UIC Leaflet 751-2: Ground-to-Train Radio Systems – Technical Characteristics

What is UIC Leaflet 751-2?

UIC Leaflet 751-2 is a fundamental regulatory document titled “Railway radio equipment – Ground-to-train radio systems – Technical characteristics.” It serves as the bridge between the functional requirements defined in UIC 751-1 and the physical hardware implementation of Ground-to-Train Radio units.

The primary goal of this leaflet is to ensure Interoperability by standardizing the electromagnetic and interface parameters. This allows locomotives from different manufacturers to communicate effectively with the trackside infrastructure of various Infrastructure Managers (IMs), which is a critical requirement for Operational Safety in cross-border corridors.

Technical Parameters and Frequency Management

UIC 751-2 provides the precise technical data required for radio manufacturers and network planners. A major focus of the document is Frequency Management to prevent interference and ensure signal reliability.

• Frequency Bands: Standardization of the specific frequency ranges (historically the 450 MHz band for analog and 900 MHz for digital) allocated for railway use.
• Modulation and Channel Spacing: Defining how data is encoded and how much “space” is left between channels to prevent cross-talk.
• Mobile Station Power: Setting the transmission power limits for cab radios to ensure Radio Coverage without causing electromagnetic interference with other train systems.

Interface and Signaling Requirements

The leaflet also dictates how the radio unit interacts with the driver and the train’s internal systems:

• Call Signaling: Standardized tones and digital codes for different types of calls (e.g., individual, group, or emergency).
• Data Exchange: Protocols for transmitting short data messages, such as train position or status codes, between the train and the dispatcher.
• Human-Machine Interface (HMI): While the physical layout is often in UIC 617-5, this leaflet defines the logical responses of the radio (e.g., how the radio behaves when an emergency button is pressed).

Relationship with GSM-R and EIRENE

Historically, UIC 751-2 was the standard for analog “Type B” and “Type C” radio systems. However, with the advent of GSM-R, the technical specifications in this leaflet were used as the baseline for the EIRENE (European Integrated Railway Radio Enhanced Network) project.

Today, UIC 751-2 is often referenced alongside the System Requirements Specification (SRS) for GSM-R to ensure that digital transitions maintain the safety-critical features of legacy railway communication.

Comparison: Analog vs. Digital (GSM-R) Technical specs