A terrestrial positioning and timing system (TPTS)

This paper investigates the concepts of a Terrestrial Position and Timing System (TPTS) that could be used within the National Airspace System (NAS) in the event of a GPS outage to provide a positioning, navigation, and timing (PNT) service to aviation users. Concepts for a TPTS are presented for an L-band based system to be integrated/compatible with the distance measuring equipment (DME) system. The TPTS will be based upon a CDMA and TDMA signal structure. Three main operational modes are presented for a TPTS: 1) Autonomous Broadcast Mode, and 2) Active Interrogation/Response (IR/XP) Mode, and 3) a Hybrid solution. With a fully operational TPTS, an active TPTS aviation user could calculate a position, velocity, and time (PVT) solution from a single TPTS Site. The passive TPTS aviation user could calculate a PVT solution using the signals broadcast by two TPTS ground sites. With three TPTS sites in view, the passive TPTS aviation user equipment can calculate an “all-in-view” PVT solution using a subset of the signals transmitted from the TPTS ground sites. Additional studies will be needed to further explore the concepts of a TPTS for refinement, investigate compatibility with current systems, and validate these concepts, parameters, and techniques.