3. 1st signal processing step: signal analysis and estimation

Signal analysis is a broad concept, covering all aspects of extracting information from a signal. Analysis is often inseparable from representation, as a well-chosen representation can more easily reveal a given characteristic. This is particularly true of the Fourier representation, for certain classes of signals. As an example, consider two wind instruments (a clarinet and a trombone) playing the same note. The signal plots themselves are not very informative, but the spectra (the squared moduli of their Fourier transforms) are, as shown in figure 12 . We can clearly see peaks corresponding to the fundamental frequency and harmonics (frequencies that are multiples of the fundamental frequency). It's quite clear that in either case, the fundamental frequency can easily be estimated...