Time-varying higher order spectra

Boualem Boashash; Peter O'Shea

doi:10.1117/12.49815

1 December 1991 Time-varying higher order spectra

Boualem Boashash, Peter O'Shea

Proceedings Volume 1566, Advanced Signal Processing Algorithms, Architectures, and Implementations II; (1991) https://doi.org/10.1117/12.49815
Event: San Diego, '91, 1991, San Diego, CA, United States

Abstract

A general solution for the problem of time-frequency signal representation of nonlinear FM signals is provided, based on a generalization of the Wigner-Ville distribution. The Wigner- Ville distribution (WVD) is a second order time-frequency representation. That is, it is able to give ideal energy concentration for quadratic phase signals and its ensemble average is a second order time-varying spectrum. The same holds for Cohen's class of time-frequency distributions, which are smoothed versions of the WVD. The WVD may be extended so as to achieve ideal energy concentration for higher order phase laws, and such that the expectation is a time-varying higher order spectrum. The usefulness of these generalized Wigner-Ville distributions (GWVD) is twofold. Firstly, because they achieve ideal energy concentration for polynomial phase signals, they may be used for optimal instantaneous frequency estimation. Second, they are useful for discriminating between nonstationary processes of differing higher order moments. In the same way that the WVD is generalized, we generalize Cohen's class of TFDs by defining a class of generalized time-frequency distributions (GTFDs) obtained by a two dimensional smoothing of the GWVD. Another results derived from this approach is a method based on higher order spectra which allows the separation of cross-terms and auto- terms in the WVD.

Citation Download Citation

Boualem Boashash and Peter O'Shea "Time-varying higher order spectra", Proc. SPIE 1566, Advanced Signal Processing Algorithms, Architectures, and Implementations II, (1 December 1991); https://doi.org/10.1117/12.49815

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