%用窗函數(shù)設(shè)計(jì)FIR濾波器
passrad=100*2*pi/1000;
w1=boxcar(81);
w2=triang(81);
w3=hanning(81);
w4=hamming(81);
n=1:1:81;
hd=sin(passrad*(n-41))./(pi*(n-41));
hd(41)=passrad/pi;
h1=hd.*rot90(w1);
h2=hd.*rot90(w2);
h3=hd.*rot90(w3);
h4=hd.*rot90(w4);
[MAG1,RAD]=freqz(h1);
[MAG2,RAD]=freqz(h2);
[MAG3,RAD]=freqz(h3);
[MAG4,RAD]=freqz(h4);
subplot(2,2,1),plot(RAD,20*log10(abs(MAG1)));grid on;
subplot(2,2,2),plot(RAD,20*log10(abs(MAG2)));grid on;
subplot(2,2,3),plot(RAD,20*log10(abs(MAG3)));grid on;
subplot(2,2,4),plot(RAD,20*log10(abs(MAG4)));grid on;