Analysis of earth's coverage of IRNSS and GPS augmented irnss

摘要

Global Positioning System (GPS) is a satellite based navigation system developed and declared operational by the U.S department of defense in the year 1995. It provides position, velocity and time everywhere, on or near the surface of the earth. To achieve nation's security different countries are developing regional navigation satellite systems. In this context India also has developed its regional navigation satellite system called as Indian Regional Navigation Satellite System (IRNSS) with a constellation of seven satellites. The IRNSS is expected to provide positional accuracy of 10 m over Indian landmass and 20 m, over Indian Ocean. IRNSS is featured with highly accurate position, velocity and timing information for authorized users. Studying the satellite coverage area is very essential because it is an important parameter for the analysis of user positioning. In this paper, an algorithm to estimate coverage area of GPS and IRNSS is explained. Using this algorithm, earth's surface coverage of IRNSS 5 and 7 satellite vehicles (SVs) are investigated. The best and worst cases of IRNSS 5 and 7 SV's constellations are analyzed. It is observed that in the worst case the coverage is reduced to a large extent. Subsequently, IRNSS is augmented with GPS and the earth's coverage is estimated. Comparative analysis of IRNSS, GPS and IRNSS augmented with GPS is also performed in terms of surface coverage. The augmentation has caused improvement in the specified performance parameter.