GPS伪卫星信号捕获的仿真分析与研究

GPS伪卫星是模拟GPS卫星信号的地面发射设备。其终端接收设备的射频前端将天线接收到的伪卫星信号变换为中频信号,再经模拟数字转换,便可得捕获的原始信号。采用专用集成电路设计的GPS接收机极大地限制了用户对原始信号的性能分析和新算法的开发,而基于FPGA DSP架构的设计能提高研究的自由度。本文先对GPS伪卫星信号的形成和接收机的结构作扼要介绍,再对伪卫星信号的搜索算法和捕获性能做分析,并通过频域FFT实现仿真。结论表明,通过仿真技术能有效地复现出了捕获的GPS伪卫星信号。

Simulation Analysis and Study of Signal Acquisition of GPS Pseudolite

A GPS pseudolite is a ground transmitter equipment which can simulate GPS satellite signals. The pseudolite signal received by the RF front end of its terminal receiving equipment is converted to the IF signal and then the IF signal is processed by an analog-to-digital converter.Thus,the acquired raw signal can be derived.Although the GPS receivers designed by ASIC can extremely limit the users in analyzing the performance of the raw signal and developing new algorithms,a new design based on a FPGA DSP architecture can improve the freedom for further study.In this paper,the formation of the GPS pseudoUte signal and the architecture of the receiver are presented in brief firstly.Then,the search algorithms and acquisition performance of the pseudolite signal are analyzed.Finally,the whole process is simulated by using the frequence-domain method of FFT.The result has shown that the acquired GPS pseudolite signal can be effectively reproducted through simulation.