Abstract: In view of the fact that BDS-3 broadcasting B1I/B3I/B1C/B2a signals and the comparative analysis of PPP positioning performance for the current B1I+B3I and B1C+B2a data is still relatively scarce.In this paper,based on the establishment of the BDS-3 undifferenced and uncombined PPP positioning model,an implementation flowchart of integer ambiguity fixed algorithm for BDS-3 undifferenced and uncombined PPP is decuced in detail.The BDS-3 undifferenced and uncombined PPP positioning analysis software (short as UDUC_PPP)using C/C++programming language based on Visual Studio 2022 development platform is designed and developed applied to compare and analyze the positioning performance of BDS-3 undifferenced and uncombined PPP for B1I+B3I and B1C+B2a data.Supported by BDS-3 B1I/B3I/B1C/B2a signals from fourteen representative stations with globally distributed in the MGEX experimental network for 060 d for 24 hours consecutive observation data in 2024 are selected for the positioning performance analysis,the results show that the convergence time and the positioning accuracy of BDS-3 undifferenced and uncombined PPP fixed resolution are better than the float resolution positioning for not only B1I+B3I data but also B1C+B2a data,in which the integer ambiguity resolution success rate is 92.5%above after the positioning convergence for BDS-3 undifferenced and uncombined PPP for both of B1I+B3I and B1C+B2a data,meanwhile the positioning accuracy of BDS-3 undifferenced and uncombined PPP fixed resolution is better than 0.9 cm in the horizontal-RMSE and 2.3 cm in the point-RMSE respectively.For both float resolution and fixed resolution,BDS-3 undifferenced and uncombined PPP positioning in terms of convergence time for B1C+B2a data is better than for B1I+B3I data,which the positioning accuracy is basically comparable.

Key words: BeiDou-3 Satellite Navigation System, precise point positioning, undifferenced and uncombined model, integer ambiguity resolution, dual-frequency data