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Direction-of-arrival estimation using high-order superdirective beamforming for a circular hydrophone array

This paper presents a method of direction-of-arrival estimation using the high-order superdirective beamforming for a circular hydrophone array. The weighting vectors with different orders used for DOA estimation can be obtained using the previously proposed eigenbeam decomposition and synthesis theory, which can provide frequency-invariant beampatterns in a wide frequency band. The DOA estimation result of this method is the sum of estimations with different orders and the robustness decreases with an increase of the number of order. The reduced-rank technique is applied to achieve robust DOA estimations by truncating some error-intolerable high order estimation results and reserving the low order ones. Simulation results show that the DOA method proposed in this paper can improve the angular resolution (when the sensor space to wavelength ratio is smaller than 1/2) compared to the conventional beamforming (CBF) method. An experiment was conducted in the South China Sea with a 12-hydrophone circular array, and the results show effectiveness and validity of the proposed method.