denoise.m

matlab 源程序

%example of Fourier transform of a signal
t = 0:1e-2:10;

%sinusoid signal
y = cos(2*pi*t);

%white Gaussian noise
n = randn(1, length(y));

%add noise to the signal
y = y+n*2;

%plot signal in the time domain, the signal is hardly perceivable
plot(t, y);

%take the Fourier transform
f_y = abs(fft(y));

%the frequency of the sinusoid signal is still significantly larger than
%other frequency components
plot((1:length(f_y))/length(f_y), f_y);