针对平面接收阵阵元数量庞大导致的水下三维声学成像系统硬件开销和计算量过大的问题，提出了一种基于十字型阵列的三维声学成像的多频发射波束形成算法． 该算
法将发射波束方向划分为多个扇面，在每个扇面内依次向各波束方向发射不同频率的扇形波束信号，将发射次数从波束数减少到扇面数，从而缩短了扫描时间． 仿真实验和计算量分析表明，文中算法能够获得与平面接收阵直接波束形成算法相同的波束性能，并且大幅降低了阵元数量和计算量． 实际水下试验证明了该算法能够满足水下三维声学成像的实时性需求．
In order to solve the problems of the huge hardware cost and computational load in underwater 3D acoustic imaging system,which is caused by the large number of elements in a receiving planar array,a multi-frequency transmitting beamforming algorithm is proposed for the real-time 3D acoustic imaging on the basis of cross array.In the algorithm,first,transmitting steering directions are subdivided into several sectors.In each sector,a series of fan-shaped beams with different frequencies are transmitted sequentially,and each beam is steered to a specific direction.Then,the number of transmissions is reduced from the number of beams to the number of sectors,thus shortening the scanning time.Simulation results and the analysis of computational load show that the proposed algorithm can obtain the same performance as the direct beamforming method on the basis of the receiving planar array and dramatically reduce both the transducer number and the computational load.Real underwater experiments demonstrate that the proposed algorithm can meet the real-time requirement in underwater 3D acoustic imaging applications.
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