基于星间链路的导航卫星时间自主恢复策略

Time Recovery Strategy of Navigation Satellite Based on Inter-satellite Link

基于北斗导航卫星星间链路的测距与数传功能,针对自主导航时卫星时频子系统异常导致载荷系统断电重启的情况,提出了一种基于星载计算机自主计时及星间链路误差校正的策略.在载荷系统重启时间内,利用星载计算机守时,并通过十秒稳定度预报晶振频率漂移量的方法,维持星钟在重启时间内的稳定.载荷系统重启后,星载计算机授时给导航任务处理机,通过误差分析计算出总误差.该误差在星间链路建链误差允许范围内,然后通过星间链路对星钟误差进行校正恢复,重新实现星地时间同步.

When the Beidou navigation satellite is on autonomous navigation,the satellite timefrequency system abnormality will cause the load time system to power off and restart,which is an intrackable problem.For this reason,a new strategy is proposed using ranging and data transmission functions of the Beidou inter-satellite link.Due to the stability and accuracy of the current on-board computer crystal oscillator,the method of using ten-second stability for predicting crystal frequency drift to calculate satellite time instead of the crystal oscillator is proposed to make sure the satellite clock is stable during the restart time of the load system.With this method,total error can satisfy the allowable range of inter-satellite link construction error.After the load system is restarted,the on-board computer gives the navigation task processor a standard time and total error is calculated through error analysis system,which can also meet inter-satellite link standard.The satellite clock error can be fixed through the inter-satellite link to re-synchronize the satellite time and ground time.