Alternative PNT: What Comes After DME?
Gerhard Berz, Valeriu Vitan, Eurocontrol, Belgium; Luca Saini, Thales Air Systems, Italy; Mike Spanner, NATS, United Kingdom
Location: Regency Ballroom
Date/Time: Friday, Apr. 20, 8:30 a.m.
The development of multi-constellation, multi-frequency GNSS is ongoing, with the aim to enable a robust and reliable navigation and approach service to airspace users. While this will greatly reduce vulnerability to space weather, unintentional interference and constellation weakness, some residual vulnerabilities will remain. In the current, predominantly GPS L1 GNSS environment, aviation has accepted that alternate positioning, navigation and timing capabilities based on terrestrial systems remain necessary. The reversionary navigation capabilities are based primarily on DME/DME, while still providing some residual VOR/DME services. However, DME is being criticized as spectrum inefficient, and aviation-internal and aviation-external pressures to share the DME band with other services are increasing significantly. A key question for the future evolution of Communication, Navigation and Surveillance (CNS) systems is what type of a reversionary capability will be needed in the future (terrestrial or space based), and what performance levels it needs to provide. To answer this question, supported by specific technology options, a project under the SESAR Horizon 2020 Framework (PJ14-03-04) is working on this topic under the title “Long Term A-PNT”.
Long Term A-PNT is a complex, multi-disciplinary topic, with technical and operational aspects going across the CNS domains, and spectrum concerns being an underlying driver. This paper will focus the discussion on aspects related to DME, first by looking at what could be done to improve the current operation of DME, while contrasting it with what could be achieved with completely different alternatives. Possible improvements to current DME include adding more advanced signal processing methods for improved ranging accuracy, reconsidering the introduction of different channel pulse spacings (that have already been standardized), or adding phase modulation to enable data transmission. Alternate options will be subject to demanding criteria, as they will need to fundamentally increase spectrum efficiency while providing performance advantages over current DME. An overview of current research ideas will be given, with an assessment of their prospects considering technical and programmatic aspects.