Editing Repeater (section)

==Overview==
When an information-bearing signal passes through a [[communication channel]], it is progressively degraded due to loss of power.  For example, when a [[telephone call]] passes through a wire [[telephone line]], some of the power in the [[electric current]] which represents the [[audio signal]] is dissipated as heat in the [[electrical resistance|resistance]] of the copper wire. The longer the wire, the more power is lost, and the smaller the [[amplitude]] of the signal at the far end. So with a long enough wire the call will not be audible at the other end. Similarly, the greater the distance between a [[radio station]] and a [[radio receiver|receiver]], the weaker the [[radio signal]], and the poorer the reception. A repeater is an electronic device in a communication channel that increases the power of a signal and [[Transmitter|retransmits]] it, allowing it to travel further. Since it [[amplifier|amplifies]] the signal, it requires a source of [[electric power]].

The term "repeater" originated with [[telegraphy]] in the 19th century, and referred to an [[electromechanical]] device (a [[relay]]) used to regenerate telegraph signals.<ref>{{cite book| last = Loring| first = A. E.E| title = A Hand-book of the Electro-Magnetic Telegraph| publisher = D. Van Nostrand| year = 1878| location = New York| pages = 53–54| url = https://archive.org/details/ahandbookelectr00lorigoog/page/n57 }}</ref><ref name=slyusar_relay>{{cite web| last= Slyusar| first= Vadym| title= First Antennas for Relay Stations| work= International Conference on Antenna Theory and Techniques, 21–24 April 2015| location= Kharkiv, Ukraine| date= 2015| pages= 254–255| url= http://www.slyusar.kiev.ua/U_080_Slyusar_ICATT_2015.pdf| access-date= 10 August 2017| archive-date= 24 September 2015| archive-url= https://web.archive.org/web/20150924102905/http://www.slyusar.kiev.ua/U_080_Slyusar_ICATT_2015.pdf| url-status= live}}</ref> 

Use of the term has continued in [[telephony]] and [[data communication]]s.

In [[computer networking]], because repeaters work with the actual physical signal, and do not attempt to interpret the [[data]] being transmitted, they operate on the [[physical layer]], the first layer of the [[OSI model]]; a multiport [[Ethernet]] repeater is usually called a [[Ethernet hub|hub]].