%生成凱撒窗
beta=4;
w1=kaiser(20,beta);
w2=kaiser(60,beta);
w3=kaiser(90,beta);
[W1,f]=freqz(w1/sum(w1),1,512,2);
[W2,f]=freqz(w2/sum(w2),1,512,2);
[W3,f]=freqz(w3/sum(w3),1,512,2);
plot(f,20*log10(abs(W1)),'r:',f,20*log10(abs(W2)),'g-',f,20*log10(abs(W3)),'b*');
legend('n=20','n=60','n=90');