Powerline Communications (PLC)

Powerline Communications (PLC), also called Power Line Telecommunications (PLT) is the use of the existing public and private mains power wiring for the transmission of telecommunication signals. There are four basic forms of powerline communications:

• In-house networking
  In-house mains power wiring can be used for high speed data transmission for home networking;
• Broadband over Power Line
  The outdoor mains power wiring can be used to offer broadband internet access;
• Narrowband in-house applications
  In-house mains power wiring can be used for low bit rate services like home automation and intercoms.
• Narrowband outdoor applications
  Narrowband outdoor applications are mainly used by the utility companies for automatic meter reading and remote surveillance and control.

How does PLC work?
The power line is transformed into a communication network through the superposition of a low energy information signal to the power wave. In order to ensure that the power wave does not interfere with the data signal, the frequency range used for communication is very far from the one used for the power wave (50 Hz in Europe and 60 Hz in the U.S.). The frequency range used for PLC narrowband applications is 3 kHz to 148,5 kHz and from 1 MHz to 30 MHz for PLC broadband applications.

Interference
The biggest problem for PLC is that the power wiring is unshielded and untwisted. The wiring acts as an antenna. This means that the wiring will emit large amounts of radio energy. This will cause interference to the existing users of the same frequency band (1 - 30 MHz for broadband outdoor power line communications). The BPL systems will also get interference from radio signals.