Volumetric Array Beamforming Research

As airborne dipping sonar and sonar buoy developing toward low frequency and multi static, new kind of array such as volumetric array emerged which can provide larger aperture than before. Volumetric array beam forming (VABF) catalog to arbitrary array beam forming technology. In this paper we systematically research VABF method according to sonar development project. Research result state as following.1. Introducing basic method of arbitrary array beam forming include delay and sum beam forming and minimum variance distortionless response(MVDR) beam forming. Start form MVDR, we develop a new approach, Adaptive optimization beam forming (AOBF) which can reach desired sidelobes level. As an example, we give AOBF result of a circle array though computer simulation.2. After discussing basic concept of volumetric array, we apply AOBF to volumetric array, given detailed numerical pattern synthesis formulas and algorithm. In this paper we supposed three typical volumetric array, computer simulation shows AOBF can create very good beams with sidelobes below -30dB compared with nearly -8dB sidelobes level though delay and sum beamforming.3. The designed patterns for perfect volumetric arrays will suffer much distortion in the presence of array mismatch errors. To avoided model mismatch, array manifold can be valued though field test. Using test array manifold instead of perfect array model , model mismatch is reduced . We test two kind of volumetric array's array manifold, AOBF create robust beam forming which meet the requirement of project.