50 pages ; International audience ; Sofware: Decomposition of signals into contributions of "wavelets": Program documentation "Ondel". The wavelet transform is a method allowing to analyze and re-synthesize an arbitrary signal s(p) into elementary contributions or function called "wavelets". All "wavelets" have same shape and are obtained by translation and dilation (or compression) of a "mother" wavelet (analyzing wavelet) g(p). They constitute a two-parameters family. Each wavelet has limited support in both time and frequency domain. This transformation allows to analyze a signal retaining the characteristics of time and frequency. The signal energy is itself preserved. We will define the concept of wavelet in the case of one-dimensional signals (p could be the quadri-vector space-time).