Tunnel radio systems – design, implementation, maintenance, measurements

The tunnel radio system is used to establish radio connections between radio stations inside the tunnel, as well as between tunnel radio stations and external radio stations and control centers.

The primary purpose of the system is to provide radio communications for safety services, but it also enables rebroadcasting of public radio programs and the provision of any necessary information to users listening to those programs while driving through the tunnel.

The tunnel radio system consists of a central radio frequency station in the tunnel control center, tunnel amplifier substations, and an antenna and cable system.

A radiating cable is used as a receiving and transmitting antenna in the tunnel. It is a special type of coaxial cable with openings of a specific shape and arrangement on its outer conductor, allowing for radial radiation.

To connect the tunnel amplifier substations with the central RF station, single-mode fiber optic cables are used.

GSM base stations – design

As part of the construction of the mobile GSM network in the Republic of Croatia, it is necessary to design the projects for the GSM base stations.
This includes designing the antenna tower of the required height, along with a standard equipment container that needs to be connected to the electrical grid.

The project also encompasses the location of the distribution cabinet, equipment power supply, general and emergency lighting of the facility, air conditioning power supply, and connections for portable devices.

In addition to the high-voltage installations, the project covers low-voltage installations, grounding of equipment, and installations for weak current.

GSM-R Systems – Design, Field Measurements

GSM-R is a standard for using mobile telephony in railway traffic. To ensure coverage of the railway track with GSM-R signal, it is necessary to build a series of base stations in a redundant mode that will provide seamless coverage of the track and facilities (stations, stops).

Electromagnetic coverage is ensured through what is called dual redundancy. This means that in case of a failure in one of the base stations or the power supply, a minimum level of coverage will be guaranteed. In the event of a failure in one base transceiver station (BTS), the neighboring two stations will take over the coverage.

During system dimensioning, the frequency usage plan from EIRENE.SRS Chapter 3.5 is followed, as well as the relevant EIRENE.SRS recommendations and the EIRENE Functional Specification (EIRENE.FRS) on the services that the GSM-R network can provide now and in the future.

For network planning, signal coverage is defined as the field strength at the antenna on the locomotive roof (at a height of 4 meters from the track). It is assumed that an isotropic antenna with a gain of 0 dBi is used. This criterion must be met with a certain probability of coverage in the area.