Techniques to Provide Resilient Alternative Positioning, Navigation, and Timing (APNT) Using Automatic Dependent Surveillance - Broadcast (ADS-B) Ground Stations

The United States Federal Aviation Administration (FAA) Alternative Positioning, Navigation, and Timing (APNT) program is examining the use of existing FAA terrestrial infrastructure to provide navigation capable of continuing US National Airspace System (NAS) operations should Global Navigation Satellite System (GNSS) position, navigation, and timing (PNT) services be unavailable. The approximately 700 automatic dependent surveillance broadcast (ADS-B) ground stations in the United States, these ground stations represents a key existing infrastructure that can be leveraged to deliver APNT. However, ADS-B was not designed to provide high accuracy/high integrity navigation services – it was designed to provide surveillance to air traffic control (ATC) automation systems to support the safe separation of aircraft and advisory services to pilots. As a result, ADS-B transmissions do not inherently possess features, such as ranging or integrity, necessary to support APNT navigation requirements. This paper describes and analyzes some possible means for aircraft to use ADS-B ground station signals for precise positioning or ranging to support area navigation (RNAV) and potentially required navigation performance (RNP).