ANGLE-OF-ARRIVAL ESTIMATION OF PLANE-WAVES PROPAGATING IN RANDOM-MEDIA

The well-studied problem of estimating the angle of arrival of plane w aves in ocean acoustics is revisited. While beamforming is the classic al technique, the most recent methods use parametric models of the sig nals, and maximum likelihood estimation (MLE). Yet, in all cases, fluc tuations in the required signals due to medium perturbations have been neglected. In this paper, the advantages of using the correct second moment for waves propagating in random media (WPRM) to model the fluct uations of the arriving signals are investigated. In this way, the phy sics of WPRM is incorporated in this parametric model of the observati ons. This model is then used as the basis for the MLE. Finally, the Cr amer-Rao lower bound versus fluctuation strength, angle of arrival, an d the noise power is provided. Also developed are iterative ML algorit hms based on the Newton-Raphson method for a single source and extende d to multiple sources. The method is applicable for plane wave arrival s at any known array geometry with arbitrary medium autocorrelation fu nction. Simulation results show a dramatic improvement in the precisio n of the estimated angle of arrival. (C) 1996 Acoustical Society of Am erica.