FIR滤波器窗函数及其MATLAB例程.doc

矩形窗：的归一化幅度谱

汉明窗的归一化幅度谱

汉宁窗的归一化幅度谱

凯撒窗的归一化幅度谱

程序如下：
clear all
close all
eps=0.0001;
N=32;
win_rect(1:N)=1
win_ham=hamming(N)
win_han=hanning(N);
win_kaiser=kaiser(N,pi);
win_kaiser=kaiser(N,5);
win_kaiser=kaiser(N,pi);
win_kaiser2=kaiser(N,5);
Yrect=abs(fft(win_rect,512));
Yrectn=Yrect./max(Yrect);
Yrectn=Yrect./max(Yrect)
Yham=abs(fft(win_ham,512));
Yhamn=Yham./max(Yham);
Yhan=abs(fft(win_han,512));
Yhann=Yhan./max(Yhan);
YK=abs(fft(win_kasier,512));
YK=abs(fft(win_kaiser,512));
YKn=YK./max(YK);
YK2=abs(fft(win_kaiser2,512));
YKn2=YK2./max(YK2);
figure(1)
plot(20*log10(Yrectn+eps),'k')
xlabel('Sample number')
ylabel('20*log10(amplitude)')
axis tight
grid
figure(2)
plot(20*log10(Yhamn+eps),'k')
xlabel('Sample number')
ylabel('20*log10(amplitude)')
grid
axis tight
figure(3)
plot(20*log10(Yhann+eps),'k')
xlabel('Sample number')
ylabel('20*log10(amplitude)')
grid
axis tight
figure(4)
plot(20*log10(YKn+eps),'k')
grid
hold on
plot(20*log10(YKn2+eps),'k--')
xlabel('Sample number')
ylabel('20*log10(amplitude)')
legend('Kaiser par.=\pi','kaiser par.=5')
axis tight
hold off