• A repeater is a network device that retransmits a received signal with more power and to an extended geographical network boundary than what would be capable with the original signal.
  • It is implemented in computer networks to expand the coverage area of the network, repropagate a weak or broken signal.
  • Repeaters amplify the received/input signal to a higher frequency domain so that it is reusable, scalable and available.
  • Repeaters were introduced in wired data communication networks due to the limitation of a signal in propagating over a longer distance and now are a common installation in wireless networks for expanding cell size.
  • It supports both analog and digital signals and can repeat electrical and light-based signals.
     Types of repeaters:
     - Telephone repeaters:
  • Telephone repeaters were the first type of repeaters.
  • The development of telephone repeaters between 1900 and 1915 made long distance phone service possible. 
  • They are most frequently used in trunklines that carry long distance calls.  
  • Submarine cable repeater is a type of telephone repeater used in underwater submarine telecommunications cables.
     - Optical cable repeaters:
  • It is used to increase the range of fiber optic cables. Digital information travels through a fiber optic cable in the form of short pulses of light. 
  • An optical communications repeater usually consists of a photo transistor which converts the light pulses to an electrical signal, a laser again converts the electric signal into light pulses.    
     - Radio repeaters:
  • It is used to extend the range of coverage of radio signal. It contains radio transmitter and radio receiver and a duplexer to transfer the signal.   

  • Repeaters receive radio waves on one frequency, called the input frequency, and then re-transmit the information on its output frequency. Therefore if you use two way radios with a radio repeater service.
     Advantages:
  • Cost effective 
  • Simple to connect
  • Ability to strengthen signal
      Disadvantages:
  • Too many repeaters on a network create noise on the wire and increase the likelihood  of packet collision.
  • When repeater has been used between segment A and B, whether there is a station in segment B or not, this is the final destination.