Algorithm Research And Implementation Of Low Earth Orbit Satellites Spaceborne GNSS Receiver Antenna Phase Center Calibration

After the success of precision orbit determination(POD)from the Topex/Poseidon(T/P)marine satellite for the first time using spacebome GNSS POD technology,the spaceborne GNSS POD technology has been become the first method for low earh orbit(LEO)satellites with prominent advantages of GNSS technology.As more and more LEO satellites launch in China,how to further improve the orbit determination accuracy and ensure the satellites safety has become a research hotspot.Based on the spaceborne GNSS POD technology,this paper focuses on the influence of the LEO satellite spaceborne GNSS antenna phase center model on POD,and studies the in-flight estimation algorithm and implementation.The main contents and conclusions of this paper are as follows:(1)On the basis of the theory of LEO precise orbit determination,observation equation,observation error and corresponding correction measures are expounded.The quality evaluation index of GNSS data and orbits precision are given by real measured data experiment.At the same time,the influence of orbit determination strategy on precise orbit determination is studied with examples,especially the setting of random pulse.(2)The in-orbit estimation theory and algorithm for PCO and PCV models are discussed in detail.The feasibility of PCO estimation and the PCV model estimation method are studied through examples.The phase center model of LEO satellite spaceborne GNSS antenna and its correction strategy are described.Taking GRACE A,GRACE B and CHAMP as test satellites,the influence of phase center model on precision orbit determination is studied by using real data.The prior phase center model and the in-flight phase center model have apparent changes,so the in-flight estimation phase center model is necessary.(3)The precise orbit determination tasks of ZY-3,FY-3C and HY2A are realized,and the estimation of phase center models of the satellite borne GNSS antennas is carried out.Through experiments,it is difficult to separate the PCO from the experiential parameters in the x and y directions,and it is feasible to estimate PCO in the z direction only.About in-flight estimation of PCV model,the direct method and the residual method can both achieve in-flight estimation and their respective advantages and disadvantages coexist.In addition,the influence of PCV model resolution on precision orbit determination is studied.Considering the computational efficiency,storage space and space and other factors,residual method to estimate PCV model of 5°is a better choice.