浅海低速弱目标低频主动空时自适应适配处理方法

The spatial and timal changes of underwater environment and the changes of signal parameters of active Sonar will result in the changes of spatial-timal statistical characteristic of reverberation received by moving platform, which will bring on the mismatch between structure fixed space time adaptive processing (STAP) systems and environments or parameters and then the performance decreases. Based on the analysis of degree-of-freedom (DOF), this item studies the adaptive adaptation of shallow water active Sonar STAP to environments or parameters and upgrades the information acquisiting ability of active Sonar in shallow water environment. The research fingings have important significance to navy underwater information warfare, and have important academic value to the deelopment of active Sonar techniques and the richness of STAP theory under shallow water reverberation circumstance...This item takes the DOF as breakthrough point. Firstly, characterization for DOF of reverberation under different shallow water conditions is studied, and then relationship between DOF and performance of STAPs is constructed for the design of STAP algorithms with adaptive DOF adaption, which will improve the performance by 2-3 dB according to the conventional STAPs. Secondly, the theory and technical implement of the multiple pulse cumulation based STAPs are studied, which will improve the performance by 1-2 dB according to the single pulsed STAP on the baisi of adaptive adaptation. Thirdly, the effect degree of errors for STAPs are studied and robust STAPs are constructed by adding restricting terms or improving the accurate of covariance matrix under small samples. It is expected that the robust STAP can improve performance by about 3dB than the conventional STAPs with errors.

水声环境的时变空变以及主动声纳发射信号参数的变化，导致运动平台混响空时统计特性改变，使得系统结构固定的空时自适应处理（STAP）系统与环境、参数等失配、性能下降。本项目以自由度分析为基础，研究浅海环境低频主动声纳STAP对环境、参数等自适应适配问题，提升主动声纳在浅海环境中的信息获取能力。成果对海军水下信息作战有重要意义；对低频主动声纳技术发展与浅海混响条件下STAP理论丰富有重要学术价值。..以自由度分析为切入点。首先研究浅海不同条件下混响自由度表征，建立自由度与STAP性能的关联，使基于系统自由度自适应适配的STAP较现有STAP性能提升2-3dB；其次研究基于多脉冲累积的STAP原理及技术实现，在适配基础上使性能较单脉冲STAP提升1-2dB；第三进行STAP误差影响分析，从增加约束和提高小样本协方差矩阵准确性角度构建稳健型STAP，使其性能较现有STAP在存在误差时提升1-3dB。

本项目的研究，解决了空时自适应处理（STAP）方法对混响环境自适应适配的科学问题，以便发挥STAP方法在空间锥角—多普勒域上有效辨识混响和慢速弱目标的优势。.项目以自由度分析为切入点。首先研究浅海不同条件下混响自由度表征，建立了自由度（混响、系统）与混响抑制性能之间的解析关系--平均最优处理增益正比于实际的空时观测数和混响自由度与系统自由度之比；以性能较为稳健的局域联合（JDL）方法为基础，采用适配不同的局域大小来自适应适配混响自由度，系统自由度自适应适配混响自由度后，其性能明显优于非自适应适配STAP，性能提升不低于3dB；再次，在多ping数据统计特性分析的基础上，构建了多ping 累积STAP方法，采用仿真数据验证，较单ping STAP性能提升2-3dB；采用基于核密度估计（kernel density estimation, KDE）的空-时处理方法后，多ping 累积处理的性能提升大约6dB；在协方差矩阵估计方面，着重开发少数据样本支持算法，仿真分析表明转角重排和对角加载联合使用的性能较好，实验数据分析发现性能提升有约10dB；阵列误差的宽容性设计方面，采用分段拟合方式，可得较好性能，仿真和实验数据表明有2-3dB的性能改善。.以上关键技术的突破可以很好地自适应适配环境的变化，也为STAP向工程化方向推进了一步。未来，研究成果具有较高的军事应用价值，有应用于水下慢速运动目标的探测可能。