北斗系统星载原子钟周期性波动的频谱分析校正方法

在建立卫星导航系统星座自主守时时间基准时,必须消除星载原子钟钟差数据中包含的周期性波动,以免将其引入系统时间。针对这一问题,基于国际卫星导航服务组织(International GNSS Service, IGS)提供的北斗系统星载原子钟钟差产品,提出了一种基于频谱分析的星载原子钟周期性波动校正方法。通过比较校正前后钟差数据的频率稳定度性能差异,确认该方法能够消除由环境因素引起的钟差数据周期性波动。北斗系统各类卫星星载原子钟的性能在校正后都得到了提升。地球同步轨道卫星星载原子钟的万秒频率稳定度提升50%左右,中轨道地球卫星星载原子钟的万秒频率稳定度提升23%左右,倾斜地球同步轨道卫星星载原子钟的万秒频率稳定度提升15%左右。经过校正,北斗二号和北斗三号系统中的星载原子钟普遍达到了地面站铯钟的频率稳定度性能,为完全基于星载原子钟的星座自主守时提供了基础。

Correction method for periodic fluctuation of the BDS satellite atomic clocks based on spectrum analysis

In order to avoid introducing periodic fluctuations in the clock offset of onboard atomic clock into the system time, it is necessary to eliminate the periodic fluctuations when establishing the autonomous time benchmark of satellite navigation system constellation. Based on the clock offset of BeiDou atomic clock provided by IGS, a method of periodic fluctuation correction for onboard atomic clock based on spectrum analysis was proposed. By comparing the performance of frequency stability of onboard atomic clock offset before and after correction, it is proved that this method can successfully eliminate the periodic fluctuation of satellite clock offset caused by environmental factors. Performances of different types of onboard atomic clock of BeiDou are improved after correction. Through this method, performances of onboard atomic clocks with different orbital types in the system have been improved remarkably. Among them, the frequency stability in 10 000 seconds of GEO(geostationary satellite) satellite-borne atomic clocks has been improved about 50%, MEO(medium orbit earth satellite) about 23%, and IGSO(inclined geosynchronous orbit satellite) about 15%. Through this correction method, the frequency stability of cesium clocks in ground stations has been achieved in both BDS-2 and BDS-3 satellite-borne atomic clocks, which lays foundation to the star autonomous timekeeping based entirely on satellite-borne atomic clocks.