The use spectral and bispectral analysis for diagnosis of nonlinear dissipative medium

It is well known that during the propagation of a noise wave in a nonlinear medium the spectral composition of the field as well as the higher statistical characteristics of the wave (multipoint probability distribution, higher moments, and cumulants) change. The object of the present study also is a numerical analysis of the spectral and bispectral functions of the intense regular and random signals propagating in nondispersivc nonlinear media. LabVIEW environment is extremely simple in use, and provides good results as compared to traditional programming techniques. For example, internal libraries make it easy to take direct and inverse Fourier transform, as well as regular and random signals. The possibility of recovering the input spectrum from the measured spectrum and bispectrum at the output of the nonlinear medium is discusses. The analytical estimations are supported by numerical simulation. For two different types of primary spectrum evolution of flat random waves were numerically simulates at a short distance and assayed bispectrum and a spectrum analysis of the signals. This model is a virtual instrument which can solve some diagnosis problems using spectral and bispectral processing tools.