GNSS精密时频接收机时钟调控模型与参数设计方法

GNSS Precise Time-Frequency Receiver Clock Steering Model and Parameter Design Method

实时精密单点定位(real time precisepoint positioning,RT-PPP)技术可实现亚纳秒级、天稳定度达到1×10^(-14)量级的全球导航卫星系统(global navigation satellite system,GNSS)单向授时。时钟调控直接影响输出时频信号的稳定度性能,但调控参数不合适时将破坏振荡器的短期稳定度。面向振荡器短期稳定度和RT-PPP长期稳定度最优组合,构建了RT-PPP时频接收机的锁相环时钟调控模型,分析了调控系统噪声,提出了一种二阶锁相环调控参数设计方法。利用RT-PPP时频接收机对所提出的调控模型和参数设计方法进行了实测验证,结果表明,利用所设计的时钟调控模型和参数,RT-PPP时频接收机的频率稳定度可达秒稳4.3444×10^(-12),天稳1.1029×10^(-14),在时间间隔小于300s时与铷钟自由振荡稳定度基本一致,大于300s时与RT-PPP稳定度基本一致,能很好地组合振荡器短期稳定度和RT-PPP长期稳定度优势。

Objectives:Real time precise point positioning(RT-PPP)technology can realize one-way timing with sub-nanosecond precision and daily stability of 1×10^(-14) level.Clock steering affects the stability of the receiver's output time-frequency signal,however,inappropriate clock steering parameters can degrade the short-term stability of the receiver's oscillator.Methods:To combine the short-term stability of the oscilla-tor and the long-term stability of the RT-PPP,we propose a phase-locked loop clock steering model for the RT-PPP time-frequency receiver.The noises of the system are analyzed.And the parameter design method of the second-order phase-locked loop is proposed.Experiments were carried out with the clock steering model and designed parameters used in the RT-PPP time-frequency receiver.Results:Experimen-tal results show that the frequency stability of the RT-PPP time-frequency receiver is 4.3444×10^(-12) at 1 s,1.1029×10^(-14) at 1 d,the frequency stability of the time intervals shorter than 300 s can get close to the free-running Rubidium clock,the frequency stability of the time intervals longer than 300 s can get close to the RT-PPP.Conclusions:The proposed clock steering model and parameter design method can well realize the combination of the oscillator's short-term stability and the RT-PPP's long-term stability.