Impact of satellite motion on two-way satellite time and frequency transfer

The impact of satellite motion on two-way satellite time and frequency transfer (TWSTFT) is analysed. Due to the two distances from two stations to the satellite being different, the non-reciprocal paths are produced, which impact the accuracy of TWSTFT. Choosing a satellite for which both elevations are about the same can minimise the effect, or offsetting the transmission time can eliminate this. In addition, due to the Earth´s rotation and the finite signal velocity the non-reciprocal paths are also produced, and the error mainly results from the aviation of the satellite longitude and altitude.