%% Periodogram Using Default Inputs
% Obtain the periodogram of an input signal consisting of a discrete-time sinusoid with an angular frequency of \pi/4 rad/sample with additive N(0,1) white noise.
% Create a sine wave with an angular frequency of \pi/4 rad/sample with additive N(0,1) white noise. The signal is 320 samples in length. Obtain the periodogram using the default rectangular window and DFT length. The DFT length is the next power of two greater than the signal length, or 512 points. Because the signal is real-valued and has even length, the periodogram is one-sided and there are 512/2+1 points.

n = 0:319;
x = cos(pi/4*n)+randn(size(n));
[pxx,w] = periodogram(x);
plot(w,10*log10(pxx))

%
% Repeat the plot using periodogram with no outputs.

periodogram(x)

% Copyright 2015 The MathWorks, Inc.