Methods On Calibration Of Equipment Time-delay Of Satellite Ground Station For Satellite Orbit Determination With Transfer Mode

Satellite orbit determination with transfer mode is the important technical support of the navigation satellite system by transfer. In the system of satellite orbit determination with transfer mode, high-precision measurement of the distance between satellite and ground station which is based on the measurement of pseudo-range is the foundation of precise satellite orbit determination. In order to accurately determine the distance between satellite and ground station,we need to deduct the station equipment time-delay included in the pseudo code ranging information. As a result,the calibration accuracy of the equipment time-delay is the key to improve the precision of the satellite orbit determination,also is the key to improve the precision of satellite navigation system service. With regard to calibrate the equipment time-delay for satellite orbit determination with transfer mode,main work and study of this paper are as follows:(1) Introducing the equipment composition of ground station for satellite orbit determination with transfer mode. According to the type of ground station equipment,giving the definition of the equipment time-delay of ground station.(2) Using the homologous zero baseline measurement methods,and deducing the principle of the equipment time-delay of ground station which is based on observation model for satellite orbit determination with transfer mode. Establishing the corresponding mathematical model and analyzing the error correction for the signal propagation path. In the process of the error correction,we especially considered the influence of the geometric path delay error and clock difference error between the ground station on the calibration results of the equipment time-delay of ground station.(3) The C band satellite orbit determination network run by National Time Service Center(NTSC) was used to proceed experiments. Six sets of 5m antenna ground station and a set of 3.7m antenna ground station were installed in Lintong. At the same time,keeping the equipment of the ground station use the same clock. The modes of the station equipment time-delay included the two-way satellite time comparison,receiving own disseminated,a station receive own disseminated and other stations receive the disseminated, a station receive own disseminated and other disseminated at the same time.(4) The data of the experiment was processed,and the geometric path delay error was corrected by using the ground station coordinates and satellite orbit data, the clock difference error between the ground stations was corrected by using the data of the clock difference measured by the time interval counter. The results show that using homologous zero-base line measurement to calibrate the equipment time-delay of the ground station is simple and feasible. The calibration accuracy of the equipment time-delay reaches a sub-nanosecond magnitude. This calibration of the equipment time-delay has an important significance on the precise satellite orbit determination with transfer mode,also has an important significance on the clock difference between measuring station and the maintain of the system time benchmark.