【作者】 张冰；

【导师】 田斌；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2018， 硕士

【摘要】 本文重点研究了基于自适应调零天线的卫星导航接收机的抗干扰技术,从常规接收机的干扰容限入手,探索了自适应空间陷波技术和波束成形技术能够提升接收机干扰容限的最大程度;从两个角度分析了卫星导航接收机的抗干扰能力:一个是对抗人为干扰的能力,另一个是对抗恶劣环境(如低信噪比环境)的能力。针对人为干扰,本文分析了兼有自适应空间陷波与波束成形天线阵列的卫星导航接收机的抗干扰能力,指出该方法存在的不足,并提出一种改进设计方案;针对低信噪比环境,本文分析了常规接收机的干扰容限,指出了存在的问题,并提出了改进算法提升了接收机的捕获和跟踪性能。本文的主要研究成果如下:1.对卫星导航接收机的抗干扰性能及其仿真测试方法进行了研究。讨论了GPS系统的干扰容限,给出了其定义和计算方法,总结了目前提升卫星导航接收机抗干扰能力的一些常用措施,重点分析了自适应调零天线对抗敌方恶意干扰的能力,设计了一种仿真测试方法用于对卫星导航接收机的抗干扰能力进行研究,该方法可以最大化模拟真实接收机的结构,为后续接收机抗干扰能力测试的结果提供了可靠的依据。为了准确地描述接收机在干扰条件下的工作状态,本文给出三种干扰起效判决准则,并计算了GPS C/A码接收机和P(Y)码接收机在这三个准则下的干扰容限。给出了兼有自适应空间陷波与波束成形阵列天线系统的抗干扰测试结果,分析了该方法的优势与不足。2.对兼有自适应空间陷波与波束成形阵列天线系统的一些关键技术进行了研究。设计了一种用于GPS军用码信号和民用码信号的滤波器组,采用了分级滤波下采样的结构,详细分析了该滤波器组的性能,并且与常规滤波器进行了对比,结果表明该滤波器组在保证性能的同时降低了资源占用,而且还降低了信号处理的延迟,从而减小了对后续信号处理的影响。针对低信噪比环境,提出了一种半比特PMF-FFT捕获方法,提升了GPS C/A码接收机的捕获灵敏度,并改进了接收机的跟踪环路,提出两种新型鉴相器算法,性能仿真结果表明,这两种算法都可以获得较好的载波同步性能。针对常规的波束成形技术存在的一些问题,本文提出一种无需导向矢量辅助的自适应波束成形方法,结果表明,该方法同样可以获得阵列天线的空间分集增益,提升信噪比。3.完成了一个自适应调零天线工程样机中的一些基带信号处理单元的FPGA设计实现。基带信号处理单元包括滤波器模块、民用码同步捕获模块、民用码的码同步和载波同步模块、自适应空间陷波模块和自适应波束成形模块,各模块均与MATLAB仿真结果进行了对比验证。更多还原

【Abstract】 This thesis focuses on the research of anti-jamming techniques of satelite navigation receiver with adaptive nul ing antenna.We start from the interference tolerance of the general receiver,and then we explore the maximum interference tolerance that adaptive spatial notch and beamforming can improve.We analyze the anti-jamming capability of GNSS receiver from two angles.One is the ability to restrain factitious jamming,the other one is the ability to against the harsh environment(such as low SNR environment).In terms of factitious jamming,this thesis analyzes the anti-jamming capability of the satellite navigation receiver with adaptive spatial notch and beamforming antenna array,points out the disadvantages of this method,and proposes an improved design scheme.As for low SNR environment,this thesis analyzes the interference tolerance of the general receiver,points out the existing problems,and proposes the improved algorithm which can improve the capture and tracking performance of the receiver.The main research results of this thesis are as follows:1.The anti-jamming performance of satellite navigation receiver and its simulation test method are investigated.The definition of interference tolerance of GPS receiver is given,and some commonly used measures to improve the anti-jamming capability of satellite navigation receiver are summarized,and the ability of adaptive nul ing antenna to counteract enemy malicious interference is analyzed emphatically.A simulation test method for the antijamming capability of satelite navigation receiver is designed,which can imitate the structure of the real receiver.In order to accurately describe the working state of the receiver under the interference condition,three kinds of interference effect decision criterias are given in this thesis.The interference tolerance of GPS C/A code receiver and P(Y)code receiver under these three criteria is calculated.The anti-jamming test results of both adaptive spatial notch and beamforming array antenna system are given,and the advantages and disadvantages of this method are analyzed.2.Some key techniques of both adaptive spatial notch and beamforming array antenna systems are studied.A filter bank for GPS military code signal and civil code signal is designed.The structure of hierarchical filter down-sampling is adopted.The performance of the filter bank is analyzed in detail and compared with the conventional filter.The results show that the filter bank can reduce the resource consumption while ensuring the performance,and the low delay of signal processing reduces the influence on the subsequent signal processing.A half-bit PMF-FFT acquisition method is proposed for low SNR environment.The acquisition sensitivity of the GPS C/A code receiver is improved,and the tracking loop of the receiver is improved.Two novel phase discriminator algorithms are proposed.The performance simulation results show that both of these algorithms can achieve better carrier synchronization performance.Aiming at some problems in the existing beamforming techniques,an adaptive beamforming method without guidance vector assistance is proposed in this thesis.The results show that,this method can also obtain the spatial diversity gain of array antenna and improve the signal-to-noise ratio(SNR).3.The FPGA design and implementation of some baseband signal processing units in an adaptive nul ing antenna engineering prototype are given.The baseband signal processing units contain high performance filter module,civil code synchronization acquisition module,civil code synchronization and carrier synchronization module,adaptive spatial notch module and adaptive beamforming module,and these modules are compared with the simulation results of MATLAB.更多还原