%% Single-Sided Amplitude Spectrum of Signal
% Find frequency components of a signal in additive noise.
% Note: This example runs only in R2016b or later. If you are using an earlier release, replace each call to the function with the equivalent  step syntax. For example, myObject(x) becomes step(myObject,x).

Fs = 800; L = 1000;
t = (0:L-1)'/Fs;
x = sin(2*pi*250*t) + 0.75*cos(2*pi*340*t);
y = x + .5*randn(size(x)); % noisy signal
ft = dsp.FFT('FFTLengthSource','Property', ...
    'FFTLength',1024);
Y = ft(y);

%
% Plot the single-sided amplitude spectrum

plot(Fs/2*linspace(0,1,512), 2*abs(Y(1:512)/1024))
title('Single-sided amplitude spectrum of noisy signal y(t)')
xlabel('Frequency (Hz)'); ylabel('|Y(f)|')