Figure 7

Time-frequency map of energy density of a 500-points simulated signal (e) composed of four sine-modulated Gaussians, i.e. Gabor functions (a-b), sine wave and one-point discontinuity (c) and sine wave with linear frequency modulation-chirp (d). Distribution (f) was obtained from a decomposition in a large (2 * 10⁶ waveforms) dictionary. Changing frequency of the chirp is represented as a series of functions, since in the Gabor dictionary (section 5) we have only constant frequency modulations, (g)-the same as (f), presented in 3 dimensions. Square root of energy proportional to the height of the surface or "temperature" on 2-dimensional plots. [22]