Determination of CHAMP Orbit from Onboard GPS Double-Difference Phase Data with Dynamic Method

In order to determine the CHAMP's orbit,the onboard GPS data of CHAMP,the GPS data of IGS tracking stations,EOP,SGO and time data are necessary.The GPS data should be pre-processed to correct the clock error,solve the ambiguity,detect the cycle slips,determine the satellite attitude,and calculate the antenna phase center offset and correction.Then the air-ground GPS double-difference phase observations are constructed.The CHAMP's orbit is really determined with the dynamic method.Comparing with the PSO from German GFZ,the precision(RMS) in the radial direction is 0.285 7 m.For the 1-day overlapping orbit,the RMS of radial orbit difference is 0.095 8 m.Comparing the orbit endpoints,the mean difference of radial orbit is 0.066 6 m.