双侧回波联合的合成孔径声呐运动补偿算法

利用单侧回波可估计合成孔径声呐基阵的斜距误差,但无法区分横荡误差和升沉误差。针对此问题,提出了一种双侧回波联合的运动补偿方法。该方法首先根据双侧基阵运动误差的几何关系,建立了双侧基阵的运动误差模型,再结合偏移相位中心算法估计基阵的横荡误差和升沉误差,最后利用所估计的运动误差对不同掠射角上的回波进行运动补偿。仿真结果表明:该方法能精确估计双侧基阵的运动误差,其估计值与实际值的偏差为10-4 m左右,估计结果的标准差接近克拉美罗下界;对回波进行运动补偿后,能获得比基于单侧回波运动补偿方法更好的成像效果。水下球串目标的湖试数据的成像结果显示,与基于单侧回波的运动补偿方法相比,所提方法能更好地抑制图像的散焦现象。 

Synthetic aperture sonar motion compensation algorithm using dual-sided echo

The slant-range error of the synthetic aperture sonar array can be estimated by using the single-sided echo,but the sway and the heave cannot be distinguished.Aiming at this problem,a motion compensation method using dual-sided echoes is proposed.Firstly,the motion errors model of the dual-sided array is established based on the geometric relationship of the dual-sided array motion errors.Then,sway and the heave are estimated by combining the displaced phase center algorithm.Finally,motion compensation is performed for echo signals at different grazing angles using the estimated motion errors.The simulation result shows that the proposed method can accurately estimate the motion errors of the dual-sided array,the deviation between the estimated value and the actual value is about 10-4 m,and the standard deviation of estimated results is close to the Cramer-Rao lower bound.After the motion compensation,a better imaging can be obtained.The imaging results of the lake test data of the underwater ball string target show that,compared with the motion compensation method based on single-sided echo,the proposed method can suppress defocusing more effectively.