An Efficient New Method on Accurately Estimating Galileo VPL

s: The future GALILEO system will use multi-frequency data to process, which may eliminate preferably the influence of ionosphere relay. So the VPL estimation is mainly to consider how to efficiently use the satellite Signal-InSpace (SISE). To efficiently utilize SISE in GNSS and to rationally estimate the user Vertical Protection Level, it is the key to ensure normal application of GNSS and user’s safety. For the investigation requirement of GALILEO VPL algorithm. Based on the character which SISE influences on users’ positioning, this paper provides an estimating model of equivalent range error of SISE which influences users efficiently. On the bases of the integrity theory of VPL and the principle of synthetizing and assessing the uncertainty of measurement errors, it also gives a new algorithm to estimate VPL rationally to provide references for the development and the application of the integrity theories of GNSS.