fg_10_28.m

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

% fg_10_28        Octave band decomposition.
K=20000; T=1/40000; skp=5000; ftr=['1';'2';'3';'4'];
% 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(1,9,5);
subplot(2,1,1);
set(gca,'fontsize',14);
line([0:N-1]*T,x,'color','r'); grid on;
axis([0 (N-1)*T -150 150]);
ylabel('x(t)');

L=[N/8 N/8 N/4 N/2];
y=zeros(N,4);
u1=qmf(x,31,5);
y(1:N/2,4)=u1(:,2);
u2=qmf(u1(:,1),31,5);
y(1:N/4,3)=u2(:,2);
u3=qmf(u2(:,1),31,5);
y(1:N/8,2)=u3(:,2);
y(1:N/8,1)=u3(:,1);

msg=char('x^{LLL}','x^{LLH}','x^{LH}','x^{H}');
for i=1:4,
   subplot(2,4,4+i);
   set(gca,'fontsize',14);
   line([0:L(i)-1]*N*T/L(i),y(1:L(i),i),'color','b');
   grid on;
   axis([0 (N-1)*T -100 100]);
   text(.015,80,msg(i,:),'fontsize',14);
   xlabel('time (s)');
end