Research On Satellite Real-time Orbit Determination Method Based On Doppler Measurement

With the deepening of space research and application,the requirements of real-time,autonomy and accuracy of satellite orbit determination are becoming more and more strict.Since Doppler observation has the characteristics of high precision and good versatility,it has been widely used in aerospace monitoring and control field.The French DORIS system has realized the decimeter level real-time orbit determination based on the ground Doppler measurement,which is in the leading position of the world,and thus can be taken as a good reference for our country to realize the satellite's high-precision real-time orbit determination.Therefore,this paper explores how to realize the real-time orbit determination using Doppler observation in different orbital altitude satellites,mainly from the following aspects:1.The real-time orbit determination method of Doppler measurement of LEO satellite is studied.According to the basic principle of Doppler measurement and the movement characteristics of LEO satellite,the equations of measurement and the state equation of the real-time orbit determination are deduced respectively.The real-time orbit determination method based on extended Kalman filter is studied,and the optimal operating condition of Kalman filter is discussed.Taking the HY-2A satellite with DORIS receiver as an example,the real-time orbit determination method of Doppler measurement is simulated and verified.2.The error correction method of the Doppler measurement of the LEO satellite and the real-time orbit determination accuracy of the measured data are analyzed.In order to solve the problem of frequency offset error,ionospheric error,tropospheric error and center-of-mass error in measured data,the characteristics of error,correction principle and magnitude of influence are analyzed.The measurement equation and equation of state suitable for the orbit determination of the measured data are determined,and real-time orbit analysis of HY-2A and JASON-2 satellites is completed using the measured data of DORIS2.2 format.3.A real-time orbit determination method for Doppler measurements of medium and orbital altitude satellites is proposed.With regards to the reality that the DORIS system does not support the orbit determination of the higher orbit satellite,the real-time autonomous orbit determination method of the single satellite of the medium or high orbit satellite based on the MEO constellation is studied,according to the development trend of the satellite autonomous orbit determination technology.The STK is used to build the simulation scene,and the inter-satellite Doppler shift characteristics and the orbit determination effect of different types of observation combinations are analyzed and compared with the inter-satellite pseudorange measurement orbit determination.The results show that the higher real-time orbit determination accuracy can be achieved by using Doppler shift as the observation for the satellites with different orbital heights.DORIS system has the advantage of realizing the real-time orbit determination of LEO satellites.The real-time autonomous orbit determination technology of medium and high orbital height satellites based on inter-satellite Doppler measurement is feasible.Doppler observation can also be used as a supplement or backup to other observation means to achieve satellite real-time orbit determination.