Performance analysis of Navigation with Indian Constellation satellites

Abstract

Navigation satellite system plays a major role in finding the position of a user. Similar to GPS, Navigation with Indian Constellation (NavIC) is developed by India to cater the country needs. The NavIC Standard Positioning Service User Receiver (UR) placed at ACS College of Engineering (12.8914° N, 77.4657° E), Bangalore for field trial and data collection. The accuracy of the navigation system is influenced by several kinds of error factors, among which the signal delay influenced by the ionosphere is the greatest error factor. The delay in signal causes error in satellite signal range data and it is called range error. This range error can reduce the accuracy of user position. Hence estimation of range error is very essential. In order to give the appropriate user position, estimation of Total Electron Content (TEC) is vital, which indicates ionospheric error (signal delay). In this paper, VTEC of ionosphere is estimated for the entire day and over a month. The observation data required for estimation of TEC is collected from NavIC SPS receiver located at ACS College of Engineering Station (ACSCES), Bangalore. By using estimated VTEC value, it is possible to correct range error which results in accurate position estimation. NavIC TEC derived using pseudo range at ACSCES is compared with GPS TEC and IRI-2016 TEC which belongs to IISC Station. From the comparison, it is observed that, the maximum NavIC TEC is 43.0552 TECU and maximum GPS TEC is 44.6131 TECU and maximum IRI-2016 TEC is 18.6 TECU. RMSE between GPS and NavIC TEC is 5.486 TECU, correlation coefficient is 0.9748 and average difference is 5.2306 TECU. Similarly, RMSE between NavIC and IRI-2016 TEC is 9.9899 TECU, correlation coefficient is 0.93 and average difference is 9.421 TECU. From the collected data, C/No are plotted for each satellite. From the C/No plots, it is observed that, C/No is good i.e. above 40 dB-Hz. Based on the results, it is evident that, NavIC is suitable for navigational applications in Indian region.