hamming.m

四种窗函数设计FIR数字滤波器matlab源码（hant,hamming,blackman,kaiser)

format short e;
wp=2*pi*3000;
wa=2*pi*5000;
ws=2*pi*20000;
alpha=0.54;
Bt=wa-wp;
wc=0.5*(wa+wp);
Nmin=ceil((4*ws)/Bt);
disp('Nmin='),disp(Nmin);
N=input('N=');
n=[0:1:N-1];
m=n+eps;
T=2*pi/ws;
hd=sin(wc*m*T)./(pi*m);
n=[0:1:(N-1)/2];
m=n+eps;
wn=alpha+(1-alpha)*cos((2*pi*m)./(N-1));
Wn=[wn zeros(1,N-length(wn))];
hn=hd.*Wn;
L=length(wn);
hn_r=zeros(1,L);
for l=1:1:L;
    hn_r(l)=hn(1,l);
end
hn_fliplr=fliplr(hn_r);
if floor(N/2)==(N-1)/2; %N is odd;
    hn_l=zeros(1,L-1);
    for k=1:1:L-1;
        hn_l(k)=hn_fliplr(1,k);
        hn=[hn_l hn_r];
    end
else hn=[hn_fliplr, hn_r];
end
n=[-(N-1)/2:1:(N-1)/2];
m=n+eps;
wn=alpha+(1-alpha)*cos((2*pi*m)./(N-1));
n=0:1:(N-1);
subplot(2,1,1),stem(n,wn);
xlabel('n');ylabel('W_H(n)');
grid on;
subplot(2,1,2),stem(n,hn);
xlabel('n'); ylabel('h(n)');
grid on