晶振对飞行器时频同步系统的影响

The effect of crystal oscillator on the flight vehicle time and frequency synchronization system

飞行器时频同步系统采用双向伪距测量,伪距信息通过测量信号到达时间获得。由于晶振在飞行平台上处于振动和动态状态,与地面静态场景受到的影响不同,因此对晶体振荡器的选择和应用十分重要。本文介绍了晶振老化率、晶振频偏的影响,构建了由各类误差源引起的跟踪环路误差模型。仿真结果表明,振动引起的晶振相位噪声和阿伦偏差晶振相位噪声随环路带宽增大而减小,随环路阶数增大而增大;选用高稳定度,g敏感度小的晶振可降低环路跟踪误差;将阿伦偏差作为晶振选择的指标具有较大的实用意义。

The flight vehicle time-frequency synchronization system uses bi-directional pseudo-range measurement,and the pseudo-range information is obtained by measuring the signal arrival time.The crystal oscillator is in vibration and dynamic state on the flight platform,which is affected differently from the static scene on the ground,so it is very important for the selection and application of crystal oscillator.In this study,the effects of crystal oscillator aging rate and crystal oscillator frequency bias are introduced,and the tracking loop error model caused by various error sources is constructed.The simulation results show that the phase noise of crystal oscillator caused by vibration and Allan’s deviation decreases with the increase of loop bandwidth,and it increases with the increase of loop order;the selection of crystal oscillator with high stability and small sensitivity can reduce the loop tracking error;the Allan’s deviation as the index of crystal oscillator selection has a greater practical significance.