Raytrans Link Network Optical Terminal in Tunnel Construction Applications
During tunnel excavation, telephone, voice intercom, and voice broadcast stations need to be deployed along the route. At this time, the radio intercom distance is greatly limited, and more relay stations must be deployed along the route if it is to be used.
The industrial-grade optical-electrical integrated unit NTD421 with dual optical ports is used along the route. Each station can provide two telephone lines, and the central end needs to be connected to a telephone exchange. The application is shown in Figure 1.

Generally, video surveillance, stress detection, ventilation control, lighting control, etc. along the route can also be incorporated into the same communication system (however, in practical applications, these communication systems will separately use another set of communication equipment, generally using dual optical port media converters, plus serial port servers, plus POE power supply.
IDM POE-M08+=3 units of gigabit media converters+3 gigabit port and 8 fast Ethernet port Ethernet switches+4-port serial port server+150W 8-port POE power supply). As shown in Figure 2.

The following problems exist in these solutions:
When using an ordinary telephone exchange, if two users are on a call and other users have urgent business, priority calls such as forced release and barge-in cannot be implemented.
When using an independent telephone exchange, it cannot connect audio intercom terminals, broadcast terminals, wireless walkie-talkies, etc., which is not conducive to the converged communication of multiple communication methods.
When using a telephone exchange, functions such as conference calls and telephone broadcasting cannot be implemented.
It belongs to a different communication system from image communication, with many communication devices, many power interfaces, many optical fiber interfaces, messy installation, and complex maintenance.
Raytrans provides high-performance, integrated central-end and remote-end solutions. The central end provides an integrated audio/video dispatch switch IDM OMP2000-4E1-60 with dual gigabit optical ports. The remote end uses IDM GTD442, which can provide two physically isolated wire-speed gigabit Ethernet ports (usually one for video surveillance, the other for measurement data transmission, control data transmission, etc.). Four audio channels are used to provide telephone interfaces, intercom interfaces, public address broadcast interfaces, wireless walkie-talkie forwarding interfaces, etc. In addition, there are 2 RS485 interfaces, which can be aggregated to the central end's serial port server card and converted to Ethernet interfaces for connection to the data server.

