Flight Test Evaluation of Enhanced DME(eDME) Performance Enhancements

Kuangmin Li and Wouter Pelgrum

Abstract:	Next Generation Air Transportation System (NextGen), a comprehensive modernization of US air traffic, heavily relies on high performance Positioning Navigation and Timing (PNT). Global Navigation Satellite Systems (GNSS), in combination with Space-Based Augmentation Systems (SBAS) and Ground-Based Augmentation Systems (GBAS) are instrumental in the provision of the required PNT performance. To mitigate the vulnerability of GNSS to, for example, RFI interference, significant solar activities, or constellation failures, a backup PNT solution is needed. Such GNSS-independent backup is referred to as APNT, Alternative Positioning Navigation and Timing. This paper focuses on DME-DME (Distance Measuring Equipment) as an APNT candidate, and potential ranging performance enhancements that can be achieved with a modernized DME system. Pseudorange, enabled by beat signal broadcast, provides absolute range measurement, but suffers from significant measurement noise, and it is susceptible to multipath. Carrier phase, on the other hand, is a cm-level accurate displacement measurement, it has minimal noise, and it is not susceptible to multipath. The combination of DME carrier phase with DME pseudorange allows for various methods that increase the accuracy and integrity of the Positioning, Velocity, and Timing (PVT) solution. Carrier Smoothed Pseudorange (CSP) significantly reduces pseudorange noise and multipath. Next, variations in Pseudorange Minus Carrier (PMC) are used to bound the potential pseudorange bias. Finally, the Pseudorange Noise MultiPath (PNMP) algorithm combines CSP and PMC to achieve meter-level ranging accuracy with integrity, which is demonstrated using recent flight-test results.
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:	803 - 811
Cite this article:	Li, Kuangmin, Pelgrum, Wouter, "Flight Test Evaluation of Enhanced DME(eDME) Performance Enhancements," Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012), Nashville, TN, September 2012, pp. 803-811.
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