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Power-line communication
Power-line communication (PLC) is the carrying of data on a conductor (the power-line carrier) that is also used simultaneously for AC electric power transmission or electric power distribution to consumers.
A wide range of power-line communication technologies are needed for different applications, ranging from home automation to Internet access, which is often called broadband over power lines (BPL). Most PLC technologies limit themselves to one type of wires (such as premises wiring within a single building), but some can cross between two levels (for example, both the distribution network and premises wiring). Typically transformers prevent propagating the signal, which requires multiple technologies to form very large networks. Various data rates and frequencies are used in different situations.
A number of difficult technical problems are common between wireless and power-line communication, notably those of spread spectrum radio signals operating in a crowded environment. Radio interference, for example, has long been a concern of amateur radio groups.
Appearing as early as 1925, carrier equipment for power lines was designed for use by electric utility companies to facilitate communication with technicians operating high voltage electrical equipment, which was often located hundreds of miles away from existing telephone infrastructure. Instead of running new dedicated telephone wires to remote locations, carrier equipment could be used to transmit telephone signals over high voltage power lines rated up to 220,000 volts. High voltage carrier equipment was installed by electricians and low voltage carrier equipment was installed by phone technicians.
The M carrier system was one of a series of early carrier systems developed by AT&T for long-distance communications. M1 carrier equipment was designed for use with rural 7,200 volt power lines and could be installed without disrupting power to the grid. By 1953 the Bell System had almost 10,000 M1 carrier stations in service.
Power-line communications systems operate by adding a modulated carrier signal to the wiring system. Different types of power-line communications use different frequency bands. Since the power distribution system was originally intended for transmission of AC power at typical frequencies of 50 or 60 Hz, power wire circuits have only a limited ability to carry higher frequencies. The propagation problem is a limiting factor for each type of power-line communications.
The main issue determining the frequencies of power-line communication is laws to limit interference with radio services. Wiring for power transmission typically uses unshielded cable. The unshielded cable may cause radio interference when the cable is used for high-frequency data signals; see Electromagnetic shielding for details.
Many nations regulate unshielded wired emissions as if they were radio transmitters. These jurisdictions usually require unlicensed uses to be below 500 kHz or in unlicensed radio bands. Some jurisdictions (such as the EU), regulate wire-line transmissions further. The U.S. is a notable exception, permitting limited-power wide-band signals to be injected into unshielded wiring, as long as the wiring is not designed to propagate radio waves in free space.
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Power-line communication AI simulator
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Power-line communication
Power-line communication (PLC) is the carrying of data on a conductor (the power-line carrier) that is also used simultaneously for AC electric power transmission or electric power distribution to consumers.
A wide range of power-line communication technologies are needed for different applications, ranging from home automation to Internet access, which is often called broadband over power lines (BPL). Most PLC technologies limit themselves to one type of wires (such as premises wiring within a single building), but some can cross between two levels (for example, both the distribution network and premises wiring). Typically transformers prevent propagating the signal, which requires multiple technologies to form very large networks. Various data rates and frequencies are used in different situations.
A number of difficult technical problems are common between wireless and power-line communication, notably those of spread spectrum radio signals operating in a crowded environment. Radio interference, for example, has long been a concern of amateur radio groups.
Appearing as early as 1925, carrier equipment for power lines was designed for use by electric utility companies to facilitate communication with technicians operating high voltage electrical equipment, which was often located hundreds of miles away from existing telephone infrastructure. Instead of running new dedicated telephone wires to remote locations, carrier equipment could be used to transmit telephone signals over high voltage power lines rated up to 220,000 volts. High voltage carrier equipment was installed by electricians and low voltage carrier equipment was installed by phone technicians.
The M carrier system was one of a series of early carrier systems developed by AT&T for long-distance communications. M1 carrier equipment was designed for use with rural 7,200 volt power lines and could be installed without disrupting power to the grid. By 1953 the Bell System had almost 10,000 M1 carrier stations in service.
Power-line communications systems operate by adding a modulated carrier signal to the wiring system. Different types of power-line communications use different frequency bands. Since the power distribution system was originally intended for transmission of AC power at typical frequencies of 50 or 60 Hz, power wire circuits have only a limited ability to carry higher frequencies. The propagation problem is a limiting factor for each type of power-line communications.
The main issue determining the frequencies of power-line communication is laws to limit interference with radio services. Wiring for power transmission typically uses unshielded cable. The unshielded cable may cause radio interference when the cable is used for high-frequency data signals; see Electromagnetic shielding for details.
Many nations regulate unshielded wired emissions as if they were radio transmitters. These jurisdictions usually require unlicensed uses to be below 500 kHz or in unlicensed radio bands. Some jurisdictions (such as the EU), regulate wire-line transmissions further. The U.S. is a notable exception, permitting limited-power wide-band signals to be injected into unshielded wiring, as long as the wiring is not designed to propagate radio waves in free space.