ABSTRACT
In this section, the spectral analysis method is introduced as a basic tool
for stationary time series analysis. By means of spectral analysis, we
can capture the characteristics of time series by decomposing time se-
ries into trigonometric functions at each frequency and by representing
the features with the strength of each periodic component. The subjects
discussed here will lead to the definition of the power spectrum and the
periodogram of time series, computational methods, variance reduction
and smoothingmethods.Moreover, an efficient method of computing pe-
riodograms is presented using fast Fourier transforms (FFT). The readers
interested in the spectral analysis of time series are referred to Brillinger
(1974), Bloomfied (1976), Akaike and Nakagawa (1989) and Brockwell
and Davis (1991).