A new method for satellite motion correction in TWSTFT

It is almost reciprocity of the Two-way satellite time and frequency transfer(TWSTFT) communication links. The path delays are almost canceled out due to the symmetry. It is the advantage of TWSTFT. But as the technology development, the higher accurate is required for time comparison. The incomplete reciprocity must be studied in detail for TWSTFT. Satellite motion is a kind of the incomplete reciprocity and can result that the uplink geometry paths aren´t equal to the downlink geometry paths. Satellite motion´s correction depends on the satellite velocity and time difference between the signal from two stations arrive at the satellite.