中文摘要：

针对星上缺乏系统时间会出现钟差整体漂移的问题,本文提出两种新的钟速初值预报方法建立集中处理模式下星上系统时间算法：用每颗星第1天的前两历元的钟差预测钟速初值和用每颗星每天的前两历元钟差预测钟速初值。仿真结果表明,算法合理,两种方法得到的自主系统时间与国际全球导航卫星系统服务时间（IGST）相比,60天的偏移程度均在100 ns以内,用每颗星第1天的前两历元的钟差预测钟速初值建立的系统时间稳定性更好。

英文摘要：

Clock offset drifts occur for the lack of inter-satellite system time. In the ensemble working mode, inter- satellite system time algorithms are proposed in this paper. The two prediction methods of initial value of clock-velocity are put forward for building system time, i.e. initial value of clock-velocity is predicted by using former two clock offsets of first day, and is predicted by using former two clock offsets of each day. Simulation results show that the two algorithms are reasonable. The new system time is compared to international GNSS （Global Navigation Satellite System） service time （IGST） ; the clock offset drift of 60 days is less than 100 ns. The system time built by use of the first prediction method is more stable.