Global positioning with wide area differential technology

The concept of accurate global positioning using wide area differential technology has attracted worldwide attention. This paper addresses the issues, as relevant to Indian context, and presents a system conceived nationally to serve the interests of users countrywide. The system consists of nine different differential GPS monitoring sites and two master control stations (MCS), one working as 100% redundant to other. The MCS receives data from these sites and transfers the processed data to a ground Earth station for uplinking it to a satellite. Sites have been chosen by study of the satellite visibility charts including the availability and reliability of GPS signals over Indian land mass, scintillation effects etc., and determining the common view satellites between adjacent sites, and developing a network to provide a unified coverage with maximum number of visible satellites throughout the country. The Indian approach for the development of wide area differential augmentation technology has been presented in this paper. The implementation aspects are also discussed and preliminary results of the studies presented.