Comparison of extended Kalman filtering with split‐aperture processing for angle of arrival estimation in multibeam echo‐sounding

Echo angle of arrival estimates may be obtained from the FFT beamformed output of a multibeam sonar system at each successive time sample. Whether tracking disparate targets in the water column or tracking a mostly continuous surface such as the seafloor, the sequence of angles of arrival versus time is inherently nonlinear and nonstationary, and lends itself to processing with an extended Kalman filter. This filter provides both an approximation of the optimum (in a least squares sense) angles of arrival estimation and a measure of the associated errors. This technique is applied to quadrature‐sampled field data collected with the 26‐element hydrophone array of a 160‐kHz multibeam sonar system. Results are compared to arrival angle estimates obtained with a conventional split‐aperture processor. [Work supported by NOAA Grant 111833.]