Telespazio UK Head of Navigation, Martin Bransby, presented 'VDES - R-Mode Advanced User Technologies for Alternative PNT', during session B2: Marine Applications, and Search and Rescue, on Wednesday 13 September.
Global Navigation Satellite Systems (GNSS) have become the primary marine 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. Maritime trials, and trial in other domains, have demonstrated that degraded GNSS produce hazardously misleading information and erroneous vessel positions without an alarm being raised. 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.
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.
Having a System-of-Systems approach requires that systems other than GNSS be utilised to provide resiliency. One such system is the Very High Frequency Data Exchange System (VDES). VDES is a new maritime radio communication system in development by the international maritime community, with the principal objectives, to:
- Safeguard existing Automatic Identification System (AIS) core functions, such as ship-to-shore and ship-to-ship position reporting, preventing future AIS overload
- Enhance 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 relatively 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.
This paper described the investigation, consolidation and development of 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.