Performance of Current Distance Measuring Equipment and Implications on Alternative Position Navigation and Timing for Aviation

Matt Harris, Tim Murphy, Robert W. Lilley, Robert H. Erikson

Abstract:	his paper discusses some opportunities and challenges related to use of DME as an alternate source of positioning, navigation and timing (PNT), usable in the absence of GNSS services for aviation applications. In the near to medium term, Distance Measuring Equipment (DME) is the obvious solution to the need for a backup to GNSS for aviation applications for the following reasons. DME systems already exist and are standardized. Airborne equipage is near ubiquitous on air transport class airplanes. Furthermore, existing wide deployment of DME ground facilities and a long history of successful service globally all point to potential benefits of DME improvement and continued use. However, the current specified performance of DME systems limits their usefulness as a backup to GNSS. A general investigation into the performance of DME systems is warranted to include: the real performance of currently fielded DME equipment (both ground and airborne) and what modifications could be made in the equipment and/or standards to allow more advantageous use of DME systems as an alternative to GNSS. This paper describes distance measurement data that was collected using current-generation DME avionics in the laboratory and during many hours of flight testing using large air transport airplanes and a high-precision truth reference system. Performance of the current DME system is compared with the existing standards, and opportunities are considered for improvement of the standards so that the achieved accuracy can be exploited without replacement of existing airborne equipment. Similarly, potential improvements to ground-based DME transponders are considered. Several potentially viable alternatives for improving DME utility are identified and discussed. Finally, the paper includes some general discussion of potential future generations of DME equipment and standards.
Published in:	Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012) September 17 - 21, 2012 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	2091 - 2103
Cite this article:	Harris, Matt, Murphy, Tim, Lilley, Robert W., Erikson, Robert H., "Performance of Current Distance Measuring Equipment and Implications on Alternative Position Navigation and Timing for Aviation," Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012), Nashville, TN, September 2012, pp. 2091-2103.
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