北斗导航接收机的抗干扰算法研究

发布时间：2018-03-30 21:18

本文选题：北斗导航系统　切入点：抗干扰　出处：《西安电子科技大学》2014年硕士论文

【摘要】：北斗卫星导航系统是我国的第二代卫星导航系统,系统建成后将为其用户在全球范围内提供全天候的位置、导航以及时间信息。然而面对日益复杂的电磁环境,卫星导航系统很容易受到各种无意或者人为的干扰,使得地面导航接收机有时可能无法正常工作,因此有必要提高北斗导航系统接收机在干扰环境下的工作能力。本文以北斗二代导航系统为研究对象,在时域、空域以及空时联合域上研究了抗干扰算法。在时域内研究了一种基于全通滤波器的自适应陷波器,该陷波器利用改进的高斯牛顿算法在每步的迭代过程中计算出最优收敛因子,仿真结果表明该算法具有更快的收敛速度和更佳的干扰抑制效果。在空域上,研究了功率倒置算法,通过仿真分析了阵元数,输入信干比和干扰信号方向对算法性能的影响。假设天线有M个阵元,则天线阵列的自由度为M?1,即最多能够抑制M?1个干扰,当干扰数较多时,需要增加天线阵元数,这无疑会增加系统的体积和成本,且功率倒置算法不具有频率的分辨力。针对以上缺点研究了空时二维联合抗干扰算法,通过在每个阵元后添加若干个延时单元,在空域和时域内对信号进行处理,大大的提高了算法的自由度,且使得算法在频域内同样具备分辨力。通过仿真分析了阵元数、抽头延迟数、干扰数、输入信干比和干扰信号方向对空时二维抗干扰算法性能的影响。传统的抗干扰方法只是单纯的对干扰信号进行了零陷,并没有利用导航信号的特点,且传统的抗干扰方法对导航信号有一定的衰减,在导航信号到达地面本身能量已经相当微弱的情况下,有可能影响接收机后续的捕获与跟踪,因此在本文的最后一部分,研究了基于互相关系数的谱自相干恢复(Cross Spectral Self-coherence Score,简称Cross-SCORE)抗干扰算法,该算法利用北斗信号中测距码的周期重复性,在干扰信号不具备周期平稳特性的情况下,通过调整阵列的加权矢量使接收信号与参考信号的互相关系数达到最大,从而达到增益导航信号抑制干扰信号的目的。该算法具有在没有任何先验知识条件下对导航信号产生增益的优点,但该算法需要进行特征值分解运算,计算量巨大,因此本文提出了自适应Cross-SCORE算法,大大减少了运算量,并通过仿真分析了算法的性能。
[Abstract]:Beidou satellite navigation system is the second generation of satellite navigation system in China. When the system is completed, it will provide its users with all-weather position, navigation and time information on a global scale.However, in the face of increasingly complex electromagnetic environment, satellite navigation systems are vulnerable to all kinds of unintentional or man-made interference, and sometimes the ground navigation receivers may not work properly.Therefore, it is necessary to improve the performance of the Beidou navigation system receiver in the interference environment.In this paper, the Beidou second generation navigation system is taken as the research object, and the anti-jamming algorithm is studied in time domain, spatial domain and space-time joint domain.An adaptive notch filter based on all-pass filter is studied in time domain. The improved Gao Si Newton algorithm is used to calculate the optimal convergence factor in the iterative process of each step.Simulation results show that the algorithm has faster convergence speed and better interference suppression effect.In spatial domain, the power inversion algorithm is studied. The effects of array number, input signal-to-interference ratio and interference signal direction on the performance of the algorithm are analyzed by simulation.Assuming that there are M elements in the antenna, the degree of freedom of the antenna array is M1, that is to say, the maximum number of interference can be suppressed. When the number of interference is large, the number of antenna array elements should be increased, which will undoubtedly increase the volume and cost of the system.And the power inversion algorithm has no frequency resolution.In view of the above shortcomings, the space-time two-dimensional joint anti-jamming algorithm is studied. By adding several delay elements after each array element, the signal is processed in the space and time domain, which greatly improves the degree of freedom of the algorithm.The algorithm also has resolution in frequency domain.The effects of array number, tap delay number, interference number, input signal-to-interference ratio and interference signal direction on the performance of space-time two-dimensional anti-jamming algorithm are analyzed by simulation.The traditional anti-jamming method is simply zero trapping of the interference signal, and does not make use of the characteristics of the navigation signal, and the traditional anti-jamming method has a certain attenuation to the navigation signal.When the navigation signal reaches the ground itself, the energy is quite weak, which may affect the subsequent acquisition and tracking of the receiver, so in the last part of this paper,In this paper, a spectral autocoherent recovery Spectral Self-coherence Score-based anti-jamming algorithm is studied. The algorithm makes use of the periodic repeatability of the ranging code in Beidou signal, and the interference signal does not have the characteristic of periodic stationarity.By adjusting the weighted vector of the array, the number of interrelation between the received signal and the reference signal is maximized, so that the gain navigation signal can suppress the interference signal.This algorithm has the advantage of generating gain to navigation signal without any prior knowledge. However, the algorithm needs eigenvalue decomposition operation and the computation is huge. Therefore, an adaptive Cross-SCORE algorithm is proposed in this paper, which greatly reduces the computation cost.The performance of the algorithm is analyzed by simulation.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN965.5

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