The Future Role of a “Standalone” Distance Measuring Equipment (DME) in the United States National Airspace System (NAS)

E. Etienne, V. Hinton, S. Frodge, R. Achanta

Abstract:	DME service volumes are currently described as being identical to the service volume of the VOR with which they are co-located – and the VOR service volume is described as an “upside-down wedding cake” which typically expands in radius at the system imposed transitions between terminal, low en-route, and high en-route airspace – hardly following the laws of physics. It was quickly recognized that to most effectively utilize DMEs to support Area Navigation (RNAV), a change to the DME service volume would be required. However, these service volumes also allowed for some DMEs to broadcast at lower power levels (Note: a typical DME output is 1000 watts) and to officially serve only terminal and low en-route airspace. While the International Civil Aviation Organization (ICAO) Annex 10 recommendation for co-channel DME protection limits is 8 dB, the FAA required this protection limit to be 11 dB. This is because the U.S. National Aviation Standard for the VOR/DME/TACAN Systems, Order 9840.1, revised interference protection ratios for DME/TACAN systems in 1982 to account for peak power deterioration in DME transponders. In order to account for this decrease in power, an additional 3 dB of protection was added to the interference protection ratio. The FAA Navigation Program Engineering, working with FAA Spectrum Engineering Services and William J. Hughes Technical Center has conducted a series of flight tests and engineering analysis intended to demonstrate that, for the current generation of DME transponders, removing the additional 3 dB of interference protection for peak power deterioration will continue to provide ample interference protection for DME systems operating in the National Airspace System (NAS). Testing was conducted on eight different DME antennas. These antennas were evaluated and compared to their individual performance. These antennas consist of: DB Systems LPTA, DB Systems 510A, and DB Systems 5100A (Omni), DB Systems 5100A-BD (bidirectional), DB Systems 5100A-D (directional), ITT/WILCOX RTA-2 (TACAN), Cardion, and the Montek. This paper focuses on the flight test setup, procedure and engineering analysis. The results of the data collected and other necessary activities hopefully will lead to the procurement and installation of stand-alone DMEs to optimize a performance-based (PBN) NAS architecture.
Published in:	Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013) September 16 - 20, 2013 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	251 - 262
Cite this article:	Etienne, E., Hinton, V., Frodge, S., Achanta, R., "The Future Role of a “Standalone” Distance Measuring Equipment (DME) in the United States National Airspace System (NAS)," Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013), Nashville, TN, September 2013, pp. 251-262.
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