海杂波中弱目标微动特征提取及检测技术研究

The attitude of target at sea may vary with the fluctuation of sea surface and induce the effect of power modulation of radar echo. Then the Doppler reflects time-varying and nonstationary properties for the simultaneous translation and rotation movement. In this case, the research intends to apply micro-Doppler theory to weak target detection within sea clutter and systematically study the modelling methods of sea clutter and target with micro-motion at sea, the enhancement and extraction methods of micro-motion properties, et. al.. The differences of micro-motion properties between sea clutter and weak target at sea will be employed to propose detection methods for weak target in sea clutter, which can be provided for further improvement of detection abilities of low observable target at sea. The research methods include: (1) modelling of non-Bragg scattering of sea clutter and target with micro-motion at sea; analysis of micro-motion properties in time domain, polarization domain, transform domain (frequency, FRFT and HHT domain) and sparse domain; (2) enhancement, extraction and parameter estimation of micro-motion properties using polarization characteristics decomposition, transform methods (FRFT, short time FRFT, factional ambiguity, HHT and their improvement) and parameterization methods (time-varying parameter model and sparse representation); (3) finding the micro-motion properties which can reflect the existence of target at sea; forming the test statistics based on micro-motion properties for constant false alarm detection; verification and performance analysis with real sea clutter data.

海上目标随海面颠簸导致姿态变化，引起回波功率调制效应，同时存在平动和转动，导致回波多普勒特征体现时变和非平稳特性。为此，本项目拟将微多普勒理论应用于海杂波中弱目标检测，系统研究海杂波和海面微动目标回波建模方法，微动特征的增强与提取等技术，利用海面弱目标与海杂波的微动特征差异，提出目标检测方法，为进一步提高对低可观测海面目标的检测能力提供新思路。拟采取的研究方法：1）海杂波非Bragg散射回波和海面微动目标回波建模，并分析两者在时域、极化域、变换域（频域、FRFT域、HHT域）和稀疏域的微动特征；2）采用极化特征分解、变换域（FRFT、短时FRFT、分数阶模糊函数、HHT及其改进方法）和参数模型技术（时变参数模型法和稀疏表示法）对微动特征进行增强、提取与参数估计；3）寻找能够反映海面目标存在的微动特征，利用差异微动特征形成检测统计量，实现恒虚警检测，同时采用实测海杂波数据进行验证与性能分析。

海杂波背景下稳健可靠的微弱动目标检测始终是雷达信号处理领域的一个难题。本项目将微多普勒理论引入对海雷达目标检测领域，突破仅利用目标质心平动引起的多普勒变化，而将目标微动产生的微多普勒看成干扰信号的传统目标检测方法的限制，系统研究海杂波和海面微动目标雷达回波模型和特性分析、微动信号匹配增强和特征提取技术以及海杂波背景中的检测器设计等一系列理论问题。充分利用时域、频域、分数阶傅里叶变换域（FRFT）、分形域、Hilbert-Huang变换域、稀疏域、极化域等回波信息区分海杂波和微动目标，改善信杂比，达到正确提取微动特征和提高雷达检测能力的目的。所提出的检测方法能够最大程度地利用目标回波信号的多普勒特征，扩展信号利用维度，提高检测性能。采用多波段、多极化、多种观测条件下雷达实测数据进行验证分析，相对于传统频域处理方法有重大改进。本项目的研究成果为进一步提高对低可观测海面目标的探测能力提供了技术支撑。. 本项目在IEEE期刊和IET会刊等国际期刊和本领域国际学术会议上发表学术论文46篇，其中SCI收录11篇，EI收录24篇。申报国家和国防发明专利11项（已授权8项）。培养博士（后）4名，硕士研究生3名。获山东省科学技术发明一等奖1项。