Radio Laboratory at Fraunhofer CML: Understanding, Documenting, and Locating Radio Messages

In a nutshell: What does the radio lab do?

In addition to further developing AI-based applications such as the marFM^® maritime speech recognizer, the infrastructure provides opportunities for research and development projects focused on automated information gathering, maritime situational awareness, and digital assistance systems based on maritime radio communications. The infrastructure enables the reception of radio signals in the Port of Hamburg and beyond, the localization of transmitters, and the AI-based transcription of radio communications in various languages.

Infrastructure and Services

Certified Radio System

The certified radio system forms the technical foundation of maritime radio communication. It creates the conditions necessary to receive and analyze radio traffic under realistic conditions and to make it usable for research and development projects.

Antenna Platform for the Port of Hamburg and Beyond

The antenna platform enables radio reception in the Port of Hamburg and adjacent areas. It thus provides an important foundation for the analysis of maritime radio messages, the development of AI-supported applications, and the study of communication situations at sea.

Radio Direction Finder for Locating Transmitters

A radio direction finder helps locate transmitters. Combined with innovative localization algorithms, it is possible to calculate the most likely location from which a radio message was sent. This provides a better overview of communication situations and helps classify incoming messages.

Training AI-Based Transcription

The radio lab supports the training and further development of AI-based transcription for maritime radio messages in various languages. This takes into account typical challenges in shipping—such as poor audio quality, background noise, accents, dialects, Standard Marine Communication Phrases (SMCP), and ship names.

Classified Bridge Simulation

The classified bridge simulation complements the radio technology by incorporating the context of the ship’s bridge. This allows radio communication to be viewed not in isolation, but in conjunction with other bridge instruments as well as with procedures and decisions made on board a ship.

The “Stone Ship” in Harburg’s Inland Port

The radio and bridge laboratory combines two central elements: the antenna system and the classified bridge system. Together, they technically transform the research building into a real seagoing vessel—a “stone ship” in the heart of Harburg’s inland port. The combination of bridge and radio technology creates a unique research environment for maritime communication, navigation, and digital assistance systems.

marFM^®: AI-Based Speech Recognition for Maritime Radio Communications

marFM^® is a supplementary tool for conventional VHF radio developed at Fraunhofer CML. The solution automatically converts incoming maritime radio communications on board into text of the spoken language, documents radio traffic chronologically, and assists in locating transmitters. Most importantly: marFM^® is an offline application and requires no internet connection.

This provides responsible officers on board and staff in onshore coordination centers with a clearer overview of who transmitted what, when, and from where.

Why Maritime Radio Communication Is Challenging

VHF radio is critical to safety in shipping and is required equipment on board. At the same time, various factors can make it difficult to understand radio transmissions:

• Fluctuating transmission quality due to distance, antenna height, and weather conditions
• Engine noise and other background noise on board
• Multinational crews with different accents and dialects
• Standardized maritime call signs such as SMCP, as well as ship names

marFM^® was specifically developed and optimized for these acoustic and linguistic challenges.

Three components for a clearer overview

1. AI-based transcription and documentation

marFM^® automatically transcribes incoming radio messages. This allows misunderstandings to be identified more quickly and information to be understood more easily. Radio communications are documented chronologically so that the course of conversations can be reviewed later.

2. Analysis through Automated Identification

marFM^® also enables the automated analysis of transcribed radio messages through the targeted recognition and extraction of maritime entities (entity recognition). These include, for example, ship names, call signs, location data, etc., as well as other relevant information. Through the structured identification of this content, users can grasp relevant information more quickly, search specifically for certain ships, positions, or communication content, and establish connections between different messages.

3. Radio Direction Finding and Localization

Through radio direction finding and localization algorithms, the senders of radio messages can be located and identified. The combination of text, timestamps, and position information supports a rapid and well-founded situational assessment.

Benefits for Vessel Command and Coordination Centers

marFM^® and the Fraunhofer CML Radio Laboratory create added value for maritime communication:

• Capture radio messages faster: Spoken messages are made available as text.
• Detect misunderstandings earlier: Unclear or difficult-to-understand messages can be verified more easily.
• Tracking Communication: Chronological documentation makes it easier to review the course of conversations later on.
• Locating the Sender: Radio direction-finding shows where a message was sent from.
• Reducing Response Time: In critical situations, those in charge can act more quickly and proactively.

Whether it’s new communication systems, AI-powered applications, or innovative solutions for maritime safety, the radio laboratory offers a wide range of opportunities for companies, government agencies, and research institutions looking to develop or investigate new technologies for maritime applications. Get in touch with us!

Contact for collaboration inquiries: Dipl.-Ing. (FH) Jan Solle, jan.solle@cml.fraunhofer.de

FAQ

What is the Fraunhofer CML Radio Lab? The radio lab is a maritime research environment located in the Harburg inland port. It combines a certified radio system, an antenna platform, a radio direction finder, and a classified bridge system.

What is the range of the antenna platform? The antenna platform enables radio reception within the Port of Hamburg and beyond. It serves as the technical foundation for researching maritime radio communications.

What does marFM^® do? marFM^® automatically transcribes maritime VHF radio messages into text, documents radio traffic chronologically, and assists in locating transmitters.

Does marFM^® replace conventional VHF radio? No. marFM^® was developed as a supplementary tool to conventional VHF radio. The solution supports radio operators, particularly in situations where communication is difficult or critical.

What does “stone ship” mean? The Fraunhofer CML research building is referred to as a “stone ship” because its antenna system and classified bridge system technically make it a real seagoing vessel.

 

Last updated: October 2026