基于MATLAB的FIR低通滤波器

function a=fir(x,N,wc); n=0:N-1; r=(N-1)/2; hdn=sin(wc*(n-r))/pi./(n-r);%计算单位脉冲响应 if rem(N,2)~=0 hdn(r+1)=wc/pi; end wn1=boxcar(N);%矩形窗 hn1=hdn.*wn1';%加窗 Hn=newfft(hn1,N); subplot(2,3,1); plot(abs(Hn)); grid; title('脉冲响应'); X=newfft(x,N); subplot(2,3,2); plot(abs(X)); grid; title('测试信号'); for i=1:N Y(i)=Hn(i)*X(i); %Z(i)=Y(1)^(-1); end %y=(1/N)*newfft(Z,N); subplot(2,3,3); plot(abs(Y)); grid; title('矩形窗滤波后'); wn2=hamming(N);%hamming窗 hn2=hdn.*wn2';%加窗 Hnn=newfft(hn2,N); subplot(2,3,4); plot(abs(Hnn)); grid; title('脉冲响应'); for i=1:N Yn(i)=Hnn(i)*X(i); %Z1(i)=Y1(1)^(-1); end %y1=(1/N)*newfft(Z1,N); subplot(2,3,6); plot(abs(Yn)); grid; title('hamming窗滤波后');