Simultaneous Tracking of Orbcomm LEO Satellites and Inertial Navigation System Aiding Using Doppler Measurements

A framework for simultaneously tracking Orbcomm low Earth orbit (LEO) satellites and using Doppler measurements drawn from their signals to aid a vehicle's inertial navigation system (INS) is developed. The developed framework enables a navigating vehicle to exploit ambient Orbcomm LEO satellite signal Doppler measurements to aid its INS in a tightly-coupled fashion in the event global navigation satellite system (GNSS) signals become unusable. An overview of the extended Kalman filter-based simultaneous tracking and navigation (STAN) framework is provided. Experimental results are presented showing an unmanned aerial vehicle (UAV) aiding its INS with Doppler measurements drawn from two Orbcomm LEO satellites, reducing the final position error from 31.7 m to 8.9 m after 30 seconds of GNSS unavailability.