卫星导航信号联合处理技术研究

发布时间：2018-01-12 01:30

本文关键词：卫星导航信号联合处理技术研究　出处：《国防科学技术大学》2014年博士论文　论文类型：学位论文

【摘要】：随着卫星导航芯片在电子设备中的广泛应用和全球卫星导航系统的蓬勃发展,卫星导航定位在城市峡谷、室内和密林等弱信号环境下的应用需求不断增加,研发具有高灵敏度和高可靠性接收机的任务更加迫切。本文以利用冗余卫星和辅助信息实现性能提升为背景,在联合捕获、矢量跟踪、抗差定位以及完好性监测等方面进行了探索和研究。(1)与传统捕获分别对单个卫星信号进行时间和频率的二维搜索方法不同,联合捕获在接收机概略位置、速度和时间(PVT,Position Velocity and Time)等初值附近进行搜索,充分利用卫星信号间相关性和星历等辅助信息,提高捕获灵敏度。针对当前联合捕获缺少理论分析的问题,详细推导了联合捕获的广义似然比检测量及其虚警概率和检测概率的解析式,定量分析了时延和多普勒估计误差引起的检测损耗,为捕获门限确定和参数优化提供理论依据。针对联合捕获检测量计算复杂的问题,提出了一种简化实现结构和选星算法。仿真结果表明:联合捕获灵敏度随着可见卫星数增多而提高;在12颗卫星可见和相干积分时间为1ms的相同条件下,简化后的联合捕获比传统单星捕获灵敏度提高了7.5d B左右。(2)针对当前播发的卫星导航信号普遍存在电文调制情况,提出了一种基于改进差分相干的联合捕获算法以及相应统计量的概率密度函数解析式,有效地解决了电文比特翻转导致的捕获统计量峰值与PVT真值不对应的问题,为相干积分时间和差分相干后积累次数的最优参数设计提供理论基础。提出了一种基于统计量概率密度函数解析式的优化参数方法,解决了数值仿真法在参数优化设计中存在的精度和计算量难以平衡问题。此外,通过搭建GPS(Global Positioning System)模拟射频信号采集和处理的实验平台,验证了改进差分相干的联合捕获算法抑制比特翻转的有效性。(3)围绕矢量延迟锁定环的跟踪精度和有偏性问题展开。首先,针对收敛速度和跟踪精度难以平衡的问题,提出了一种环路带宽自适应调节的矢量延迟锁定环改进算法。其次,针对可见卫星大于4颗时收敛点不唯一而出现的跟踪有偏问题,提出了基于奇偶空间投影的偏差检测和修正算法,该改进算法包含两种不同的实现结构:一是在传统矢量延迟锁定环结构上通过增加码相位残差投影变量检测实现跟踪偏差监测,二是对位置域在奇偶空间的投影矢量进行自适应变维跟踪。相同仿真场景的数据处理结果表明:在特定的条件下,传统的矢量跟踪算法最大码跟踪偏差为16.706m,改进后最大仅为1m,实现了近似无偏的跟踪;基于变维跟踪的实现结构由于采用了环路带宽自适应调节算法,在收敛速度和跟踪精度的平衡上优于残差监测的实现结构,但实现结构更加复杂。(4)针对传统定位算法和接收机自主完好性监测(RAIM,Receiver Autonomous Integrity Monitoring)算法无法有效抑制多个伪距粗差的问题,提出了基于M-估计的抗差定位算法和相应的抗差自主完好性监测算法,该抗差自主完好性监测算法采用改进的保护级别来评估最坏情况下抗差定位误差。结合具体GPS观测数据的实验结果表明:在12颗卫星可见情况下,所提出的抗差定位算法有效抑制3颗卫星信号中的粗差;抗差自主完好性监测算法的水平保护级别约为传统RAIM的50%,垂向保护级别约为传统的33%,能够满足更加严格的保护级别要求。最后,对论文的研究成果及工程应用进行了总结,并对下一步将要开展的工作进行了展望。论文的部分研究成果已应用于高性能接收机和多体制信号模拟源等项目的设计论证、开发与测试中。
[Abstract]:With the rapid development of satellite navigation chip in electronic equipment and application of global satellite navigation system, satellite navigation and positioning in the city canyons, forests and other indoor applications in weak signal environment is increasing, development with high sensitivity and high reliability of the receiver task more urgent. In order to achieve performance improvement as the background using redundant satellite and the auxiliary information, tracking vector in the joint acquisition, and has carried on the exploration and study of robust positioning and integrity monitoring etc. (1) with the traditional two-dimensional capture time and frequency respectively for single satellite signals in different search methods, combined capture receiver outline position, velocity and time (PVT, Position Velocity and Time the initial search nearby) etc., make full use of the satellite signal correlation and ephemeris auxiliary information to improve the acquisition sensitivity. In view of the current joint acquisition Lack of theoretical analysis. Detailed derivation of the generalized likelihood ratio test and the analytical formula of detection probability and false alarm probability and capture, quantitative analysis of the time delay and Doppler estimation of detection error caused by the loss, to determine the capture threshold to provide a theoretical basis and parameter optimization. For the joint acquisition of measuring the computational complexity of the problem, put forward to achieve a simplified structure and satellite selection algorithm. Simulation results show that the joint acquisition sensitivity increases with the increase in the number of visible satellites; 12 satellites visible and coherent integration time is 1ms under the same conditions, Jane after joint acquisition than the traditional single star acquisition sensitivity increased 7.5d B. (2) according to the satellite the navigation signal broadcast universal message modulation, we propose a joint acquisition algorithm and the corresponding statistics of the probability density function based on improved differential coherent analysis Type, effectively solve the message bit flip to capture statistics peak value and the true value of PVT should be no problem, and provide a theoretical basis for optimal parameter design for the number of accumulated time coherent integration and differential coherent. After put forward a method of optimizing parameter statistic probability density function analytic formula based on the numerical simulation method to solve parameter optimization of accuracy and computational design are difficult to balance. In addition, by setting up the GPS (Global Positioning System) simulation platform of RF signal acquisition and processing, to verify the validity of the modified differential joint acquisition algorithm to suppress the bit flipping coherent. (3) the vector delay lock loop tracking accuracy and partial problems. Firstly, the convergence speed and tracking accuracy is difficult to balance problems, put forward a kind of vector control loop bandwidth adaptive delay locked loop is improved Method. Secondly, according to the visible satellite more than 4 stars not only caused the convergence point tracking bias problem, put forward the deviation parity space projection detection and correction algorithm based on the improved algorithm includes the realization of two different structures: one is the delay locked loop structure by increasing the code phase tracking variable detection of residual projection the deviation in the traditional vector monitoring, two is adaptive target tracking on the projection vector in the space domain. The parity data processing results of the same simulation scene show that under certain conditions, the traditional vector tracking algorithm the code tracking error is 16.706m, the improved maximum of only 1m, the approximate unbiased tracking; variable dimension tracking structure due to the loop bandwidth adaptive adjustment algorithm based on structure is better than that of residual monitoring in convergence speed and tracking accuracy of the balance, but the realization of node The structure is more complex. (4) the traditional location algorithm and the receiver autonomous integrity monitoring (RAIM, Receiver Autonomous Integrity Monitoring) algorithm can not effectively suppress multiple pseudo error problem, proposed M- estimation robust positioning algorithm and the corresponding robust autonomous integrity monitoring algorithm based on the robust independent intact monitoring algorithm using improved protection level to evaluate the worst-case robust positioning error. Combined with the specific GPS data. The results showed that in the 12 satellite visible case, the proposed robust positioning algorithm can effectively suppress outliers 3 satellite signal; robust autonomous integrity monitoring algorithm level the level of protection is about 50% of the traditional RAIM, the vertical protection level is about the traditional 33%, the level of protection can meet the more stringent requirements. Finally, the research results and engineering application of thesis are summarized, and the The future work will be prospected. Part of the research results have been applied to the design, demonstration, development and testing of high performance receivers and multi system signal simulation sources.

【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】：TN967.1

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