天发舰收高频雷达展宽海杂波的抑制和目标检测技术研究

Based on the propagation mode associated with sky and surface wave, the HF hybrid sky-surface wave radar not only maintains the superiority of HF skywave radar which have a long detection rang and wide coverage, the advantage of HF surface radar which have a stable propagation channel, but also keeps a good invisibility and anti-interference ability. Novel HF hybrid sky-shipborne radar appears to be more agile, which could effectively improve the early-warning ability of ship targets. However, the sea clutter under this combined propagation mode is influenced by a number of composite factors such as the bistatic angle, ionospheric distortion and platform movement, etc. Therefore, the width and shape of Doppler spectrum will be broaden and complicated, giving rise to the severely restriction of ship target detection. This project intends to study the internal mechanism and characteristics of the spread sea clutter deeply and carefully, so as to construct the model which can describe the spread sea clutter. Afterwards, based on the preceding research, the technique to suppress the spread sea clutter utilize a spatial-temporal cascaded processing could be obtained to compensate the effect of ionospheric perturbation and platform movement. Eventually, the target detection method, under the background of HF hybrid sky-shipborne spread sea clutter, will finally be proposed according to the stationary difference between the clutter and target. To sum up, the research in this project is deemed to have important academic value and engineering significance, and will provide the theory and technology foundation to detect the target over the horizon under the spread sea clutter in HF hybrid sky-shipborne radar.

基于天波发射-地波接收组合传播模式下的高频雷达兼具天波传播距离远、覆盖范围大以及地波绕海面传播稳定的双重优点，并且具有双基地雷达固有的隐蔽性和抗干扰能力。天波发射-舰载接收系统进一步提高了高频雷达的机动性和对舰船的早期预警能力，然而天发-舰收组合传播模式下的海杂波受双基地角、电离层扰动以及平台运动等多种因素的复合影响，海杂波展宽范围大且形态复杂，严重制约了舰船目标的检测。本项目通过深入分析天发-舰收海杂波展宽的内在机理和特性，建立海杂波展宽模型；在此基础上分别对电离层引起的时域调制和平台运动引起的空间动态耦合的补偿方法进行研究，进而提出基于空间和时间联合处理的海杂波展宽抑制方法，最后根据杂波与目标时域非平稳性特征的差异，提出一种天发-舰收展宽杂波背景下的目标检测方法。本项目的研究可为天发-舰收高频雷达实现展宽海杂波下的目标检测奠定理论和技术基础，具有十分重要的理论研究价值和工程意义

天波发射-舰载接收组合传播模式下的高频雷达兼具天波探测距离远、地波传播稳定以及舰载平台机动灵活的优点，对提高海上舰船早期预警能力以及海态遥感等海洋科学研究具有重要价值。该项目针对天发舰收高频雷达复杂展宽海杂波背景下船目标检测难题，从海杂波特性与展宽模型、电离层扰动引起海杂波展宽的补偿方法、展宽海杂波背景下的杂波抑制与目标检测方法三个方面开展研究，解决了目标检测的关键理论与技术难题。.在展宽海杂波特性及模型研究方面，首次揭示了电离层扰动、双基地布局以及舰载平台运动对天发舰收高频雷达海杂波回波信号的影响机理，创新发展了海杂波散射截面积公式等理论，定量阐述了多因素复合作用的影响，首次建立了多物理因素复合作用下的天发舰收高频雷达海杂波多普勒谱模型和空时二维谱模型。为拓展混合体制高频雷达领域、深入研究天发-舰收信号处理方法以及工程实现奠定了理论基础。.在电离层扰动引起海杂波展宽补偿方法研究方面，针对电离层空时扰动导致的信号波前畸变与非线性相位扰动影响，提出了三种有效的电离层补偿算法。其中首次提出了针对平台运动情况下动态耦合的电离层非线性相位扰动的补偿方法。实测数据和半实物仿真数据验证表明，补偿后海杂波谱展宽得到明显改善。.在展宽海杂波背景下杂波抑制与目标检测方法研究方面，首先，系统地分析了混合体制高频雷达海杂波距离域特性、空域特性、自由度、稀疏性、非平稳性等多种特性。其次，针对该体制雷达杂波抑制与目标检测研究中样本极度缺乏以及杂波环境严重非平稳的难题，依据不同海杂波特性有针对性地提出了多种小样本条件下非平稳展宽海杂波抑制方法和非平稳背景下的广义似然比目标检测方法。实测数据和半实物仿真数据验证表明，较传统海杂波抑制与目标检测方法，所提方法对目标信杂比改善明显，有效提高了天发舰收高频雷达目标检测能力。