GPS伪随机码的软件和硬件仿真实现

Implementation of Software Simulation and Hardware Simulation for GPS’ Pseudo-random Noise Code

摘要:

目前四大全球卫星导航定位系统中,美国的GPS是发展最早也是应用面最广的系统,GPS提供民用的标准定位服务和军规的精确定位服务;为研究GPS卫星导航电文的产生机理和针对GPS的导航对抗技术,在详细介绍GPS伪随机码的基本原理和C/A码生成电路的基础上,通过MATLAB和FPGA分别对C/A码进行了软件和硬件仿真实现;基于MATLAB的软件仿真采用循环程序实现了m序列和C/A码,基于FPGA的硬件仿真首先构建一个D触发器元件,然后利用该元件通过并行指令实现m序列,最终生成C/A码;两种方法虽然采用不同的思路和技术,但是得到了一致的C/A码信号样式;伪随机码的产生是GPS实现扩频通信的重要环节,通过对GPS伪随机码的仿真实现,有助于对GPS卫星信号的捕获研究和针对GPS的欺骗式干扰研究。

Abstract:

At present,in the four global satellite navigation and positioning systems,American GPS is the earliest and widely used system. GPS provides Standard Positioning Service (SPS) and Precise Positioning Service (PPS). For studying the navigation data of GPS and the Counter Technology to GPS,this paper introduces the basal theory of GPS’ Pseudo-random Noise Code and the circuit which produces the C/A code. Then it emulates the C/A code of GPS by MATLAB and FPGA. The software simulation by MATLAB uses the circular sentences to implement the m-sequence and the C/A code. The hardware simulation by FPGA produces a D-Trigger first,then it uses the D-Trigger and parallel sentences to implement the m-sequence and the C/A code. Although the two methods use different thinking and technologies,they get the same C/A code. GPS’ Pseudo-random Noise Code is the important segment to spread spectrum communication. This study to GPS’ Pseudo-random Noise Code will contribute to the research on capturing GPS signal and deception jamming to GPS.