Radiating cables in critical infrastructure
A radiating cable is the RF backbone of every underground infrastructure: highway tunnels, railway galleries, subways, mining facilities. When it fails — through a short circuit, break, or progressive degradation — radio coverage disappears exactly where it is needed most. Monitoring continuity in real time is not optional: it is the difference between a system that works and one that does not know it has failed until the fault is already there.
What radiating cables are
Radiating cables (or leaky feeders) are coaxial cables with controlled openings in the outer shielding that radiate and receive radio signals along their entire length. Unlike conventional coaxial cables — which keep the signal confined — a radiating cable distributes uniform coverage in narrow, linear environments where point antennas cannot reach.
Where radiating cables are installed
| Environment | Typically supported services |
|---|---|
| Road and highway tunnels | Emergency services, traffic management, operational communications |
| Railway galleries | GSM-R, operations coordination, ETCS signaling |
| Subways | Operational communications, passenger information, cellular coverage |
| Mining and extraction facilities | PMR radio, safety communications, personnel tracking |
| Large industrial structures | PMR, emergency communications, ATEX systems |
| Ships and port facilities | Internal communications in shielded areas, maritime safety |
Supported radio services
Modern radiating cables carry multiple radio technologies simultaneously:
VHF / UHF (PMR)
- Bands 136–174 MHz (VHF) and 403–470 MHz (UHF)
- Professional digital DMR and analog communications
- High penetration in hostile environments
TETRA
- Bands 380–430 MHz
- European standard for public safety and law enforcement
GSM-R
- 876–880 MHz (uplink) / 921–925 MHz (downlink)
- European railway standard; EIRENE interoperability
Cellular networks (2G/3G/4G/LTE)
- Bands 800 / 900 / 1800 / 2100 / 2600 MHz
- Public coverage and onboard data services in tunnels or on trains
Why continuous monitoring matters
A radiating cable without monitoring is a system that only reports a fault when someone can no longer communicate. The main risks of an unmonitored network:
- Undetected short circuits — in a fire, the cable burns; without an immediate alarm, first responders enter a silent zone.
- Progressive breaks — a loosening connector degrades the signal over hundreds of meters before failing completely.
- Regulatory compliance — Italian regulations and EU tunnel directives require functioning radio systems; an undocumented fault is a compliance breach.
Continuous monitoring reverses the logic: degradation is caught before failure, maintenance becomes preventive, and every anomaly is logged with a timestamp for inspection audits.
TP-CCV2: radiating cable continuity monitoring
TP-CCV2 is the Teleproject system for real-time electrical continuity monitoring of radiating cables connected to base radio stations. Developed for the specific requirements of tunnels and large infrastructure, it is patented and installs directly in the BTS rack without interrupting the transmitted radio signal.
System components
| Component | Function | Notes |
|---|---|---|
| TP-CCV2 board | Main unit; monitors up to 4 radiating cables | 12 Vdc supply |
| ETPCV2 board | Expansion for additional branches from the same BTS | Powered via TP-CCV2 |
| TP-035 | Passive DC injector on the radiating cable | 50–500 MHz, max 200 W |
| TP-035A | DC injector for cable runs terminated with an antenna | 50–500 MHz, max 200 W |
The TP-035 and TP-035A are fully passive and require no maintenance.
How TP-CCV2 works
- DC injection — the TP-CCV2 board injects a low-level DC current into the radiating cable, invisible to radio signals.
- Continuous monitoring — the cable's electrical parameters are sampled 24/7; any anomalous variation is detected in real time.
- Instant alarms — short circuits (typical in fire events) and open circuits (breaks or defective connectors) generate immediate alarms via relay, SNMP, or web notification.
- NMS integration — data feeds into existing management systems for correlation with other infrastructure events and maintenance reporting.
Frequently asked questions
Does TP-CCV2 interfere with radio signals on the cable?
No. The system injects only a low-level DC current: it is physically separated from RF signals and does not interfere with DMR, TETRA, GSM-R, or LTE transmitted on the same cable.
How many radiating cables does a single TP-CCV2 monitor?
The main board monitors up to 4 radiating cables. Adding the ETPCV2 expansion board extends coverage to additional branches from the same base radio station.
What happens if the cable catches fire in a tunnel?
The combustion short circuit is detected within seconds and generates an immediate alarm. First responders and the control room are notified before radio service is completely interrupted.
Can it integrate with existing supervision systems?
Yes. TP-CCV2 exposes relay contacts and supports SNMP for integration with NMS platforms — such as Track-TP — already in use at the facility.