【作者】 刘春波；

【导师】 陈伯孝；

【作者基本信息】 西安电子科技大学 ， 信息与通信工程， 2008， 博士

【摘要】 高频地波雷达的探测距离可达300-400Km,可以填补天波超视距和常规微波雷达的监视盲区,在海洋遥感遥测方面具有实时性好、探测范围大和可全天候工作等优点。因此,高频地波雷达的研究对于临海国家对其“蓝色领土”及海上专属经济区(EEZ)实施有效管理和合理开发有着重要意义。本文研究一种新型的地波超视距雷达-岸-舰双基地高频地波SIAR,该雷达利用综合脉冲孔径雷达(SIAR)技术,将双基地与舰载体制进行结合,具有机动灵活、良好的抗定向有源干扰和抗反辐射导弹能力。论文针对信号波形设计与处理、发射阵列综合及超分辨处理、射频干扰抑制和海杂波特性分析及其抑制等方面进行了研究,主要工作概括如下:第1章介绍岸-舰双基地高频地波SIAR的研究背景及意义,回顾了高频地波雷达的研究与发展概况,并简要介绍了本文的主要研究内容。第2章介绍岸-舰双基地高频地波SIAR系统的基本工作原理。首先简单介绍岸-舰双基地高频地波SIAR的系统组成和工作特点,接着按照信号的处理流程,从发射同步信息提取、波形分析与综合处理、坐标变换与目标定位三个方面对该系统的工作原理进行了较为详细的阐述。最后对接收信号的组成及特点作了简单分析,并由此讨论了信号处理的主要任务。分析及实验结果表明,通过选择合适的信号波形参数,可以满足雷达的工作要求,实验数据的处理结果进一步验证了该新体制雷达的可行性。第3章研究发射阵列的综合设计及基于发射阵列的超分辨方法。根据发射系统的工作特点及要求,从系统方位分辨率、系统成本以及阵元互耦角度,分析以非均匀稀布MRL阵列作为发射阵形的工作性能。首先讨论了对应的发射信号频率编码的优化配置问题,研究了异频发射时的发射超分辨MUSIC算法,并分析了算法的目标分辨和参数估计性能;最后针对MUSIC算法受通道误差影响大的情况,研究了利用直达波信号的幅相误差自校准方法。分析表明,MRL阵列在系统成本、阵元相互影响、分辨性能以及对信噪比的要求等方面的表现都要优于均匀线阵;通过频率编码来实现发射信号正交,不仅可以提高系统的目标分辨性能,而且进一步提高了系统的测距精度。第4章研究单天线接收模式下的射频干扰抑制方法。首先分析该雷达多载频发射、单根全向天线接收时射频干扰在信号处理各环节的特征;由于射频干扰相对发射站没有“方向性”,因此利用干扰的时域、距离域及多普勒域特点,基于特征子空间正交投影思想,研究并提出了不同的时域、距离域干扰的抑制方法,并对所提方法的优缺点进行了分析比较。最后利用实测数据对所提方法的效果进行了验证。实测数据处理结果表明:在时域和距离域抑制射频干扰是可行和有效的。并且由于没有利用干扰的空域特征,因而其空间非平稳性并不会降低这些方法的性能,也不会影响目标的方向特性。第5章研究在接收平台运动条件下的海杂波特点。首先简单介绍了高频海杂波的产生机理,分析了接收平台静止及运动时海杂波多普勒谱的特点,推导了海杂波Bragg频率与系统几何参数的关系,分析了不同的接收平台运动状态下一阶海杂波谱的空时分布、时间调制特点及其对目标检测的影响;最后,在文献基础上,利用获得的海杂波统计特性对一阶海杂波进行了仿真和进一步的分析。分析表明,接收平台运动不仅导致海杂波多普勒频率与方位角产生耦合,而且还可能存在时间调制作用,导致一阶海杂波谱明显扩展,会大大降低海面低速目标的检测性能。第6章研究单根天线接收时空时耦合扩展海杂波的抑制方法。分别对利用Hankel降秩矩阵方法的空-时级联处理、利用线性约束(LCMV)的自适应波束形成方法的时-空级联处理和基于直接数据域(DDD)时空时二维联合处理(3DT-SAP和JDL)方法的海杂波抑制效果进行了分析和讨论,结合仿真数据,对上述算法进行了检验。研究表明:一个相干处理周期内,若接收平台近似做匀速直线运动,则通过时域方法和空时联合处理均可以有效抑制扩展的海杂波。第7章对全文的研究内容进行了总结,针对存在和尚未解决的问题,展望了未来研究工作的重点和方向。更多还原

【Abstract】 Owing to a low attenuation of vertically polarized HF radio wave on ocean surface, HFSWR is able to detect the targets of 300~400Km away. So it can be considered as complementary of HF sky wave radar and conventional microwave radar; and it also can be applied to the remote sensing of ocean state in real-time, large range and 24-hour working. Therefore, HFSWR plays important roles in the management and development of exclusive economic zones (EEZ) for oceanic countries.This paper studies a novel HFSWR—coast-ship bistatic high frequency surface wave SIAR (Synthetic Impulse and Aperture Radar). Using the SIAR technique, the radar successfully combines bistatic and shipborne operation. Thus the radar has the advantages of flexibility and the ability of rejecting directional active jamming and ARM (Anti-Radiation Missile). The researches of the paper are outlined as follow:Chapter 1 introduces the background and necessary of coast-ship bistatic high frequency surface wave SIAR. The history of HFSWR and some typical systems are firstly reviewed. The contents of the paper are also presented.Chapter 2 introduces operation principles of the novel radar. According to the signal processing flow, the system configuration and framework are firstly presented, and then the operation principle is introduced detailedly by introducing the system synchronization, the parameters selection and synthesis processing of LFMICW, and coordinate transform and location; finally, some key techniques in signal processing are discussed in brief.The demands of the radar on signal waveform can be met by selecting the parameters, and the experimental results show the feasibility of the radar.Chapter 3 studies the configuration of transmit array and range-angle joint superresolution processing based on transmit array. The operation performance of Minimum Redundancy Linear array (MRL) as transmit array is investigated in resolution, estimation precision with MUSIC algorithm. The frequency code is selected for releasing the coupling between range and angle with GA (Genetic Algorithm). The calibration of channel errors of gain and phase is proposed using the direct wave from the transmit site.The analyses show that MRL has advantages over ULA or plane array in system cost, element coupling and resolution; the orthogonal waveform with frequency code is better than that with the phase code of the same frequency for the improvement of system resolution and range precision.Chapter 4 studies the suppression of radio frequency interference (RFI) when only a single omnidirectional antenna is utilized. The features of RFI in time, range and Doppler domain are analyzed firstly; and then the orthogonal projection algorithm is utilized to mitigating the time and range domain RFI. The new methods for estimating the covariance matrix is propose based on the features of RFI. The algorithm is examined with the practical data.The experimental results prove that the proposed method can effectively suppress the RFI without the distortion of target pattern even when the RFI is spatially nonstationary.Chapter 5 investigates the characteristics of sea clutter with a single antenna on a moving receiver platform. Based on the mechanism of first-order sea clutter, the Doppler frequency of sea clutter is formulated about the system geometry. The space-Doppler coupling and time-modulating of sea clutter are discussed.The spectrum of sea clutter will be widen when the receiver is moving, which directly lead to the difficulty in detecting such slow targets as ships or boats.Chapter 6 studies how to suppress the spreading sea clutter. The Hankel rank-reduced matrix method based on singular value decomposition (SVD) is applied in beam space; and spatial adaptive filtering with Doppler pre-processing is also tested; finally, two space-time adaptive processing algorithms: mDT-SAP and JDL (Joint Domain Localized) with Direct Data Domain (DDD) method are tried to suppress the clutter. The simulation results show the validity of the above methods.Chapter 7 makes conclusions about the study of the paper, and some problems to be solved and future working are presented in the end.更多还原