Figure 7.

Decomposing a synthetic FM sweep into its ripple components. A, A spectrogram of a synthetic, downward FM sweep moving at a constant velocity indicated by its slope. B, Magnitude matrix of the FM sweep shown in A obtained by the two-dimensional Fourier transform of its spectrogram. Because FM velocity is equal to the ratio of temporal to spectral modulation rates (TMR/SMR), the ripple composition of the sweep clusters around a line passing through the origin (0,0) with a slope that indicates the FM velocity of the sweep.