1. Wavelet bases

Many physiological signals can reasonably be characterized as isolated pulses or as sequences of pulses. For this reason, wavelet-based signal processing techniques appear, for these signals, as interesting alternatives to Fourier transform techniques. The fact that wavelet bases have a compact or essentially compact support (i.e. a base of elements of finite or effectively finite duration) guarantees that at least some of the candidate wavelet representations of these quasi-impulse signals will converge faster than their corresponding Fourier series representation. This elementary property has been expressed in more sophisticated terms: for example, the process of taking a wavelet transform "decorrelates" a signal by concentrating its energy on a relatively small number of coefficients