GNSS接收机晶振频率稳定度仿真分析

Simulation analysis on frequency stability of crystal oscillator in GNSS receivers

针对全球卫星导航系统(GNSS)提供的高精度定位、导航及授时(PNT)服务以精密测量的传输时间为基础,然而GNSS接收机中普遍采用的频率源为稳定度较差的晶振的问题,提出一种对GNSS接收机晶振频率稳定度进行分析和建模的方法:根据GNSS接收机晶振频率稳定度受随机频率误差及老化率的影响的原理,给出晶振随机频率误差及老化率的数学模型;并根据不同随机频率误差成分仿真相应的各项晶振随机频率误差序列;同时基于LAG1自相关法辨识不同时期主导的随机频率误差类型,定性分析其对晶振频率稳定度的影响。实验结果表明,提出的方法可为GNSS接收机晶振设计及频率稳定度能评估提供参考。

Aiming at the problem that the high-precise positioning,navigation and timing(PNT)services provided by the global navigation satellite system(GNSS)are based on precisely measured transmission time,but the frequency source commonly used in the GNSS receivers is crystal oscillators with poor stability,the paper proposed an analysis and modelling method of the frequency stability of crystal oscillator in GNSS receivers:according to the principle that the crystal frequency stability of GNSS receivers is affected by random frequency error and aging rate,the mathematical model of the random frequency error and the aging rate was given;and the corresponding random frequency error sequences of crystal oscillator were simulated according to different random frequency error components;meanwhile,the dominant random frequency error types in different periods were identified based on the LAG1 autocorrelation method,to qualitatively analyze their influence on the frequency stability of crystal oscillator.Experimental result showed that the proposed method could provide a reference for the design of crystal oscillator in GNSS receivers and the performance evaluation of the frequency stability.