Space Signal And Atomic Clock Performance Monitoring And Evaluation Based On IGMAS

Satellite navigation has become more and more closely related to a series of activities such as national defense,life and rescue.Therefore,the monitoring and research of satellite navigation performance is becoming more and more urgent.Since the accuracy of spatial signals and the performance of on-board atomic clocks are the decisive factors for positioning accuracy and timing accuracy in satellite navigation,China's International GNSS Monitoring Assessment System?iGMAS?,which is built in response to the international call still needs further improved.Therefore,this paper is based on iGMAS ephemeris data and clock data,takes spatial signal accuracy and atomic clock performance as the research content.In this paper,the accuracy of spatial signals and atomic clock indicators are studied separately.The ephemeris and clock products of major satellites under iGMAS are monitored and evaluated,and the performance of each system and each satellite is analyzed.The solution to the spatial signal part is to preprocess the ephemeris data using the Lagrangian interpolation theorem,substituting the processed data into the corresponding solution formula.At the same time,the antenna phase error and the group delay error are corrected.Then,the URE indicators are obtained via the segmentation method.And the URRE and URAE indicators are obtained by the difference method.The solution to the atomic clock part of the space is based on the definition formula of the index,based on the least squares fitting solution method,the satellite clock data is solved and the accuracy and drift rate of the satellite atomic clock are obtained.The three kinds of variance sampling methods of Hadamard,Allan and modallan were used for comparison in stability,and the monitoring results of atomic clock stability were obtained by comprehensive evaluation.The magnitudes of URE,URRE and URAE of the spatial signal are 5m,1mm/s and10^-3mm/s² respectively;the accuracy,drift rate and stability of the atomic clock are 10^-11,10^-18,10^-14.Finally,by comparing the experimental results of iGMAS and IGS,it is concluded that the data products under iGMAS in China have already had the evaluation ability in terms of spatial signal accuracy and on-board atomic clock performance,but the accuracy still needs further improvement.