关键词: 星间链路, 锚固站, 单程Ka伪距, 设备时延, 钟速改正

Abstract: The Ka-band pseudoranges measured between satellites and between satellites and anchor stations provide the third-generation BeiDou navigation satellite system (BDS-3) an alternate approach to achieve orbit determination (OD) and time synchronization (TS) which is completely independent of monitoring stations. In this paper, by modeling the clock offsets with piece-wise linear polynomials, we directly process the inter-satellite (IS) and satellite-ground Ka-pseudoranges to conduct integrated OD and TS with simultaneously estimation for the hardware delay of anchor stations. Experiments with real Ka-pseudorange data observed at 8 BDS-3 satellites and 2 anchor stations are carried out. It is demonstrated that, with the broadcast clock drift corrections, the RMS of IS Ka-pseudorange residuals is 0.052 m; the accuracy (RMS) in radial direction of the estimated and predicted orbits are 0.016 and 0.033 m, respectively; the accuracy (95%) of the estimated and predicted clocks are 0.038 and 0.992 ns, respectively. The standard deviations of estimated hardware delays of anchor stations are smaller than 0.5 ns. The proposed method is adaptable as it also works even if no predicted clock drift is available. In this extreme case, the RMS of the IS pseudorange residuals is dramatically increased by 242%; However, the accuracies are 0.021 m and 0.041 m for the estimated and predicted orbits, respectively, while 0.040 ns and 1.092 ns for the estimated and predicted clocks, respectively.

Key words: inter-satellite link, anchor station, one-way Ka-pseudorange, hardware delay, clock drift correction