Article

Navigation alternative in the event of GNSS failure due to jamming or spoofing


by TRENZ GmbH - published on 7 April 2025 1383 -

Credit: DLR - German Space Agency

R-Mode – Navigation Safety Without Satellites: A Terrestrial Backup for Commercial Shipping.

What happens when GNSS fails? In maritime navigation, this isn’t a hypothetical scenario – it’s a growing risk. Spoofing, jamming, and GNSS outages are increasing, especially in the Baltic Sea region. A failure can cripple navigation systems – with potentially serious consequences.

The answer: R-Mode – a terrestrial backup system that operates independently of satellites. Developed for real-world maritime use. Tested in the Baltic. Ready for the next phase.

Satellite-based navigation via GPS, Galileo, or GLONASS has become an essential part of modern maritime operations. But what happens in the case of deliberate interference (jamming), spoofing, or system failures? For maritime professionals such as harbor pilots, VTS operators, and bridge crews, the failure of satellite navigation systems can have severe consequences—particularly in congested traffic situations, during port approaches, or in narrow shipping lanes. This is exactly where R-Mode (Ranging Mode) comes into play as a terrestrial backup navigation system.

What Is R-Mode?

R-Mode is a radio-based navigation system that utilizes existing maritime radio services—primarily medium frequency (MF) and very high frequency (VHF) transmissions. It determines a vessel's position through the analysis of the signal travel time of continuously transmitted radio signals, applying the principle of hyperbolic navigation (similar to LORAN-C).

Controlled modulations are overlaid onto existing transmission systems, such as DGPS, DGNSS, or NAVTEX stations. Special R-Mode receivers on board analyze signal phases or time differences from multiple transmitters to calculate a two-dimensional position, typically accurate to within 10–20 meters—entirely independent of satellite signals.

Pilot Projects and Standardization

Since 2017, the German Aerospace Center (DLR) has been operating an R-Mode testbed in the southern Baltic Sea in cooperation with European partners. This testbed currently consists of eight transmitters located between Helgoland and Stockholm. Based on a new multilateral frequency agreement, the system is expected to be significantly expanded by 2026. The goal is to establish a standardized, interoperable R-Mode infrastructure across Germany, Poland, Sweden, Finland, and Estonia, with internationally harmonized signal structures.
R-Mode station. Credit: DLR - German Space Agency
R-Mode station. Credit: DLR - German Space Agency
R-Mode station. Credit: DLR - German Space Agency
R-Mode station. Credit: DLR - German Space Agency

Technical Background and Advantages

  • Frequency ranges: Mainly MF (283.5–325 kHz), selectively VHF.
  • Positioning method: Time-of-arrival and phase-difference analysis of signals.
  • Resilience: Independent of GNSS; robust against jamming and spoofing.
  • Cost efficiency: Reuse of existing coastal radio infrastructure.
  • Availability: Particularly relevant for coastal areas and high-traffic maritime corridors.
R-Mode supports the IMO and IALA e-Navigation strategies aimed at improving the resilience of Positioning, Navigation, and Timing (PNT) services. Looking forward, R-Mode is also expected to play a role in multi-sensor data fusion as part of integrated bridge systems.

Outlook

For pilots, navigational officers, and port authorities, R-Mode represents a strategically important building block for maintaining navigational capabilities in the event of GNSS failure. The planned operational readiness of the expanded Baltic testbed by 2026 marks a major milestone toward establishing a satellite-independent, resilient navigation infrastructure for European commercial shipping.
What's your opinion on this?
Login or register to write comments and join the discussion!
Read more...

Video GIDAS - GNSS Interference Detection & Analysis System

published on 29 April 2021

OHB Digital Solutions GmbH develops systems for monitoring the GNSS frequency bands as well as detection, classification and localization of intentional or unintentional interference sources. Many stakeholders and applications as well as critical infrastructure providers are relying on GNSS to provide their services. Since Global Navigation Satellite Systems (GNSS) are widely used in safety and value critical applications, GIDAS detects, classifies and localizes any GNSS interference...

0

Article Operational notes & recommendations on Portable Pilot Units (PPU)

by United Kingdom Maritime Pilots Association - published on 2 December 2021

OPERATIONAL NOTES AND RECOMMENDATIONS by UKMPA, February 2017
The introduction of modern lightweight Portable Pilot Units (PPU) for use during pilotage has proved to be another major advance for pilotage operations worldwide.

1

Article New Study on GNSS Interference in the Baltic Sea

by GPSPATRON Sp. z o. o. - published on 12 March 2025

GNSS interference has become a growing challenge in the Baltic Sea, affecting maritime navigation, aviation, and critical infrastructure. While numerous datasets and services, such as gpsjam.org, spoofing.skai-data-services.com, and flightradar24, report high-altitude GNSS interference based on ADS-B data, there is a significant lack of studies focusing on ground-level interference.

3

Video Pilot Boat for sale: ProZero 12m DC lightpilot

published on 16 March 2020

The pilot vessel is located in Denmark. Please contact us by mail, we´ll forward your inquiry to the seller: info@marine-pilots.com Disclaimer: Marine-Pilots.com is only an intermediary for the sale and is not responsible for the completeness and accuracy of the information provided by the customer or for any errors in publication. BUILD YEAR 2015 DIMENSIONS: Length, Overall: 12.0 m Beam Overall (with fender): 3.0 m Draft (full load, hull): 0.95 m Displacement (full load): 6.400 kg...

0

Article Latest Edition of "The Pilot" by UKMPA released

published on 20 June 2022

Issue no. 332 of "The Pilot by United Kingdom Maritime Pilots´ Association is out now.

1

Article Unconfirmed reports say a pilot boat collided with the container ship GODSPEED in Taipei, Taiwan.

by Marine-Pilots.com - published on 9 March 2020

Apparently there were two crew members on board, but no pilot. One of crew was recovered and declared dead, another one, skipper of the boat, is missing.

0

Article Dardanelles: Turkish pilot falls from pilot ladder

by Frank Diegel - published on 8 March 2021

Eray Demirkol, one of the pilots of the Dardanelles Strait General Directorate of Coastal Safety, fell from the pilot ladder into the sea while he was boarding the 176-meter bulk carrier 28653 DWT named "Lord Nelson".

0

Video Kiel Pilots using VR for next-level shiphandling simulation

by Captain, MSc. Remko Fehr - published on 13 December 2023

Kiel Pilots introducing Morild Interaktiv AS Virtual Reality Simulator for next-level manoeuvring training

1

Video MAERSK: "We have made boarding safer for pilots on more than 100 ships"

published on 8 September 2022

Official Video by MAERSK:" In the past two years we have made boarding safer for maritime pilots on more than 100 ships."

1

Video Maritime Pilot - Mansoon in river Humber EP 10

by Dr. Captain Ahmed Sati - published on 18 December 2024

Episode 10 by Ahmed Sati

0