Tunnels are critical components of transport infrastructure and highly reliable and available radio coverage in tunnels is essential for tunnel management, mission critical (Tetra / GSM-Rail / signaling / track- to-train radio / PMR / DMR / AM / FM) and commercial (2G, 3G, 4G and future 5G) wireless services in various frequency bands. Especially in train and metro tunnels, leaky cables seem to be the only solution because of the masking effects of the trains.

So, leaky cable, which is the key factor to radio communication system in tunnel, how to monitoring and fast & accurate fault locating are critical issues to tunnel management, telecom operator, system owner or maintenance team, due to the difficulty in making repair works in the tunnel while the train is in operation.

Based on Software Define Radio (SDR) technique, HELIOS® DTFMS™ Radiating Cable Distance-to-Fault Measure System is a powerful leaky cable performance monitoring platform, it is designed to be easily integrated into existing or new radiating cable system in tunnel by compact size and low power consumption, and enable keeping precisely measures parameters of the leaky feeder such as VSWR, Return-Loss etc., and conduct real-time verification, monitoring and fault locating for the radiating cable system.HELIOS® DTFMS™ Radiating Cable Distance-to-Fault Measure System mainly consists of four parts as below:

  • DTFMS™ Console Unit (CU): Generally will be deployed on radio BTS room or closed to HELIOS® M-DOTS™ OMU, and be in charge to centrally monitor and manage all DTFMS™ Measure Node (MN) in network through fiber link, it will receive data (such as operation status of device, alarm message, operation performance of leaky cable, distance to fault, timestamp etc.) from MNs.
  • DTFMS™ Measure Node (MN): it will be connected to the leaky cable by a directional coupler and it will keep monitoring and measuring the performance of leaky cable and regularly send measurement result and alarm message to CU via fiber link.
  • Bandpass Filter (Customization): Due to tiny low Tx power with customized frequency design without interfere with current radio communication systems, so generally we have to add a bandpass filter between DTFMS™ Measure Node (MN) and leaky cable in order to filter out the main signals in leaky cable to avoid so high RF power to overdrive the RF front-end of DTFMS™ Measure Node (MN).
  • Directional Coupler: Generally, we will recommend customer to choose to add -20dB Directional Coupler to connect DTFMS™ Measure Node (MN) to leaky cable as the insert loss should be only 0.3dB and very few influences existing radio coverage by leaky cable.

The DTFMS™ utilizes an embedded WEB management system for system configuration and network monitoring. The embedded WEB management system collects key performance and alarm information from leaky cable and send back alarm information to Helios® M-DOTS™ OMU through fiber link or directly integrated into customer’s existing NMS through SNMP V2&V3 trap with a MIB file.

Typical mounting options for the DTFMS™ include pole-mount and wall-mount. And the enclosure of the DTFMS™ is fully sealed IP-67 rated with compact design, which minimizes maintenance and is ideal for harsh environments.

Features & Benefits

  • Real-time monitoring operation performance of leaky cable system in tunnels and accurate fault locating function.
  • Low power consumption and compact design.
  • Easily integrated into existing radiating cable system.
  • Up to 2KM maximum measurement distance.
  • Accurate fault locating performance as +/-1meters error range.
  • Tiny low Tx power with customized frequency covering from 85-4000MHz without interfere with current radio communication systems.
  • Supports up to 4 RF ports for dual bore tunnels.
  • RJ-45 Port for Local Control and Alarming on an IP Web Browser GUI.
  • SNMP V2 & V3 support with a MIB File.
  • IP-67 rated aluminum enclosure for harsh environments and both support pole and wall mounted.
  • Efficiently minimize total cost of leaky cable maintenance for tunnel management, telecom operator, system owner and maintenance team

For more details please visit https://www.heliostelecom.com/product/dtfms-radiating-cable-distance-to-fault-measure-system/