BDS/GPS/LEO precise point positioning based on fourier series fitting LEO orbit error

In view of the problems that most of the low earth orbit (LEO) constellation designs are in the preliminary demonstration stage, the LEO orbit cannot be accurately obtained, and the orbit error is difficult to express accurately, BDS /GPS/LEO precise point positioning (PPP) based on Fourier series fitting LEO orbit error is proposed. Since the orbit error presents a quasi-periodic sinusoidal characteristic, the Fourier series is used to fit the LEO orbit error, and the LEO observation data and ephemeris products are generated by simulation. Finally, the influence of LEO orbit error on the accuracy and convergence time of BDS/GPS/LEO PPP is analyzed. The simulation results show that the BDS/GPS/LEO PPP error increases gradually with the increase of the LEO orbit error, but it is not significantly related to the station latitude and the LEO constellation configuration. And in order to ensure the convergence time of BDS/GPS/LEO PPP in the global area shorter than that of BDS/GPS PPP, the root mean square (RMS) of the LEO orbit error should be less than 5 cm, 11 cm, 12 cm in the 6×10,12×10,18×10 LEO constellation configuration respectively.