The evanescent field transform for estimating the parameters of homogeneous random fields with mixed spectral distributions

Parametric modeling and estimation of complex valued homogeneous random fields with mixed spectral distributions is a fundamental problem in two-dimensional (2-D) signal processing. The parametric model under consideration results from the 2-D Wold-type decomposition of the random field. The same model naturally arises as the physical model in problems of space-time adaptive processing of airborne radar. A computationally efficient algorithm for estimating the parameters of the field components is presented. The algorithm is based on a nonlinear operator that uniquely maps each evanescent component to a single exponential. The exponential's spatial frequency is a function of the spectral support parameters of the evanescent component. Hence, employing this operator, the problem of estimating the spectral support parameters of an evanescent field is replaced by the simpler problem of estimating the spatial frequency of a 2-D exponential. The properties of the operator are analyzed. The algorithm performance is illustrated and investigated using Monte Carlo simulations.