GPS接收机抗干扰研究

发布时间：2018-05-14 07:34

本文选题：全球定位系统(GPS) + 多级维纳滤波(MWF)　；参考：《国防科学技术大学》2014年博士论文

【摘要】：导航系统正用于战场各种武器平台及飞行器,但容易受到干扰。因此导航信号抗干扰当前受到严重关注,是在理论、实现算法及技术等方面需要深入研究的课题。本文结合两个科研项目:一、航天部某研究所的委托的“GPS/GLONASS/北斗I三模抗干扰中频模块设计”;二、通信抗干扰技术国家级重点实验室基金项目“空时频多维DOA估计与方向约束抗干扰滤波技术研究”。这两个课题都与全球定位系统(GPS:Globe Positioning System)抗干扰技术密切相关。空时自适应处理(STAP:Space-Time Adaptive Processing)有较大的抗干扰自由度,是应对干扰环境的一种有效方法。为避开矩阵特征分解,可采用正交投影方法实现STAP。正交投影类算法都存在一个问题,即存在一个最佳的投影次数,超过之后会使信干噪比下降,这在实际中更明显。针对这一问题,提出两种解决方法。一、将对角加载引入典型的正交投影算法多级维纳滤波中,提高了算法的鲁棒性,使其在实际环境中获得稳定的抗干扰性能。二、运用多级维纳滤波器对观测数据矢量进行分析,估计出最佳投影次数,从而获得最优抗干扰效果。为使导航信号平台在多干扰环境下仍能正常工作,需在阵元数有限情况下,发挥现有接收天线的最大效能。对此采用级联方法处理,在复杂信号接收环境下检测并消除窄带干扰,然后用自适应阵消除其余干扰。在接收信号中含有多种干扰时,频谱较为复杂,难以采用一般处理窄带干扰的方法。为解决这一问题,采用了一种滑窗式的频谱处理法,可以在较复杂的频谱中有效检测出单频和窄带干扰。在空域处理中,提出一种成对变换的Jacobi迭代运算方法,可削减协方差矩阵特征分解的运算量。战场环境下,非平稳干扰以及载体高速运动对抗干扰性能影响较大,有必要研究有效解决方法。线性扫频(LFM:Linear Frequency Modulation)干扰是典型的非平稳干扰。可按如下方式处理:通过时频分析提取干扰信号参数,据此构建干扰子空间,用子空间投影的方法即可消除干扰。本文提出一种LFM干扰参数估计方法,相对于传统的Weigner-Hough变换,可以极大的减小运算量。文中分析了子空间投影处理中参数估计误差对于抗干扰性能的影响,给出相应解决方法。一般性非平稳干扰可用自适应阵对消,文中4.2节研究了该类干扰的波达方向估计,但将处理过程放在4.3节与平稳干扰一起讨论。这是因为,如用自适应阵处理,非平稳和平稳干扰可采用同样的处理方式。因此没必要在第4.2节单独讨论非平稳信号的对消。在时频分布的优化处理中,推导出自源点与互源点对应矩阵的迹的表达式,根据表达式可以清楚选出自源点。由于载体高速运动以及自身高频振动,干扰入射角在处理时段内有变动,可能使抗干扰性能下降很大,因此有必要研究应对方法。可分干扰方向已知和未知两种情况讨论。当干扰方向已知时,可用传统方法解决上述问题。对于干扰方向未知的情况,本文提出一种方法,在最优化表述中使用适合于实际情况的约束条件,据此推导出具备零陷扩展功能的自适应权值,可以有效应对载体动态带来的干扰入射角偏移。在GPS抗干扰的理论研究和系统设计中存在一个突出问题:仿真条件随意设置,没有反映真实信号接收环境。为解决这一问题,分别在仿真和设计环境中模拟了阵列天线上接收到的GPS信号,产生了贴近于真实的仿真和测试平台。之后在同一章描述了抗干扰系统的设计,可以用于三种导航信号的抗干扰。借助模拟产生的接收信号对抗干扰系统进行测试,可以更方便地改进设计。设计完成后进行了实测,过程测试和最终的定位结果检验了所设计的系统。
[Abstract]:Navigation system is used on the battlefield weapons platform and aircraft, but susceptible to interference. So the navigation signal interference current is a serious concern, in theory, algorithm and technology aspects need further research topic. This article combines two research projects: first, a Research Institute commissioned by the Department of space "GPS/GLONASS/ Beidou I three die The design of anti-jamming medium frequency module "; two, the National Key Laboratory of Communication Anti-jamming Technology, the research on space-time multidimensional DOA estimation and directional constraint anti-jamming filtering technology". These two topics are closely related to the global positioning system (GPS:Globe Positioning System) anti-jamming technique. Space time adaptive processing (STAP:Space-Time Adaptive Processing is an effective method to deal with the interference environment. In order to avoid the matrix characteristic decomposition, there is a problem that the orthogonal projection method can be used to realize the STAP. orthogonal projection algorithm, that is, there is a best number of projection, which will reduce the signal to noise ratio after over, which is more obvious in practice. In order to solve this problem, two solutions are proposed. First, the diagonal loading is introduced into the typical orthogonal projection algorithm multilevel Wiener filtering to improve the robustness of the algorithm and make it obtain stable anti-interference performance in the actual environment. Two, the observation data vector is analyzed with multistage Wiener filter, and the best projection times are estimated. In order to get the best anti-interference effect, in order to make the navigation signal platform working in the multi interference environment, it is necessary to play the maximum efficiency of the existing receiving antenna under the limited array element number. The cascade method is used to detect and eliminate the narrow band interference in the complex signal receiving environment, and then the rest interference is eliminated by the adaptive array. In order to solve this problem, a sliding form spectrum processing method is adopted to effectively detect single frequency and narrow band interference in more complex spectrum. In the space processing, a kind of Jacobi iterative transport is proposed. The calculation method can reduce the computation of the eigendecomposition of covariance matrix. Under the battlefield environment, the non stationary interference and the high speed motion of the carrier have great influence on the interference performance. It is necessary to study the effective solution. The LFM:Linear Frequency Modulation interference is a typical non-stationary interference. The interference signal parameters are extracted and the interference subspace is constructed, and the interference can be eliminated by subspace projection. A LFM interference parameter estimation method is proposed in this paper. Compared with the traditional Weigner-Hough transform, the calculation amount can be greatly reduced. The parameter estimation error in subspace projection processing is analyzed for the anti-interference performance. The general non-stationary interference can be eliminated by adaptive array. The 4.2 section of the paper studies the direction of arrival of this kind of interference, but the processing is discussed in the 4.3 section with stationary interference. This is because, for example, the same processing method can be used for non stationary and stationary interference with adaptive array processing. Therefore, it is not necessary. In Section 4.2, we should discuss the cancellation of non-stationary signal separately. In the optimization of the time frequency distribution, the expression of the trace of the corresponding matrix between the source and the mutual source point is derived, and the self source point can be clearly selected according to the expression. The interference angle is changed during the processing period because of the high speed motion of the carrier and the high frequency vibration of the self. There is a great decrease in disturbance performance. Therefore, it is necessary to study the coping methods. Two cases with known and unknown interference directions are discussed. When the interference direction is known, the traditional method can be used to solve the above problems. For the unknown interference direction, a method is proposed in this paper to use the constraints suitable for the actual situation in the optimization expression. An adaptive weight with zero sink extension function is derived, which can effectively cope with the interference incident angle offset caused by the carrier dynamic. There is a prominent problem in the theoretical research and system design of GPS anti-jamming: the simulation conditions are set at will, and the real signal receiving environment is not reflected. In order to solve this problem, the simulation and design ring are solved respectively. In the environment, the GPS signals received on the array antenna are simulated, and the simulation and testing platform which is close to the reality is produced. After that, the design of the anti-jamming system is described in the same chapter, which can be used for the anti-interference of the three kinds of navigation signals. After the completion of the measurement, the process test and the final positioning result verify the designed system.

【学位授予单位】：国防科学技术大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P228.4

【相似文献】