Performance Analysis for Focused Beamformers in Passive Underwater Acoustic Localization

Focused beamformers are widely used in passive underwater acoustic localization. Many pseudo-peaks (spurious peaks not corresponding to a real source) are produced by focused beamformers, impacting the performance and reliability of related algorithms. After describing both the received signal model of near-field sources with a uniform line array, and the basic principle of passive localization based on focused beamformers, we define pseudo-peaks in the focused beamformer's spectra and give the procedure to quantify these pseudo-peaks. The performance of conventional focused beamformers (C-FBs) and minimum variance distortionless response focused beamformers (MVDR-FBs) are studied, focusing on the number of pseudo-peaks in passive underwater acoustic localization. After establishing a simulation model based on an underwater acoustic environment, the algorithms are compared in terms of signal-to-noise ratio, frequency, distance of the source signal, and detection threshold. In all cases, the MVDR-FB method shows superior performance to the C-FB method in minimizing the number of pseudo-peaks. Finally, a method of selecting the detection threshold based on the convergence of pseudo-peak number is proposed.