fft_hamm2.m

Matlab环境下带控制面板的低通、高通滤波器设计

N=1024;  %N-point DFT/FFT
L=161;   %length-L signal
n=0:L-1;
whm=0.54-0.46*cos(2*pi*n/(L-1));
y(1:L)=yn(21:(20+L)).*whm;
y((L+1):N)=0;  %Zero Padding
Yk=abs(fft(y));
YkM=max(Yk);
f=(0:(N/2-1))*fs/N;
Ykh=Yk(1:(N/2))/YkM;
subplot(2,2,1);
plot(f,20*log10(Ykh))
AXIS([0 10 -40 1]);
xlabel('f in kHz')
ylabel('Y(2*pi*f) in dB')
title('output (digital) signal spectrum (Hamming Window)');
L=201;   
n=0:L-1;
subplot(2,2,2);
bar(n,yn,0);
title('output (digital) signal ');