Examination of GPS/EGNOS integrity in north-eastern Poland

Integrity of positioning is one of the key aspects of satellite based augmentation systems. This paper presents a study carried out in north-eastern Poland, a region which is considered as a border of the operation of the European Geostationary Navigation Overlay Service (EGNOS) system. Detailed analyses concerning operational parameters of EGNOS were done during the 12-hour and 24-hour measurement sessions conducted at a fixed point. The study was focused on the role of ionospheric delays in the integrity model according to the Radio Technical Commission for Aeronautics guidelines. In determination of the accuracy and integrity of positioning, two variants of calculations were adopted: one based on a standard interpolation algorithm determining ionospheric delay by the EGNOS system, and the other based on the Klobuchar model. The research found that the first method is characterised by only slightly better accuracy results, while significant differences were obtained by examining the integrity of positioning. For both variants of the calculation design, the values of protection levels determined for the fixed point are much higher than the positioning accuracy, which meets the integrity requirements of the navigation system.