REN Ye^1,2, XUE Yan-rong^1,2,3, LI Xiao-hui^1,2

(1. National Time Service Centre, Chinese Academy of Sciences, Xi'an 710600, China;

2. Key Laboratory of Precision Navigation and Timing, National Time Service Centre,

Chinese Academy of Sciences, Xi'an 710600, China;

3. University of Chinese Academy of Sciences, Beijing 100039, China)

Abstract：The effect of the difference of the time delay, which results from the two-way nonreciprocal geometric path due to the clock offset between the two stations and the satellite motion, on the results of TWSTFT (two-way satellite time frequency transfer) is analyzed. A simulation is conducted for 9 links of TWSTFT, which relate to 3 satellites(chsat-1, BD-3G, IGSO70) and 3 pairs of station(Beijing—Chengdu, Beijing—Kashi, Beijing—Sanya). The simulation shows: 1)when the clock offset between the two stations is between 1 ms and 10 ms, the effect of two-way nonreciprocal geometric path via GEO satellite on the result of TWSTFT, i.e. τ value, is less than that via IGSO satellite; 2)when the clock offset between the two stations is less than 1 ms, the effect of two-way nonreciprocal geometric path via GEO satellite on the result of TWSTFT, i.e. τ value, is in the order of picosecond and can be ignored, while that for the path via IGSO satellite is in the order of nanosecond and final to be ignored.