Detection of quadratic interaction in signals using the Wigner bispectrum

It is demonstrated that, under certain conditions which may be quite restrictive, the Wigner bispectrum, based on cumulants, may be used to detect quadratic phase couplings in signals generated from a class of time-varying nonlinear systems. It is shown that for the class of systems considered, the Wigner bispectrum yields a shifted bispectrum. Such an analysis would prove useful for analyzing such nonstationary signals