<=wr
    error('通带边缘必须大于阻带边缘');
end
fprintf('\n***巴特沃斯模拟滤波器阶次=%2.0f\n',N);
[b,a]=butter(N,wn,'high');
[C,B,A]=dir2cas(b,a);
[db,mag,pha,w]=freqz_m(b,a);
subplot(2,2,1);plot(w/pi,mag);AXIS([-0.1 1.1 0 1]);title('幅度响应Ha(j\Omega)');
subplot(2,2,2);plot(w/pi,db);AXIS([-0.1 1.1 -50 1]);title('幅度响应(dB)');
yn=casfiltr(b0,B,A,xn);