Edmund J. Sullivan
Code 103, Naval Undersea Warfare Center, Newport, RI 02841
Geoffrey S. Edelson
Univ. of Rhode Island, Kingston, RI 02881
The bispectrum is the expected value of the third-order cumulant of the data sequence of a signal in either space or time. Much analysis based on the bispectrum has already been carried out in the time domain, where information regarding the stationarity, linearity, and Gaussianity of the signal series can be analyzed. In this paper, it is shown that these concepts can be directly applied to the spatial domain, resulting in a generalization of the standard k-(omega) beamformer. It is shown that the ability of the bispectrum to indicate nonstationarity in the data series allows this generalized beamformer to account for nonplanar aspects of the incoming signal wave front, thereby allowing for source localization in which bearing and range estimation evolve in a self-consistent framework. Thus bearing estimation and wave front curvature ranging appear as special cases. It is also shown that the technique is applicable to the analysis of more complicated propagation scenarios such as normal mode propagation.