Dynamical power spectrum showing the proper frequencies of the tested systems as functions of the mean-motion ratio. The smooth evolution of the frequencies is characteristic of regular motion and occurs around n₁/n₂ = 1.33 (4/3 MMR) and n₁/n₂ = 1.5 (3/2 MMR). The erratic scattering of the points in the other domains is characteristic of the chaotic motion. The nominal location of several high-order MMR is shown.