The method on determining invisible satellite-ground clock difference with inter-satellite-link

Usually, satellite-ground clock difference of invisible arc is obtained by predicting. This paper proposes determining satellite-ground clock difference of invisible arc by way of inter-satellite link, using target satellite connecting station with relay satellite. Target satellite and station consists of satellite-ground link, target satellite and relay satellite consists of inter-satellite link. It analyzes relay-satellite angle. When more relay-satellites exist, clock difference of invisible arc is determined with weight. The result shows: time-synchronization precision of satellite-ground is less than 0.3ns, std is less than 0.3ns.