27t.m

来自「包含50个数字信号处理方面的matlab程序」· M 代码 · 共 21 行

Rp=1.5;
Rs=20;
T=0.001;
wp=0.4*pi;
ws=0.6*pi;
wp1=(2/T)*tan(wp/2);
ws1=(2/T)*tan(ws/2);
[n,wn]=buttord(wp1,ws1,Rp,Rs,'s')
[b,a]=butter(n,wn,'s')
[bz,az]=bilinear(b,a,1/T);
[b0,B,A]=dir2par(bz,az)
[db,mag,pha,grd,w]=freqz_m(bz,az);
subplot(2,1,1);
plot(w/pi,db);
axis([0,1,-200,5]);
grid
subplot(2,1,2);
plot(w/pi,pha/pi);
axis([0,1,-1.2,1.2]);
grid