A generic generation of 1/f noise in locked systems working in nonlinear mode

Properties of the phase fluctuations of a nonlinear oscillator is investigated using experimental setups which simulate the same behavior. The multiscale aspect of synchronization is experimentally confirmed with the observation of lockings between rational ratios. This global property of synchronization is associated to a local one by the study of the Phase Locked Loop (PLL) under nonlinear behaviors. We show that the discontinuity between the locking and the free-run behavior is characterized by the presence of slow temporal variables which induce a low frequency spectrum. An experimental verification of the increase in the spectrum confirms the classical results which associate 1/f noise to nonlinearity, autosimilarity and regularity represented here by the synchronization.