Towards standardisation – satellite-independent navigation in the Baltic Sea

Between 2017 and 2021, DLR and project collaborators developed and established the world's first large-scale testbed for the radio-based R-Mode system. "This first step towards establishing a maritime backup system in the Baltic Sea region has demonstrated that R-Mode technology works in practice as an alternative terrestrial navigation system, enabling ship positioning even without satellite-based systems," says Anke Kaysser-Pyzalla, Chair of the DLR Executive Board. "With this, DLR is not only making an important contribution to maritime safety, but ultimately also supporting economic performance."

R-Mode – a cost-effective backup to satellite navigation systems

The DLR Institute of Communications and Navigation is working on technologies to detect and suppress interference with global satellite navigation systems, ensuring the availability and reliability of navigation data using alternative sensors and systems. Initiated by the Federal Waterways and Shipping Administration (WSV), DLR researchers developed the alternative Ranging Mode (R-Mode) terrestrial radio navigation system. R-Mode uses existing infrastructure from national maritime organisations to provide radio services in the medium-wave and very high-frequency ranges, offering a cost-effective supplementary navigation service. Over the past seven years, a test area comprising eight R-Mode transmitters has been established over approximately 800 kilometres between Heligoland and Stockholm.

In addition to DLR, other research institutions, maritime authorities and industrial companies are using the test area to help establish and validate the R-Mode technology and develop prototypes of R-Mode-based receivers and applications.

Expansion of the R-Mode test field in the Baltic Sea region

The ORMOBASS project, launched in 2023, is currently expanding the test area to cover the Baltic Sea region between Sweden, Finland and Estonia – a region that frequently reports navigation system disruptions. In 2024, researchers analysed the existing medium-wave signal stations (radio beacons) in the region and, together with the existing transmitters in the test area, developed a concept for expansion. This plan, which encompasses the system's basic functions, will be implemented in 2025 and 2026. The goal is to develop all essential functions of the R-Mode system for both frequency bands – medium and very high frequency – by 2026, making them available to the relevant maritime authorities for operation. In addition to project management, DLR is responsible for the development of R-Mode receiver technology, system design, testing and standardisation.

Standardisation – the path to system approval

For ships to use the R-Mode system during their passage between two ports, transmitters must offer a uniform R-Mode service, and on-board receivers must be approved for maritime navigation. Both of these requirements depend on the standardisation of R-Mode by various organisations. For the medium-wave part of the R-Mode system, the concept developed in the ORMOBASS project – along with results from previous projects in the Baltic Sea region and from DLR's Transport and Security programmes – were successfully incorporated into the new IALA (International Organisation for Marine Aids to Navigation) guideline on medium-wave R-Mode signal characteristics and navigation messaging. Experiences from Canada and South Korea were also taken into account. The result of this five-year effort, IALA Guideline 1187, has been available to all interested parties who wish to use medium-wave R-Mode signals since early 2025.

In the ORMOBASS project, researchers have now begun implementing this guideline in the Baltic Sea region. From early 2026, the standardised signals will be available in the area between Germany, Finland and Estonia.

Related links