fg_08_18.m

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

% fg_08_18          Signal plus noise.
K=40000; T=1/40000;

% Copy the speech signal.
fid=fopen(['signal_3.txt']);
s=fscanf(fid,'%7d%8d%8d%8d%8d%8d%8d%8d%8d%8d\n',K);
fclose(fid);
s=127*s'/max(abs(s));

% Generate the rivet gun noise.
b=[1 zeros(1,99) -.99];
a=[1 -2*.99*cos(2*pi*2/100) .99^2];
randn('seed',0);
noise=filter(b,a,10*rand(1,40000));

snr_dB=10*log10((s*s')/(noise*noise'))

% Plot signal plus noise.
sp_fig(1,9,5.5);
set(gca,'fontsize',16);
line([0:K-1]*T,s+noise,'color','r'); grid on;
axis([.2 .5 -500 500]);
xlabel('t (s)'); ylabel('s(t)+n(t)');