Robust DME Carrier Phase Tracking under Flight Dynamics

Kuangmin Li and Wouter Pelgrum

Abstract:	Next Generation Air Transportation System (NextGen), a comprehensive overhaul of US air traffic, relies heavily on high-performance Positioning Navigation and Timing (PNT). Currently, the Global Navigation Satellite Systems (GNSS) is the sole provider of this high-performance PNT solution. To mitigate the vulnerability of GNSS to events such as RF interference and solar activities, an alternative PNT (APNT) service is required. A favorable APNT candidate is the Distance Measuring Equipment (DME) system as it does not share common failure mode with GNSS and it leverages an extensive world-wide infrastructure. However, current (legacy) DME performance is not sufficient to meet the most stringent NextGen PNT requirements. DME-Next is proposed as an enhanced DME architecture to meet even the most stringent NextGen PNT requirements [5]. The key enabling technology of DME-Next is DME carrier phase tracking. To be most effective, continuous and uninterrupted carrier phase measurements is required. This paper introduces two methods to significantly improve DME carrier phase tracking robustness. The combination of coherent integration and RF filter optimization provides a total of 14 dB SNR improvement for carrier phase tracking. Flight test results demonstrate excellent tracking performance up to 90 km distance from a low-power DME transponder, with more than 20dB SNR margin. Turning maneuvers can potentially obstruct the DME signal path causing temporarily loss-of-lock of the DME carrier Pphase tracking. Detailed airborne antenna measurements are presented in this paper, indicating the azimuth sectors that could impose carrier phase tracking challenges during banking. Flight tests demonstrate excellent carrier phase tracking robustness, even during extreme aircraft banking.
Published in:	Proceedings of the 2013 International Technical Meeting of The Institute of Navigation January 29 - 27, 2013 Catamaran Resort Hotel San Diego, California
Pages:	696 - 708
Cite this article:	Li, Kuangmin, Pelgrum, Wouter, "Robust DME Carrier Phase Tracking under Flight Dynamics," Proceedings of the 2013 International Technical Meeting of The Institute of Navigation, San Diego, California, January 2013, pp. 696-708.
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