SPECTRAL ANALYSES OF NONLINEAR-INTERACTIONS

Signals pertaining to motions of a non-linear oscillator and a set of quadratically coupled oscillators are studied using higher-order spect ral analyses. The analyses are used to understand the role of phase co upling in non-linear interactions betwen two or more Fourier component s. For certain motions of weakly non-linear systems, analytical approx imations are obtained for the relevant higher-order spectra and cohere nce functions. The analytical approximations are useful in understandi ng the dependence of bispectra on the non-linearities. Numerical studi es are conducted to verify analytical predictions and to illustrate th e usefulness of spectral analyses for different cases. (C) 1996 Academ ic Press Limited