An Improved Estimation Algorithm for User Vertical Protection Level

To accurately apply satellite signal-in-space (SISE) in GNSS, and to rationally estimate user vertical protection level, is the key of ensuring normal application of GNSS and user safety. This paper presents an estimating model of equivalent range error affected by SISE based on its influence characteristic on the user positioning. And according to the VPL integrity theory, uncertainty law of error measurement, a new algorithm of rationally estimating VPL was established.