| High-precision clock synchronization technique become more and more important in both fields of military and civilian, particularly its application prospect in the Beidou satel ite navigation system is quite broad.Time delay calibration is the key technique in clock synchronization, where the former has been the accuracy limiting factor for the latter. The main objective of this thesis is to study the equipment delay calibration techniques in Beidou satellite navigation system.The main contents include:(1) Specifications on time delay calibration techniques for clock synchronization in satellite navigation system are analyzed as the basis of the thesis. Comparison study is conducted in-between methods of two-way clock synchronization and satellite common-view clock synchronization, in which working principles and sources of uncertainty of both methods are analyzed in depth.(2) Design and verification on equipment time delay calibration method specifically for Beidou time comparison system.Current absolute time delay calibration method is not realistic to adopting large enough reflector antennas, therefore it has drawback that in-situ overall system calibration cannot be implemented. To avoid such drawback, this thesis proposed an absolute delay calibration method through wireless connection: Simulated satellite launch system is accurately calibrated form a loop together with the testing receiving link, to calibrate absolute time delay within the receive link. The method is proved to be very effective, with uncertainty of only 0.6ns. Furthermore, relative time delay calibration experiments are also implemented according to the principle of GPS relative time delay calibration, the relative delay calibration uncertainty is shown to be about 1.5ns.The results of this thesis can be directly applied in to common-view time synchronization devices based on Beidou satellite system, also as guidance for future development of two-way satel ite clock synchronization system. |
PDF Full Text Request