fir.asv

FIR滤波器设计

wc=0.25*pi;N=33;
alpha=(N-1)/2;
n=0:1:N-1;
m=n-alpha+eps;
hd=sin(wc*m)./(pi*m);
wd2=hanning(N)';b2=hd.*wd2;
[H2,w]=freqz(b2,1);
subplot(2,2,1)
plot(w,abs(H2),'-.g')
legend('升余弦窗低通滤波器')
subplot(2,2,2)
plot(w/pi,20*log10(abs(H2)),':r')
legend('升余弦窗幅度响应（dB）')
subplot(2,2,3)
plot(n,b2,'--c')
legend('升余弦窗h(n)')
subplot(4,1,4)
plot(w/pi,alpha/pi,'--c')
legend('升余弦相位响应')