%% Noise Power
% Create a sinusoidal signal sampled at 48 kHz. The signal has a fundamental of frequency 1 kHz and unit amplitude. It additionally contains a 2 kHz harmonic with half the amplitude and additive noise with variance 0.1².

fs = 48e3;
t = 0:1/fs:1-1/fs;

A = 1.0;
powfund = A^2/2;
a = 0.4;
powharm = a^2/2;
s = 0.1;
varnoise = s^2;

x = A*cos(2*pi*1000*t) + ...
    a*sin(2*pi*2000*t) + s*randn(size(t));

%
% Compute the noise power in the signal. Verify that it agrees with the definition.

[SNR,npow] = snr(x,fs);
compare = [10*log10(powfund)-npow SNR]

% Copyright 2012 The MathWorks, Inc.