fg_10_27.m

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

% fg_10_27        Equal band decomposition.
K=20000; T=1/40000; skp=5000;
% Copy the speech signal.
fid=fopen(['signal_3.txt']);
x=fscanf(fid,'%7d%8d%8d%8d%8d%8d%8d%8d%8d%8d\n',K);
fclose(fid);
x=127*x(skp+1:K)'/max(abs(x(skp+1:K)));
N=length(x);

sp_fig(1);
subplot(3,1,1);                             % original signal
set(gca,'fontsize',14);
line([0:N-1]*T,x,'color','r'); grid on;
axis([0 (N-1)*T -150 150]);
ylabel('x(t)');

u1=qmf(x,31,5);
msg=char('x^L','x^H');
for i=1:2,
   subplot(3,2,2+i);                        % L,H
   set(gca,'fontsize',14);
   line([0:N/2-1]*2*T,u1(:,i),'color','g'); grid on;
   axis([0 (N-1)*T -100 100]);
   text(.01,70,msg(i,:),'fontsize',14);
end

msg=char('x^{LL}','x^{LH}','x^{HL}','x^{HH}');
for n=1:2,
   u2=qmf(u1(:,n),31,5);
   for i=1:2,
      subplot(3,4,6+2*n+i);                 %LL,LH,HL,HH
      set(gca,'fontsize',14);
      line([0:N/4-1]*4*T,u2(:,i),'color','b'); grid on;
      axis([0 (N-1)*T -100 100]);
      text(.01,70,msg(2*n+i-2,:),'fontsize',14);
      xlabel('t (s)');
   end
end