Estimation of doppler positioning for NavIC system in static and dynamic conditions

Abstract

The primary objective of any navigation system is to provide accurate user position. Navigation with Indian Constellation (NavIC) is an emerging regional satellite navigation system being developed by ISRO, India. The positional accuracy of the NavIC depends upon various parameters based on the application. Doppler shift is one among those parameters which plays an important role in finding the user position in dynamic conditions. The effect of the Doppler shift is more in high dynamic applications like missiles launching, air navigation due to high relative velocity between receiver and satellite. In this Paper, an efficient algorithm is developed to estimate the Doppler positioning using least squares method in static and various dynamic conditions. For this, the experimental data acquired from Indian Regional Navigation Satellite System (IRNSS)-GPS receiver located at low latitude station (Hyderabad: 17.39˚N, 78.31˚E) is used. A trajectory path has been simulated to estimate the user position and its accuracy measures in low and high dynamic conditions. It is noticed that, Doppler shift vary ±1KHz for geosynchronous satellites in static conditions, whereas it is ±40KHz in high dynamics. It is observed the position error is high in high dynamics as compared with low dynamics because of the higher Doppler shifts.