Velocity and Acceleration of NavIC Satellites using Broadcast Ephemeris

Bidyut B Gogoi,A Kartik,Nirmala S,Akhilesh Kumar

doi:10.33889/ijmems.2018.3.3-021

Abstract

The current manuscript describes a methodology to derive velocity and acceleration of NavIC satellites from the broadcast ephemeris. A fourth-order central differencing formula is used to derive NavIC satellites’ Earth-Centred-Earth-Fixed (ECEF) velocity from the ECEF positions that are calculated using the standard IRNSS-SIS-ICD algorithm. The proposed methodology is quite simpler and straight forward than the conventional rotation matrix method and therefore it can be a very good alternative to the existing approaches. The same differencing formula has been further implemented to derive the ECEF acceleration form the ECEF velocities. Results obtained demonstrated that the satellites’ ECEF velocity can be approximated upto an accuracy of 0.6 mm/s while the ECEF acceleration can be of the further accuracy of within 0.06 mm/sec2 in each axis.

Highlights

Indian Space Research Organization (ISRO) is in the process of deploying an independent regional navigational system with an operational name NavIC (Navigation with Indian constellation) (Gogoi et al, 2017)
The objective of the current work is to provide a methodology wherein NavIC can be utilized for precise velocity and acceleration determination of a number of applications like automobile brake system testing, athlete monitoring, airborne gravimetry (Yun and Zheren, 2003), moving base gravimetry (Jekeli, 2016) and other varied applications
The work in this manuscript presented a simple methodology of deriving satellite velocity and acceleration from the broadcast ephemeris

Summary

Introduction

Indian Space Research Organization (ISRO) is in the process of deploying an independent regional navigational system with an operational name NavIC (Navigation with Indian constellation) (Gogoi et al, 2017). The present constellation of NavIC comprises of seven satellites, 3 GEO satellites located at 32.5o E, 83o E and 129.5o E and 4 GSO satellites with their longitude crossings 55o E and 111.75o E (two in each plane) (IRNSS SIS ICD, 2011). All these seven satellites are fully operational and currently NavIC provides a position accuracy better than 20 meters over India and a region extending about 1500 km around India. The navigation system of NavIC is generally known as Indian Regional Navigation Satellite System (IRNSS). The velocities and accelerations of atleast 4 IRNSS satellites must be determined and taken as known values to find the velocity and acceleration of a NavIC user

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Results

Conclusion