GAGAN - The Indian satellite based augmentation system

Abstract

Global Positioning System (GPS) from the USA, Global Navigation Satellite System (GLONASS) from the Russian Federation and the proposed GALILEO satellite navigation system from Europe are meant for providing position and timing information for a variety of applications. However, for Safety Critical applications the basic constellations cannot meet the requirements in terms of accuracy, integrity and availability. For this purpose, the basic constellations are augmented by an overlay system. Indian Space Research Organization (ISRO), along with Airport Authority of India (AAI) is implementing the Satellite Based Augmentation System (SBAS) for the Indian region. The project called GAGAN (GPS Aided Geo Augmented Navigation) has a full complement of the SBAS inclusive of ground and onboard segment. The first phase of GAGAN is nearing completion. This paper deals with the basic SBAS concept, GAGAN configuration, implementation and the challenges involved. The roadmap towards the final operational phase is also indicated.