Performance analysis of undifferenced and uncombined PPP based on CNES OSB products

In precise point positioning, the fixed ambiguity can significantly improve the positioning accuracy of PPP and accelerate the convergence speed to a certain extent. The quality of phase deviation products directly determines the ambiguity resolution effect, and then affects the positioning performance of PPP-AR. At present, CNES is the only analysis center that publicly provides real-time observable-specific signal bias products (OSB). In order to promote the practical application of RT PPP-AR, it is necessary to evaluate the data quality and PPP-AR positioning performance of real-time OSB products provided by CNES. In this paper, the observation data of 42 MGEX stations from May 1, 2023 (DOY 121) to May 10, 2023 (DOY 130) are selected, and the positioning performance of PPP-AR is analyzed and evaluated after OSB product correction. In terms of OSB product quality, the data availability (DA) of GPS satellite is greater than 94%, that of Galileo satellite is less than 56%, and the standard deviations (STD) of GPS and Galileo satellite are 0.053 and 0.075, 0.031 and 0.044 respectively. After correction by OSB products, the percentage of wide lane (WL) residuals of GPS and Galileo systems exceeds 90% and 83% within 0.25 cycle, and the percentage of narrow lane (NL) residuals of the two systems within 0.25 cycle is 83% and 81% respectively. As far as the positioning performance of PPP-AR is concerned, the positioning errors of GPS+Galileo dynamic PPP-AR in E, N and U directions are 1.45 cm, 1.51 cm and 4.16cm, respectively, and the ambiguity fixing rate is about 97%. Compared with PPP, the convergence time of PPP-AR corrected by OSB products can be shortened by more than 59%. However, due to the lack of phase deviation, there is a phenomenon of re-convergence in the positioning process. In this paper, Grey model is used to predict OSB data, which has certain reliability and significantly improves the situation of re-convergence.