UDRE estimation approach based on satellite surveillance dilution of precision

Satellite based augmentation system (SBAS) provides user differential range error (UDRE) which guarantees satellite ephemeris and clock correction accuracies to the users to enhance their integrity. A method of calculating UDRE only used in the master station was introduced, then a concept of satellite surveillance dilution of precision (SSDOP) was proposed to reflect the effect of changing the reference stations' distribution on the satellite ephemeris and clock correction accuracies. A mathematical equation was deduced from the SSDOP and UDRE expressions, and from the view of the equation the UDRE was infected by SSDOP and restriction factor which could be replaced by, 0.7438, its statistic average value. The equation based upon SSDOP to estimate UDRE was established. The simulation results show that the estimation value of UDRE based on SSDOP can reflect the performance of the current UDRE and its accuracy is less than 0.8 m. This approach can be used as an alternative method to calculate the UDRE when the user can't receive the integrity information broadcasted by SBAS.