The power spectrum of a
time series ![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!ARV6FUJ2JP&type=0&index=512)
describes the distribution of frequency components composing that signal. According to
Fourier analysis any physical signal can be decomposed into a number of discrete frequencies, or a spectrum of frequencies over a continuous range. The statistical average of a certain signal or sort of signal (including
noise) as analyzed in terms of its frequency content, is called its
spectrum.