TABLE OF CONTENTS In 1899, a U.S. patent was issued for the use of the power network to control signal transmission. Information transmission over power network wires is called power line communication (PLC). Power networks of low ac voltage have a rated voltage of 230V and a frequency of 50 Hz (in Europe and a majority of countries worldwide), and a rated voltage of 110V and a frequency of 60 Hz (in the United States, Canada, and Japan). The greatest advantage of a data transmission channel formed by power network wires is the fact that the network is installed in almost every building.
Digital signal transmission over power network lines is used in many applications, especially in the following, as shown in Figure 6.46.
Equipment control in an apartment building (e.g., remote switching on, remote setting of a heater or an air conditioner, automatic switch-off of gas valves after detection of a fire or explosive conditions);
Internet connections. This application is rapidly developing; a maximum transmission rate of 45 Mbps was obtained in tests;
Data transmission from measurement devices, in particular from electricity meters or water and gas meters. Such measurement systems are briefly described below.
A number of factors, however, should be taken into consideration when designing a data transmission system over the power network.
Impedance mismatch of transmitters and receivers of signals with the network impedance. The impedance of a power line changes...
