Two-dimensional cubic nonlinear coupling estimation in correlative multiplicative noise

A special fourth-order time-average moment spectrum approach is proposed for estimating two-dimensional (2-D) cubic nonlinear coupling. It can be applied to obtain the coupled and coupling frequencies in the noise that multiplicative and additive noises of any mean are mutually independent, and the multiplicative noises are correlative. In the meantime, this method needn't constrain the distribution and the color of noises. Simulation examples illustrate the algorithms.