For relatively closed tunnels, due to the severe attenuation of longitudinal wave propagation and the tunnel conditions changing every day, the problem of wireless communication is difficult to handle. Due to the special environment of the tunnel itself, the shielding of all radio signals is very serious. Tunnel communication generally uses mobile communication equipment, so phones are not suitable for tunnel use.
Due to the special geographical environment of the tunnel, all radio signals are closely shielded. Therefore, the wireless communication system must cover many tunnels, and terminal radios can be used. Tunnel coverage is mainly divided into railway tunnels, highway tunnels and subway tunnels. Each tunnel has different characteristics, so different wireless intercom system coverage schemes should be customized for different projects.
Tunnel wireless intercom system project type
1.Coaxial cable passive distribution antenna system
The attenuation of the coaxial cable is small, and the choice of antenna gain depends mainly on the installation conditions. If conditions permit, you can use an antenna with relatively high gain to improve coverage. Suitable for short distance tunnels of 1000 meters.
2.Optical fiber coaxial cable active distributed antenna system
In tunnels, subways, coal mines, and caverns, fiber-optic coaxial active distributed antenna systems replaced coaxial cable passive distributed antenna systems. It is more suitable for covering underground tunnels (subway tunnels) and platforms. The main advantages of active distributed antenna systems with fiber optic coaxial cables include reducing the number of cables installed indoors. Can be applied to thinner cables. The use of fiber optic cables reduces electromagnetics.
At present, the rapid development of China's transportation industry is inseparable from expressway rail transportation. Therefore, professional wireless intercom system communication equipment has become the daily work of the tunnel. Emergency rescue and command and dispatch are essential equipment.