%N =51

%求矩形窗的频率响应图

wn = rectwin(51) ; %矩形窗函数

%20*log10(abs(WN))

[h1,w] = freqz(wn,1);

figure(1);

plot(w/pi,20*log10(abs(h1/max(h1))));

axis([0 1 -100 0]);

xlabel('归一化频率/\pi');

ylabel('20log_{10}|W(e^{j\omega})| /dB');

title('矩形窗的傅里叶变换');

set(gca,'YTick',[-100 -80 -60 -40 -20 0])

set(gca,'XTick',[0 :0.2: 1])

set(gca,'XAxisLocation','top'); %设置X轴在上方set(gca,'YAxisLocation','left'); %设置Y轴在左方text(1,-108,'\pi');%gtext('\pi');

%求三角窗的频率响应图

wn1 = bartlett(51);

[h1,w1] = freqz(wn1,1);

figure(2);

plot(w/pi,20*log10(abs(h1/max(h1))));

axis([0 1 -100 0]);