Estimation of Differential Code Bias of IRNSS Satellites using Global Ionosphere Map

Abstract

AbstractIRNSS (Indian Regional Navigation Satellite System) is an independent satellite based regional navigation system, developed by India, with an aim to provide accurate positioning and timing services to user in India as well as 1500 km away from its boundary. IRNSS is a constellation of seven satellites, three satellites are orbiting in a GEO (Geostationary orbit) and remaining four satellites are in GSO (Geosynchronous orbit).IRNSS provides navigation services on two frequencies i.e. L5 (1176.45 ± 12 MHz) and S band (2492.028 ± 8.25 MHz). The measurements from dual frequency IRNSS/NavIC (Navigation with Indian Constellation) receiver are affected by instrument bias of satellite and receiver. Differential Code Bias (DCB) is the hardware bias between two GNSS code at same or different frequency. DCB can't be ignored for both precise positioning as well as for precise TEC estimation. Currently there are limited numbers of IRNSS satellites, so it is difficult to build an independent Ionospheric model for the precise estimation of DCB of IRNSS satellites.There are several Ionospheric Associated Analysis centers (IAAC), providing the DCB (Differential Code Bias) of different GNSS satellites (GPS, GLONASS etc.) along with the Global Ionospheric Map (GIM) on routine basis. Knowledge of DCB is currently unavailable for newly developed constellations like IRNSS, due to the limited number of satellites and monitoring stations. In this paper Global Ionospheric Map (GIM) published by IGS (International GNSS services) is used as a reference for the estimation of DCB of IRNSS satellites. More than 60 days' observation data of IRNSS Range integrity and monitoring station (IRIMS) were analysed and DCB of each day was computed with the stability of up‐to ∼1 ns for all IRNSS satellites in constellation.