【作者】 李延辉；

【导师】 王宏远；

【作者基本信息】 华中科技大学 ， 通信与信息系统， 2005， 硕士

【摘要】 在导航战中,GPS已经成为精确指挥控制、精确打击和精确兵力投送的关键,并且在战争的各个阶段影响着战争的方式和效能。干扰GPS不但可以破坏隐身飞机、巡航导弹和其它作战飞机、军舰、坦克的准确攻击,而且还能破坏它们之间的作战协同,因此研究GPS的干扰理论与技术已成为我军当务之急。本文主要研究压制干扰条件下GPS接收机的捕获与跟踪性能。在对GPS直接序列扩频通信体制进行分析后得出:GPS C/A码接收机和P码接收机分别达到了43dB和53dB的扩频增益,因此具有一定的抗干扰能力。从GPS接收机捕获和跟踪电路出发,详细推导了信号捕获与跟踪的数学模型。在给出捕获状态下检测概率和虚警概率的表达式基础上,求出了平均捕获时间与捕获时间方差; 同时得到了跟踪状态下定时误差的方差。针对以上结果,对其用MATLAB仿真工具进行了压制干扰状态下的仿真。结果表明:一方面,点频干扰比窄带干扰效果更好,而窄带干扰的效果比宽带干扰效果好; 另一方面,尽管GPS接收机具有一定的抗干扰能力,但干扰功率达到一定值时,GPS接收机并不能正常捕获和跟踪信号。本文为压制干扰下GPS接收机的干扰效果评估和干扰样式的选择提供了理论依据。更多还原

【Abstract】 In the war of navigation, usage of the GPS has become essential for precise command control and the precision of attacks and armed force deployment and influence the means and effects of the war at its every phase. Interference on the GPS can not only disrupt the precision of attacks by stealth planes, cruise missiles and other warplanes, warships, and tanks, but also the coordination among them during the war. So reasearch on the theory and technology of the GPS interference has become the urgent task for the Chinese army. This paper focused on analyzing the GPS receiver’s acquisition and tracking performance under suppressing interference. After analysis on the GPS communication system’s property of direct sequence spread spectrum, this paper conclude: the GPS’ C/A code receiver and P code receiver have a spread spectrum gain of 43dB and 53dB. So they have the anti-interference ability to a certain degree. This paper deduced a detailed mathematical model for signal acquisition and tracking based on the analysis of the GPS receivers’ circuit. After deducing the expression formula for the probability of signal detection and false alarm under the acquisition state, this paper calculated the average accquistion time and its variance; and also calculated the timing error variance under the tracking state. Based on the above results, this paper performed the simulation using Matlab tools under the suppressing interference. The results indicate that: firstly, single frequency interference has a better interference effect than narrowband interference, and narrowband interference has a better effect than broadband interference; secondly, despite the fact that the GPS receiver has certain anti-interference capability, when the interference power reaches certain level, the GPS receiver can not acquire and tracking the signal normally. The results provide the theoretical basis for analyzing the effect of suppressing interference of the GPS receiver and the evaluation of choices of interference mode.更多还原