As we know there is a limit for any communication system to transmit the information. The coverage distance depends on modules used at the transmitter side viz. modulation scheme, amplifier, data format of the signal etc. In order to increase the communication distance of the system repeaters are used.

Repeater is a device which receives the signal and retransmits the signal after amplification. It may or may not does frequency conversion before retransmission depending upon applications of use. It usually consists of receiver, amplifier, frequency converter and transmitter. In some systems, repeater also does baud rate conversion before retransmission.

Repeater is used for wired medium (e.g. telephone line repeater, fiber optical cable repeater etc.) as well as wireless medium (e.g. satellite repeater, microwave repeater, wifi repeater, LTE repeater etc.).

Following are the two main repeater types based on data type it can handle.

Analog Repeater: It can amplify the analog signal in order to boost its amplitude. Usually trunking system employs FDM type of multiplexer which uses multiple analog signals in the form of current or voltage whose amplitude gets attenuated over transmission medium. The analog repeater is used here. It consists of linear amplifier and filters.

Digital Repeater: It can amplify the digital signal to compensate for losses over medium. Digital signal can be in any binary formats such as NRZ, RZ etc. It is also known by name “Digipeater”. This digipeater helps in pulse re-shaping, demodulation, decoding and re-synchronization at the receiver end.