%sigpwgn1.m
display('Running...sigpwgn1');

t = 0:0.015:10 ;     % Time vector
x = sin(7*t);        % Signal

%add white gaussian noise 
sigma=0.2;
L=length(x);
n=randn(1,L);
y=x+sigma*n;    %signal plus noise  

%plot time domain
subplot(2,1,1)
plot(t,y), title('signal - time domain');
 
%FFT
ffty = fft(y);                             % Compute DFT of y
my = abs(ffty); py = unwrap(angle(ffty)); % Magnitude and phase

f = (0:length(ffty)-1)/length(ffty); % Frequency vector
subplot(2,1,2)
plot(f,my); title('signal - frequency domain');