The application of the fast Fourier transform algorithm to the estimation of spectra and cross-spectra

Alternative methods for the estimation of spectra are described and compared. Some of these methods have only become practicable with the advent of the fast Fourier transform algorithm although all of them benefit from the computational speed and accuracy of the algorithm. Topics discussed in relation to these methods for estimating spectra are spectral windows and bias in the estimates, general questions of statistical variability, the use of regression methods to smooth the periodogram, and use of time sectioning of the data to either smooth or to investigate non-stationarities in the data. The use of these methods and the fast Fourier transform algorithm for estimating cross-spectra is discussed briefly. © 1970.