The impact of GPS ephemeris on the accuracy of precise orbit determination for LEO using GPS

Today more and more Low Earth orbiting satellites (LEOs) of new scientific missions are equipped with a GPS receiver for precise orbit determination (POD),on-board GPS has become one of the main POD approaches.However,the on-board GPS POD accuracy obviously relies on the accuracy of GPS orbit and clock products.Based on the zero-difference dynamic POD approach of SHORDE-III program,this paper shows the in- fluence of GPS orbit and clock on the POD accuracy of LEO using real GRACE data and three types of IGS orbit products between 1 Aug.and 7 Aug.The results indicate that IGS final precise orbit product (igs) and rapid orbit product (igr) have the equal POD ac- curacy which is about 9.5cm,the POD accuracy using ultra-rapid orbit product (igu) is about 10.5cm which is a little worse than igs and igr;High-rate GPS clock products havre an impact of about 1～6 cm on the POD accuracy of LEO.