低频共形阵的宽带波束域高分辨方位估计方法

针对共形布阵技术,提出了适用于低频共形基阵的宽带波束域高分辨方位估计方法。首先利用基于二阶锥规划的波束优化技术设计适用于低频共形基阵的宽带恒定束宽波束形成器,然后用设计好的波束形成器对基阵输出数据进行空域预滤波,使宽带信号的不同频率分量能无失真地通过,同时抑制旁瓣区的干扰,最后针对滤波后的多波束输出采用波束域高分辨方位估计方法估计目标方位。由于基于二阶锥规划技术设计恒定束宽波束形成器仅需要对主波束进行拟合,提高了设计精度,减小了聚焦误差,从而提高了方位估计的性能。计算机仿真和湖上实验数据处理结果验证了该方法能有效地估计出水下低频宽带目标声源的方位。

Broadband beamspace DOA estimation algorithms for low frequency conformal array

Beam-space MUSIC for direction of arrival estimation of underwater broadband targets with low frequency is presented for conformal array. Firstly, broadband constant beamwidth beamforming (BCBB) weights are designed via array pattern synthesis based on second-order cone programming (SOCP) at each frequency bin in bands of interest. Then, the output data at the array elements from broadband sources in different directions pass through the BCBB that direct multiple directions at adjacent region of the DOA (direction of arrival). Finally, high resolution algorithms are used for fine DOA estimation. Because designed beampattern have same beamwidth in the mainlobe region and low sidelobe level at each frequency bin, therefore, the wideband source can be received without distortion, at the same time, interfering signals from sidelobe region can be suppressed more effectively. Accordingly, the performance of high resolution DOA estimation algorithms in beamspace processing is guaranteed. Results of computer simulation and lake-experiment show that beampattern with constant beamwidth and desired sidelobe level can be effectively formed by BCBB, moreover, DOA estimation of underwater broadband targets can be attained accurately for low frequency conformal array.