PLC communication, power line communication

Power line communication (PLC) is the latest technique transmitting voice or data at a rapid speed through a power line. The power line communication technology utilizes a power line as a signal transmission channel. This technology makes it possible to perform communication between a plurality of communication devices by connecting each of those devices to a receptacle installed in each room in a house. In the power line communication (PLC), a radio frequency communication signal of a few hundreds Hz to a few tens MHz is transmitted together with an alternating power to a power line supplying the alternating power having frequencies of 50 to 60 Hz to houses, and a private access device receives only the communication signal for communicating. Generally, a PLC communication system comprises a plurality of communication stations connected to a single communication network. Each of the communication stations comprises a PLC for exchanging rapid data through the single communication network. A power line communication modem is a device that makes it possible to use these power lines as a communication line. The PLC modem converts digital data from an information processing unit such as a personal computer to analog signals, overlaps the signals with the power line of a commercial power source, converts the analog signals inputted through the power line to the digital signals and sends them to the information processing unit. The use of a power line as a communication channel provides a remarkable advantage in that additional expenses are not required for the construction of a new communication channel. The PLC may be applied to various fields such as superhigh-speed Internet communication, Internet phone, home networking system, home automation and remote metering system just by connecting a plug of a computer to a power source without using LAN or a telephone. Since no new wires are required to implement the function of communication, power-line communication systems greatly reduce the complexity and effort of installation, particularly in building retrofit applications in which it is highly desirable to be able to install an energy control system with little or no alteration of the existing electrical wiring.