Alternative Position And Navigation Based On Dme Accumulated Delta Range

A method is analyzed that estimates absolute aircraft position and velocity based on time-series of accumulated delta range measurements from Distance Measuring Equipment (DME) ground transponders. This method provides an Alternative Position and Navigation - but not quite Timing - (APNT) system for use in airplanes as a backup to the Global Navigation Satellite System (GNSS). It performs absolute navigation based on relative-change-in-range measurements. These measurements are provided by nearly continuous radio-navigation carrier phase observables. A Square Root Information Extended Kalman Filter (SRIF) is developed for this method, and a corresponding medium-fidelity truth-model simulation is used to evaluate the filter performance in absolute position observability, filter convergence times, and steady state accuracies for representative scenarios. The results show that a steady state accuracy level below 0.025 nautical miles is achievable, and they reveal the potential usefulness of the proposed method as part of the Federal Aviation Administration's APNT program.