Message Design for a Robust Time Signal using Distance Measuring Equipment (DME) Pulse Pair Position Modulated (PPPM) Pseudo lite

The Federal Aviation Administration (FAA) Alternative Position Navigation and Timing (APNT) program developed several possibilities for improving distance measuring equipment (DME) such as DME pseudolite (PL) systems to provide data and passive ranging in addition to traditional DME operations. These enhanced DME (eDME) were designed to serve as an operational back up to GPS/GNSS, particularly to support future airspace and Next Generation Air Transportation System (NextGen) operations. While eDME concepts are not part of the current upgrades to the US DME system, there is continued interested in the ideas as they can support other airspace needs and help meet federal directives to increase the resiliency of Positioning, Navigation, and Timing (PNT) services [1].