Alternative Position, Navigation and Timing (A-PNT) Using Time Difference of Arrival (TDOA) of Low Earth Orbit (LEO) Signals Of Opportunity (SOOP)

Abstract

As is well-known, signals from Global Navigation Satellite Systems (GNSS) such as the US Global Positioning System (GPS) are used throughout systems that US forces depend on. Yet GPS/GNSS are particularly unreliable in areas of US engagement with enemy forces, where jamming and spoofing would be advantageous to an adversary. We propose a solution that uses a software defined receiver and advanced algorithms to provide Alternative Position, Navigation and Timing (A-PNT) using Time Difference of Arrival (TDOA) of Low Earth Orbit (LEO) Signals Of OPportunity (SOOP). In this mode of using LEO signals, no confidential knowledge of the source signal is necessary. Indeed, no a-priori knowledge of the LEO orbit parameters, nor the time of transmission of the signals is assumed. This system is designed to work standalone or can also be used to complement existing navigation sensors that are typically used in navigation systems, including GNSS and Inertial navigation. Expansion to the usage of multiple LEO constellations will serve to optimize performance and resiliency in an RF challenged environment.