微弱信号下基于模糊度解算的辅助式GPS接收机定位算法研究

Method for assisted-GPS positioning based on ambiguity resolution in weak signal environment

提出了一种辅助式GPS接收机定位解算方法,基于该方法接收机不需要解调导航电文、帧同步和位同步,仅需要对GPS信号进行伪码相位测量,在获取卫星星历、卫星钟差参数等辅助信息的基础上完成定位解算。该算法在常规GPS定位算法基础上,增加伪距中模糊部分为未知数,当接收机位置坐标和接收机钟差的迭代初值误差满足一定条件时,消除了伪距中模糊度影响。然后推导了该算法的定位方程,给出了定位流程。最后仿真实验证实了该算法的有效性。

An assisted-GPS positioning algorithm was proposed. Based on this algorithm, the receiver needn＇t accomplish the bit synchronization, frame synchronization and navigation data demodulation, which were usually necessary for the conventional GPS receiver, it could implement the positioning solution only by the measurement of pseudo-code phase and the assistance data （including ephemeris information and satellite clock corrections etc.）. Compared with the conventional GPS positioning algorithm, the proposed algorithm increases the ambiguity of the signal transmission time as an unknown parameter for the pseudorange equation. When the initial errors of approximate location and receiver＇s clock bias were subjected to a constraint domain, the ambiguity of the signal transmission time could be eliminated. Then, the iteratively equation for this algorithm was derived, and the main steps were summarized. The simulation results show the validity of the algorithm.