Ishita Ganjoo
ISRO Satellite Centre
India
Title: Smoothened Absolute Kinematic Position Estimation of LEO satellites using GPS Observables
Biography
Biography: Ishita Ganjoo
Abstract
In this paper, the objective is to use the navigation signals (pseudorange and carrier phase measurements) from GPS satellites to kinematically estimate the precise absolute position of a Low Earth Orbit (LEO) satellite and their receiver clock biases. GPS observables can estimate the precise position of a satellite in near real time. The GPS satellite navigation and observables file is downloaded for the starting epoch of 01-01-2016 00:00 UT. The observables are then generated for a LEO satellite at an altitude of 901.4 km. The absolute position is estimated using pseudorange measurements. The worst case accuracies obtained are [5.68 8.04 6.17] m in ECEF frame which are observed when the dilution of precision (DOP) value is high due to poor geometry of the visible GPS constellation with respect to the LEO satellite. This estimated absolute position is smoothened with the time-differenced carrier phase measurements. The Kalman filter gains are computed in near real time. The worst case smoothened accuracies obtained are [2.24 2.60 2.6982] m in ECEF frame. This has shown improved estimated absolute position.