%%%%%%%%%%%%%%%%%%%  fir濾波因子的設計  %%%%%%%%%%%%%%%
T=0.002;   % 采樣間隔
f0=60;     % 截止頻率
N=129;     % 采樣點為（2*N+1）
for k=1:N-1
    h(N-k)=sin(-k*2*pi*f0*T)/(-pi*k);
    h(N)=0;
    h(k+N)=sin(-k*2*pi*f0*T)/(pi*k);
end
for i = 1:N 
    h(i) = h(i) * (0.54 - 0.46 * cos(2 * pi * i / (N - 1)));   % 用漢明窗加權
end

% %%%%%%%%%%%%%%%% 對濾波因子加窗函數 %%%%%%%%%%%%%%%
% for k=1:2*N-1    
%     if k<=N-64||k>=N+64
%         h(k)=0;
%     end
% end
%%%%%%%%%%%%%%%%
H=abs(fft(h)).^2;
figure(1);
plot(h);