中文摘要：

系统时间性能是导航卫星极其重要的技术指标，对其实施有效评估是导航系统建设和运行提出的迫切需求。本文研究了基于卫星双向时间频率传递技术的导航系统时间评估方法，给出了双向时间频率传递技术理论算法和数学模型，并利用该方法处理了3个多月的北斗卫星C波段双向观测数据，得到BDT（北斗时）相对UTC（NTSC）的钟差。根据钟差结果，计算了北斗卫星系统时间的频率准确度和稳定度。

英文摘要：

Time performance is a key index in satellite navigation system, and there is a pressing need for time performance evaluation in the system construction and operation. In this paper, we make a research on the performance evaluation methods of navigation time system based on TWSTFT（ Two - way Satellite Time and Frequency Transfer） method and give the algorithm and model of TWSTFT. Moreover, we study C - band two - way satellite observation data over three months using this method and ob- tain the clock bias between BDT and UTC （ NTSC ）. Finally, we calculate the frequency accuracy and the frequency stability based on the clock bias results.