Analysis of differential code biases and inter-system biases for GPS and NavIC satellite constellations

Multi Global Navigation Satellite System (GNSS) plays an essential role in navigation and geodesy fields for positioning, Navigation, and Timing (PNT) services. The predominant challenge of multi-GNSS is hardware bias errors such as Differential code Bias (DCB) and Inter System Biases (ISB). The estimation of DCB and ISB are essential for analyzing the GNSS system performance to improve the positional accuracy. Navigation with the Indian Constellation (NavIC) system consists of the entire constellation of seven Geo-Stationary satellites to cater to Position Navigation Time (PNT) services over India and adjacent areas. In this paper, the relation between DCB and ISB of Global Positioning System (GPS) and NavIC systems is investigated using two ground-based NovAtel GPS and three Accords NavIC Receivers data (January to April 2019) at Koneru Lakshamaiah Education Foundation (K.L. Deemed to University), Guntur, India (16.47°N, 80.61°E). The correlation results indicate that NavIC GSO satellites are more stable than GEO satellites from DCB and ISB analysis due to low elevation angles and multipath effects. A systematic bias error is observed between NavIC and GPS satellite systems from ISB and DCB results. The current research work outcome would be beneficial for modeling GNSS ionospheric Total Electron Content (TEC) for high precision multi-constellation and multi-frequency GNSS systems.