Research On Key Technologies Of BDS/GPS Precise Point Positioning

Precise point positioning(PPP)is widely used in various fields because of the advantages of high accuracy of single station.However,due to the difficulty of fixing ambiguity,floating point solution is mainly used,convergence time is slow,and positioning precision is difficult to achieve high accuracy in a short time.Therefore,based on this problem,this paper studies the BDS/GPS combined precise single point positioning.The main contents are as follows:(1)Aiming at the problem that TurboEdit is easy to fail in detecting small and insensitive cycle slips,this paper proposes a cycle slips detection method which takes into account the correlation of the ionospheric variations of epochs before and after the wide lane combination fuzziness.The simulation results show that this method can detect small cycle slips,insensitive cycle slips and large cycle slips accurately.(2)The ambiguity fixing algorithm of integer clock difference method is studied,GAMP is redeveloped,and ADOP value ambiguity fixing checking condition is introduced to realize the ambiguity fixing function.The positioning results of various ambiguity fixing strategies are compared and analyzed,and the optimal ambiguity fixing strategy based on the least squares partial ambiguity fixing of reference stars is determined.Experiments show that the convergence time of GPS fixed solution in E,N and U directions is shortened by 9.0%,6.3%,9.3% and the positioning accuracy is improved by 29.2%,10.8% and 5.1% compared with floating solution.(3)The effect of BDS/GPS integrated positioning and the influence of BDS on GPS ambiguity fixing are studied.The experimental results show that the BDS/GPS fixed point solution is better than the BDS/GPS floating point solution.The combined positioning has no significant improvement on the accuracy of GPS positioning.The convergence time of the fixed solution of BDS/GPS is reduced by 9.1%,2.4% and 3.9% in the E,N and U directions,respectively,compared with the fixed solution of GPS.(4)The data integrity rate,multipath error and cycle slip ratio of B1 C and B2 a new signals of BDS-3 are studied,and the quality of observation data is analyzed.The orbit determination experiment of three-day arc section is designed,and the precision and frequency stability of BDS-3 precision track and clock difference overlapping arc section are compared and analyzed.The 1D RMS of track overlapping arc section is better than 20cm;the radial radius is better than 5cm;the STD and RMS of clock difference overlapping arc section are better than 0.5ns;the frequency stability of BDS-3 clock difference is improved by 25.9%,8.3% and 14.8% respectively compared with BDS-2 system.(5)The positioning effect of BDS-3 is studied.The combination of BDS-3 and BDS-2/GPS is helpful to improve the positioning effect.In the three directions of E,N and U,the positioning effect is increased by 38.89%,11.39%,28.53% respectively.