SBAS avionics compared to GBAS on-board equipment

Global Navigation Satellite System (GNSS) has become an integral part of air navigation. Delay of the GNSS signal in ionospheric layer is one of the most serious problems in using GNSS. Not only accuracy but also the safety is very important in air navigation, and for that reason the augmentation of basic GNSS is used to meet higher requirements of aviation industry. This paper discusses Satellite-Based Augmentation System (SBAS) avionics with special emphasis on correction of signal delay in ionospheric layer as one of the most significant error fixes and compares it with other GNSS based on-board equipment - with basic GNSS (GPS) in terms of accuracy and with Ground-Based Augmentation System (GBAS) generally. This article should therefore show reader the differences between the methods of calculating ionospheric corrections by SBAS and GBAS and explain the reasons of these methods, taking into account the area of intended use of both systems.