Citizens band radio was a method of short-distance communication used by private citizens. It operated on the citizens band (CB), a group of radio frequencies that many nations reserve for private use. CB radio was most often used for conversations between places that were not linked by telephone. CB radio reached its peak of popularity in the 1970’s. Motorists and truck drivers used it to talk with other highway travelers or people who were in an office or at home.
Most CB sets were devices called transceivers, which consisted of a transmitter and a receiver. Some CB devices received radio signals but did not transmit them.
Most CB transmitters broadcast for distances of fewer than 5 miles (8 kilometers) in cities and up to 20 miles (32 kilometers) in rural areas. The broadcast range varied with the atmospheric conditions, the terrain, the design and height of the set’s antenna, and the amount of power supplied to the transmitter.
In most countries, including the United States and Canada, government regulations limit the power of a CB transmitter to a maximum of 4 watts. In the majority of countries, CB radio has 40 channels, with frequencies in the range of 26.96 to 27.41 megahertz. The Canadian CB is called General Radio Service. In several countries, including Canada, the United Kingdom, and the United States, channel 9 is reserved for emergency calls.
Remote controls for such devices as model airplanes and automatic garage-door openers also operate on CB radio frequencies. For more information on remote control, see Remote control .
