Session A6b: Marine Applications and Search and Rescue

VDES R-Mode Advanced User Technologies for Alternative PNT (VAUTAP) final Developments
Martin Bransby, Tim Whitworth, Pekka Peltola, Telespazio UK; Anders Bjørnevik, Kongsberg
Date/Time: Friday, Sep. 20, 3:42 p.m.

Global Navigation Satellite Systems (GNSS) have become the primary maritime aid-to-navigation and source of Position, Navigation and Timing (PNT) information. Yet, all GNSS are vulnerable to natural interference, deliberate and accidental jamming, and spoofing. Trials have demonstrated that degraded GNSS produce hazardously misleading information and erroneous vessel positions without an alarm being raised by the vessels’ systems. Notwithstanding these vulnerabilities, GNSS have poor coverage at higher latitudes, which is clearly a weakness when vessels wish to operate in regions such as along the Northern Sea Route between Europe and East Asia.
As ships’ systems become increasingly digital, with the introduction of a wide range of supporting services and the emergence of autonomous vessels, PNT accuracy, integrity, continuity, and availability become increasingly critical and so these vulnerabilities pose problems.
Projects have shown that a System-of-Systems approach to the provision of PNT for maritime and other critical infrastructure is preferable to provide resiliency. National Governments, Inter-Governmental Organisations and Multi-National bodies now recognise this System-of-Systems approach and are now looking to implement various systems and as such, bodies are making technical developments.
One such system is the Very High Frequency Data Exchange System (VDES). VDES is a chiefly, terrestrial based maritime radio communication system in development by the international maritime community, with the principal objectives of:
• Safeguard existing Automatic Identification System (AIS) core functions, such as ship-to-shore and ship-to-ship position reporting, preventing future AIS overload; and,
• Enhancing maritime communication applications, based on robust and efficient digital data transmission with wider bandwidth than the AIS.
However, at the same time, the international maritime community has been investigating the potential use of these VDES communication signals, transmitted from shore-based stations, for positioning—a concept commonly referred to as “ranging mode,” or R-Mode.
VDES R-Mode is still at a low Technology Readiness Level and much of the standardisation required for such System-of-Systems components are not yet in place, giving developers the opportunity to develop better waveforms, techniques, components, and concepts to provide truly resilient PNT.
The VAUTAP project has so far investigated, consolidated, and developed new algorithms, waveforms, software, and hardware, to evolve VDES R-Mode closer to an operational and viable component of a resilient PNT System-of-Systems. Some of these activities are:
• In-field capture and positioning demonstration.
• Design of new signals, taking advantage of the Offset Quadrature Phase-shift Keying (OQPSK) symbol constellation.
• Meta signal design, taking advantage of the lower and upper VDES bands.
• Differential Positioning, to provide users with corrections.
• Multi-Epoch Doppler Positioning simulations for LEO satellites.
This paper will provide an update on the activities undertaken so far and will look to provide conclusions of all technical developments and aspects post the testing campaign (to be conducted by the VAUTAP consortium in Spring 2024).