The example presented in Sections 3.1 to 3.5 illustrated the basic mechanics of calculating the DFT coefficients for a given set of timeseries data. In practice, the transition from DFT coefficients to any kind of frequency-domain analysis requires attention to many details, most of which are not necessarily intuitive. For example, several opportunities for pre-processing the data series before calculating the DFT can be implemented to enhance certain features of the resulting power spectrum. The first few sections of this chapter discuss some common pre-processing steps for producing better DFT periodogram estimates of a time-series signal’s frequency content. Although periodograms are very useful, the DFT coefficients can also be exploited for more incisive analyses, some of which are discussed in the later sections in this chapter.
Pre-Processing and Other Tricks of the DFT Trade