In telecommunications, repeaters are electronic devices which receives and retransmits the signal. They are used so that the transmitted signal can reach longer distances. It is used to regenerate or replicate the analog or digital signals distorted by transmission loss. Analog repeaters can only amplify the signal whereas the digital repeaters can reconstruct the signal nearly to it’s original quality.

There are several types of repeaters such as telephone repeater used as amplifier in telephone lines, radio repeaters that retransmits radio signal signals, broadcast rely station is the repeater used to broadcast television and radio.

Generally when a signal is transmitted it looses its power gradually while covering large distances. For example if we consider a telephone line, it is made up of copper wire and when the signal passes over it over long distance, there is dissipation of power in the form of heat. Considering another example of radio, when it travels long distance, the signal becomes weaker and poorer that the receiver cannot hear the signal completely.

The repeaters regenerate or retransmit or amplify the signal so that the receiver could hear the signal clearly. Several repeaters can be used to amplify or regenerate the signals. For long distances when more repeaters are used, the output signal quality will be good.

Generally the term repeaters originated from telegraphy in the 19th century, and referred to electromechanical devices that regenerated the telegraphy signals. In radio, repeaters are used to widen the range of coverage. The history of radio relay repeaters began in 1898.

The radio repeater usually consists of a radio receiver connected to a radio transmitter. The received signal is often amplified or retransmitted on another frequency to provide coverage beyond obstruction.

Radio repeaters improve the communication coverage in systems using frequencies that typically have line of sight propagation. Without a repeater, the systems are limited in range by the curvature of the Earth and the block effect of terrain or high buildings. A repeater on a hilltop or tall building can allow stations that are out of each other’s line-of-sight range to communicate easily.

Thus repeaters play an important role in telecommunication system and is very essential device without which there may have been many challenges.