北斗在轨卫星钟中长期钟差特性分析

针对北斗在轨卫星Rb原子钟2013年的实测数据，采用二次多项式拟合得到BDS卫星钟差模型，采用哈达玛总方差公式计算了北斗卫星钟的短期频率稳定度指标，进而分析了北斗在轨卫星钟特性指标的变化规律。通过实例计算，揭示了BDS不同在轨卫星钟的相位、频率、频漂及残差指标的变化规律；计算得出BDS卫星钟万秒频率稳定度维持在10-13量级左右，其中GEO卫星钟的稳定度相对较差，4号和8号卫星在运行期间出现跳变，跳变之后稳定性得到提高，其他在轨卫星钟稳定度变化趋势则相对平稳。

Analysis of the Mid-long Term Characterization for BDS On-orbit Satellite Clocks

Rb clock products of BDS on-orbit satellites in 2013 are used to analyze the satellite clock qualities such as frequency stabilities and clock noise level. Quadratic polynomial model is used to fit BDS satellite clock offsets. The short-term frequency stabilities are achieved using Hadamard total variance method. Based on above indexes, BDS satellite clock characteristics which include phase, frequency, frequency shift and residual indexes have been analyzed. It can be concluded by the actual numerical examples that, the frequency stabilities of BDS satellite clocks in ten-thousand seconds is about 10-13. The stabilities of GEO satellite clocks are worse than that of the other satellite clocks. The satellite clocks of PRN04 and PRN08 have phase jumps during running time, and the stabilities of these satellite clocks have been enhanced after jump times. The stabilities of other satellite clocks are relatively steady. In general, the qualities of MEO satellite clocks are better than that of GEO and IGSO satellite clocks.