fg_05_09.m

英文书《Digital Signal Processing with Examples in MATLAB》附带的MATLAB实例

% fg_05_09  FIR lowpass power spectra.
N=127; dB0=-120; vc=0.1;
name=str2mat('Hamming','Kaiser; \beta=5.44','Blackman',...
             'Kaiser; \beta=8.89');
beta=[sqrt(3)*pi 2*sqrt(2)*pi];
windo=[5,0; 7,beta(1); 6,0; 7,beta(2)];
nu=linspace(0,.5,500);
clr=['r' 'r' 'c' 'c'];
sp_fig(1);
for i=1:4
   w=fir_weights(N,1,windo(i,:),vc);
   H=fft([w,zeros(1,1000-N)]);
   dB=20*log10(max(abs(H(1:500)),-log10(-dB0/2)));
   subplot(2,2,i);
   axis([0 .5 dB0 0]);
   line(nu,dB,'color',clr(i));
   grid;
   set(gca,'fontsize',16);
   if(i==3|i==4)
      xlabel('\nu (Hz-s)');
   end
   if(i==1|i==3)
      ylabel('dB');
   end
   ht(1)=text(.21,-10,name(i,:));
   set(ht,'fontsize',16);
end