Interference Suppression Based on Virtual Array Elements Expansion on the Small-Scale Underwater Acoustic Array

For the acoustic arrays on underwater unmanned vehicle, the small scale of the platform restricts the array aperture, which limits the resolution and signal-to-noise ratio (SNR) gain of the array, resulting in poor direction of arrival (DOA) estimation performance. In order to identify the target signal received by the small-scale array, an interference suppression method based on double virtual array elements expansions is proposed to accurately estimate the target signal azimuth. Firstly, based on the received data of the actual array elements, the first expansion of the virtual array elements is performed to estimate the DOA of the interference signal, and the interference signal is cancelled according to the estimated value. Then the actual array elements after interference cancellation are extended for the second time to estimate the angle of the target. The simulation results show that the interference signal is suppressed after double virtual array element expansions, and the beam formed based on the virtual array elements has a narrower main lobe in the target direction than that of the conventional beamforming.