Techniques for High Accuracy User Position Estimation Using NavIC Constellation

The User Equivalent Range Error (UERE) accuracy of NavIC satellites performs better than 20 m based on operational orbit determination (OD) from sixteen IRIMS one-way range measurements, and two-way range measurements using four IRCDR stations. These stations are geographically located within India and a few outside. The NavIC-OD is carried-out by applying a weighted least square batch estimation algorithm.The present work performs a study to estimate the position instantaneously using trilateration by extending network of tracking stations with a sufficiently Long Baseline Tracking Stations (LBTS) in such a way that minimum four number of LBTS will have simultaneous access to any NavIC satellite. The Gauss-Newton Method is employed to estimate the position instantaneously. Further, LBTS stations tracking data are simulated to enhance the NavIC broadcast ephemeris by carrying out real time OD with Extended Kalman Filter (EKF).