The User Domain Integrity Assessment Technique

Abstract

This paper presents a study performed for the detailed analysis of user domain and pseudorange integrity on Satellite Based Augmentation Systems. Experimental data of EGNOS pre-operational service was used for some specific tests, aiming at identifying for instance the good reaction of the EGNOS check-set subsystem and the way pseudorange errors are translated into the user domain. From this analysis, a new technique for User Domain Integrity Assessment (UDIA) was developed. With the UDIA technique, the integrity is checked for all possible geometries from 4 to all satellites in view from a network of stations. When no MI is found (from a wide and sufficiently dense stations network), it can be assured that the system is safe, and it becomes the best experimental guarantee at the User Domain Level. If a NMI/MI appears from any geometry of satellites from the stations in the network, thence a search algorithm is applied to identify the satellite, or combinations of satellites, responsible of such NMI/MIs (i.e., their exclusion leads to the disappearance of the NMI/MIs). After identifying such satellites, the reaction of the EGNOS Check Set (CS) is evaluated by checking if they were set as DU or NM within a predefined time interval after the NMI/MI is detected.