Study On Calibration Methods Of Equipment Time-delay Of Ground Station For Satellite Orbit Determination By Transfer Tracking

The accuracy of satellite orbit tracking affects directly the accuracy of system positioning,timing,and speed measurement in satellite navigation systems.Therefore,improving the accuracy of satellite orbit determination is a hot topic for all major global navigation systems for satellite navigation systems.The existing satellite ranging measurement of all major satellite navigation systems are based on radio ranging.The calibration accuracy of ground station equipment delay affects directly the final ranging accuracy in the radio ranging system.Improving calibration level of equipment time-delay of ground station for orbit determination by transfer tracking becomes an important measure to further improve the system performance indicators,in order to maintain the advantages of the orbit tracking technology by transponder mode,and improve the accuracy of orbit determination by transfer tracking.Increasing calibration level of equipment time-delay for orbit determination by transfer tracking system is mainly from two aspects: reducing random error and improving system error measurement level.This paper mainly did the following research work based on this purpose:Firstly,we analyzed the calibration principle and problems of the equipment time-delay calibration method of ground station in the satellite orbit determination by transfer tracking;we analyzed the relationship between power,C/N ratio,temperature,relative humidity and other factors affecting random error of ground station equipment,and the time delay of equipment.We also provided control and observation schemes for reducing random errors.Secondly,we analyzed the delay data of various measurement equipments in the past and found that the device data with good continuity and good stability only make the orbit accuracy best.Thirdly,we observed MEASAT-2 and APSTAR 7 using GEO 3.7-meter antenna in transponder satellite orbit measurement system from NTSC(National Time Service Center).We performed small-antenna delay calibration,radio-frequency cable delay calibration,and mobile station delay calibration tests,respectively.Lastly,we deal with the test data,performed accuracy evaluation,and analyzed and compare the accuracy and stability of the calibration results of the three time delay calibration methods from various perspectives such as orbit measurement error,orbit determination residual error,and orbit determination accuracy.The small antenna delay calibration method with better continuity and stability is the optimal time delay calibration method.