Time-frequency distributions of energy of the simulated signal (here plotted as a) from Fig. 7. (b) and (c) present spectrograms (i.e. windowed or short-time Fourier transforms) calculated, respectively, for long (125 points) and short (21 points) windows. (d) is a scalogram (continuous wavelet transform), (e)-smoothed pseudo Wigner-Ville distribution, (f)-the same as (e) in 3 dimensions.