Performance comparison of the Wagstaff–Berrou and maximum entropy method beamformers

Abstract

The performances of the maximum entropy method (MEM) and Wagstaff–Berrou broadband (WB2) high-resolution spatial processing techniques are compared with each other and with the conventional fast Fourier transform (FFT) beamformer. The comparisons are based on the analysis of three sets of measurements acquired at sea during two different environmental acoustics field exercises. Chosen for comparison are the effects of signal-to-noise ratio (SNR) on beamwidth and the effect of the number of array elements on the bearing estimation accuracy and beamwidth of the spatial processors. Results from these data indicate that both of the high-resolution methods yield smaller beamwidths than the conventional FFT processor, and that the high-resolution beamwidths show little dependence on SNR for values greater than 8 dB at the hydrophone input. Also, MEM beamwidths are generally slightly smaller than WB2 beamwidths and show less dependence on aperture. Measured MEM beamwidths show the same general trend as theoretical calculations for sensitivity to SNR, and the average arrival angles of all three beamformers show the same general dependence on the aperture.