【作者】 张玮；

【导师】 席晓莉；

【作者基本信息】 西安理工大学 ， 通信与信息系统， 2008， 硕士

【摘要】 全球定位系统(GPS)是精密卫星导航定位系统,它具有高精度、全天候、全球覆盖等优点,在军用及民用领域得到了广泛的重视和应用。由于直接面向用户,GPS接收机近年来更是发展迅速,新产品不断出现,产品更新换代加快。在GPS接收机中,稳定地跟踪卫星信号是系统正常工作的前提,一直是接收机技术中研究的重点。在高动态环境下,由于载体的高速运动使GPS接收机接收到的卫星信号附加了多谱勒频移,而且这种频移可能会伴有一定的加速度和加加速度,从而带来了载波频率和伪随机码时延的实时性改变,解决这一问题的关键在于使接收机更好地完成本地伪码和载波对信号伪码和载波的同步跟踪。本文首先分析了空间GPS信号的构成形式,然后从锁相环的角度出发,较详细地分析了GPS接收机中几种常用的载波环鉴频器和鉴相器、码环鉴相器,环路滤波器,在仿真的基础上对各种算法进行比对,介绍了数字压控振荡器的工作原理与设计方法。对环路测最误差的产生原因进行了分析,在此基础上给出了选择环路跟踪门限和环路带宽的一般方法。最后在锁频辅助锁相的思路指导下,给出了两种适应高动态环境的跟踪环路方案,通过仿真分析证实方案在高动态环境下的有效性和合理性,解决了载体在伴有加速度、加加速度运动时GPS接收机的载波与伪码同步问题。更多还原

【Abstract】 GPS is an exact satellite navigation system, it has many merits, for instance, high precision, all weather and globosity, so it is regarded and applied in military and civilian domain widely. Owing to facing users, GPS receiver has great development and new productions appear ceaselessly and the frequency of update expedites.It is the precondition of normal movement that the system can track satellite signal steadily in GPS receiver, so the tracking technique is a disquisitive emphases all along. In the high dynamic condition, the received satellite signal takes Doppler frequency shift by carrier high-speed movement, and the frequency shift may attend by acceleration and quadric acceleration, it causes the change of carrier wave frequency and pseudocode delay, it is key to settling the question that how let the carrier wave and the pseudocode of receiver keep synchronization with the carrier wave and the random code of GPS signal.The thesis analyses the structure of spatial GPS signal firstly, afterward in the base of Phase Locked Loop, analyses the the algorithm of phase discriminator and frequency discriminator in carrier wave loop and the algorithm of phase discriminator in code loop, accomplishes comparison to all algorithm by simulation, introduces the principium of the filter of loop and numerical controlled oscillator. It analyses the origin of measure error in loop, on the base, bring the way about choosing tracking threshold and loo(?) bandwidth. Lastly, the thesis gives two tracking loop schemes to adapting high dynamic circumstance according as the assistant of frequency locked to phase locked, proves the validity and rationality of the schemes by simulation, and solves the question of carrier wave and pseudocode synchronization in condition of carrier movement with the acceleration and quadric acceleration.更多还原