fg_05_11.m

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

% fg_05_11 low, high, bandpass, and bandstop FIR power spectra.
N=127; H0=1.e-6;
w=[7,2*sqrt(2)*pi];
b_lp=fir_weights(N,1,w,.1);
b_hp=fir_weights(N,2,w,.4);
b_bp=fir_weights(N,3,w,.1,.2);
b_bs=fir_weights(N,4,w,.1,.2);
B=[b_lp;b_hp;b_bp;b_bs];
name=str2mat('Lowpass','Highpass','Bandpass','Bandstop');
clr=['r' 'g' 'b' 'c'];
nu=linspace(0,.5,500);
sp_fig(1);
for i=1:4
   H=fft(B(i,:),1000);
   dB=20*log10(max(abs(H(1:500)),H0));
   subplot(2,2,i);
   axis([0 .5 20*log10(H0) 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