High Orbital Spacecraft Fast Positioning Algorithm Assisted by Inter-Satellite Links

Traditional algorithm of the transmission time milliseconds reconstruction for GNSS signal receiver has a problem that when the receiver's approximate position is unknown, the calculating amount increases sharply, so that traditional algorithm is inapplicable on this condition. A fast positioning algorithm of navigation receiver assisted by inter-satellite link (ISL) is proposed in this paper by utilizing the high-speed data transmission and ranging function of ISL. To ensure that when the receiver position is completely unknown, this algorithm can calculate receiver’s outline position by us of the ISL’s time-division signal to complete ranging and the ISL’s high speed data transmitting signal to acquire the satellites’ positions of GNSS constellation. Firstly, ISL ranging results with complete signal transmission time is made use of to finish rough positioning using. Secondly, take advantage of the approximate position to resolute integer millisecond ambiguity of navigation signal. Finally, by using the pseudorange of fast reconstruction of all visible, satellites precise positioning is achieved. Verified by simulation with the CE-5T flight experiment parameters, the GPS ephemeris parameters and ISL’s signals, fast positioning can be achieved on the full part of the high orbital spacecraft operating on the transfer section of earth-moon orbiter. Compared with the original downlink navigation signal, the first positioning time can be reduced by about 1/6.