WordNet

(electronics) electronic device that amplifies a signal before transmitting it again; "repeaters can be used in computer networks to extend cabling distances"
a person who repeats; "the audience consisted largely of repeaters who had seen the movie many times"
do over; "They would like to take it over again" (同)take_over
an event that repeats; "the events today were a repeat of yesterdays" (同)repetition
to say again or imitate; "followers echoing the cries of their leaders" (同)echo
to say, state, or perform again; "She kept reiterating her request" (同)reiterate, ingeminate, iterate, restate, retell

PrepTutorEJDIC

繰り返す人(時) / 暗唱者 / 連発銃(repeating gun) / 2度打ち(壊中)時計 / 《米》(選挙の)二重投票者 / 《米》再履修学生
〈自分がすでに一度言ったこと)‘を'『繰り返して言う』 / 〈他人の言ったこと〉‘を'おうむ返しに言う;…‘を'他の人に繰り返して言う / …‘を'『暗記して言う』,暗唱する / …‘を'繰り返して行う(do again) / (食べたあとで)〈食物の〉味が残る / 〈小数が〉循環する / 繰り返すこと,反復すること / 繰り返されるもの,(公演の)再演;(番組の)再放送 / 反復楽節;反復記号(∥: :∥)

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/07/29 22:29:57」(JST)

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A radio repeater retransmits a radio signal.

In telecommunications, a repeater is an electronic device that receives a signal and retransmits it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances. It is a generic term that refers to several different types of devices; a telephone repeater is an amplifier in a telephone line, an optical repeater is an optoelectronic circuit that amplifies the light beam in a optical fiber cable; and a radio repeater is a radio receiver and transmitter that retransmits a radio signal. A broadcast relay station performs an analogous role in broadcast radio and television.

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 alternating electric current which represents the audio signal is dissipated as heat in the resistance of the copper wire. The longer the wire is, 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 farther from a radio station a receiver is, 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 retransmits it, allowing it to travel further. Since it 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.^[1] Use of the term has continued in telephony and data communications.

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.

Types

Telephone repeater: This is used to increase the range of telephone signals in a telephone line. They are most frequently used in trunklines that carry long distance calls. In an analog telephone line consisting of a pair of wires, it consists of an amplifier circuit made of transistors which use power from a DC current source to increase the power of the alternating current audio signal on the line. Since the telephone is a duplex (bidirectional) communication system, the wire pair carries two audio signals, one going in each direction. So telephone repeaters have to be bilateral, amplifying the signal in both directions without causing feedback, which complicates their design considerably. Telephone repeaters were the first type of repeater and were some of the first applications of amplification. The development of telephone repeaters between 1900 and 1915 made long distance phone service possible. However most telecommunications cables are now fiber optic cables which use optical repeaters (below).
- Submarine cable repeater: This is a type of telephone repeater used in underwater submarine telecommunications cables.
Optical communications repeater: This is used to increase the range of signals in a fiber optic cable. Digital information travels through a fiber optic cable in the form of short pulses of light. The light is made up of particles called photons, which can be absorbed or scattered in the fiber. An optical communications repeater usually consists of a phototransistor which converts the light pulses to an electrical signal, an amplifier to increase the power of the signal, an electronic filter which reshapes the pulses, and a laser which converts the electrical signal to light again and sends it out the other fiber. However, optical amplifiers are being developed for repeaters to amplify the light itself without the need of converting it to an electric signal first. Some repeaters have been powered by light energy transmitted down the fiber with the signal.
Radio repeater: This is used to extend the range of coverage of a radio signal. A radio repeater usually consists of a radio receiver connected to a radio transmitter. The received signal is amplified and retransmitted, often on another frequency, to provide coverage beyond the obstruction. Usage of a duplexer can allow the repeater to use one antenna for both receive and transmit at the same time.
- Broadcast relay station, rebroadcastor or translator: This is a repeater used to extend the coverage of a radio or television broadcasting station. It consists of a secondary radio or television transmitter. The signal from the main transmitter often comes over leased telephone lines or by microwave relay.
- Microwave relay: This is a specialized point-to-point telecommunications link, consisting of a microwave receiver that receives information over a beam of microwaves from another relay station in line-of-sight distance, and a microwave transmitter which passes the information on to the next station over another beam of microwaves. Networks of microwave relay stations transmit telephone calls, television programs, and computer data from one city to another over continent-wide areas.
  - Passive repeater: This is a microwave relay that simply consists of a flat metal surface to reflect the microwave beam in another direction. It is used to get microwave relay signals over hills and mountains when it is not necessary to amplify the signal.
- Cellular repeater: This is a radio repeater for boosting cell phone reception in a limited area. The device functions like a small cellular base station, with a directional antenna to receive the signal from the nearest cell tower, an amplifier, and a local antenna to rebroadcast the signal to nearby cell phones. It is often used in downtown office buildings.
- Digipeater: This is a term used usually for a repeater node in a packet radio network. It performs a store and forward function, passing on packets of information from one node to another.

Repeaters can be divided into two types depending on the type of data they handle:

Analog repeater: This type is used in channels that transmit data in the form of an analog signal in which the voltage or current is proportional to the amplitude of the signal, as in an audio signal. They are also used in trunklines that transmit multiple signals using frequency division multiplexing (FDM). Analog repeaters are composed of a linear amplifier, and may include electronic filters to compensate for frequency and phase distortion in the line.
Digital repeater: or digipeater This is used in channels that transmit data by binary digital signals, in which the data is in the form of pulses with only two possible values, representing the binary digits 1 and 0. A digital repeater amplifies the signal, and it also may retime, resynchronize, and reshape the pulses. A repeater that performs the retiming or resynchronizing functions may be called a regenerator.

Talk around channel

In a system using radio repeaters, a designated channel may be provided that allows direct mobile-to-mobile communication. This "talk-around channel" can be used if the repeater is out of order, busy, or if the mobiles are operating out of the coverage area of the repeater.

Usage of Repeater Talk around channel frequency

Amateur radio repeater bands

Repeater Bands	Usages ^[2]
6 Metre Repeaters	On the 6 metre band, repeaters provide local coverage but interstate contacts also happen quite often during times of high solar activity. There are 18 repeater channels on this band, with output frequencies beginning at 53.550 MHz.
2 Metre Repeaters	2 metres is the main band for repeater activity. There are 16 channels between 146.625 and 147.000 MHz, and 15 channels above 147 MHz.
70 cm Repeaters	The 70 cm band is the other major band for repeater activity.It has a total of 58 repeater channels with their outputs between 438 - 440 MHz and inputs 5 MHz lower. Shorter than 70 cm band ( example 450–470 MHz:): This band repeater is commonly used for UHF State Emergency Service Analogue Radio Channels, UHF business band and Public Safety band

Telephone repeater

Before the invention of electronic amplifiers, mechanically coupled carbon microphones were used as amplifiers in telephone repeaters. After the turn of the century it was found that negative resistance mercury lamps could amplify, and they were used.^[3] The invention of audion tube repeaters around 1916 made transcontinental telephony practical. In the 1930s vacuum tube repeaters using hybrid coils became commonplace, allowing the use of thinner wires. In the 1950s negative impedance gain devices were more popular, and a transistorized version called the E6 repeater was the final major type used in the Bell System before the low cost of digital transmission made all voiceband repeaters obsolete. Frequency frogging repeaters were commonplace in frequency-division multiplexing systems from the middle to late 20th century...

References

^ Loring, A. E. (1878). A Hand-book of the Electro-Magnetic Telegraph. New York: D. Van Nostrand. pp. 53–54.
^ http://www.wia.org.au/members/repeaters/about/. Missing or empty |title= (help)
^ Sungook, Hong (2001). Wireless: From Marconi's Black-Box to the Audion. MIT Press. p. 165. ISBN 0262082985.

External links

English Journal

Heralded high-efficiency quantum repeater with atomic ensembles assisted by faithful single-photon transmission.

Li T1, Deng FG1,2.
Scientific reports.Sci Rep.2015 Oct 27;5:15610. doi: 10.1038/srep15610.
Quantum repeater is one of the important building blocks for long distance quantum communication network. The previous quantum repeaters based on atomic ensembles and linear optical elements can only be performed with a maximal success probability of 1/2 during the entanglement creation and entangle
PMID 26502993

Controlled Rephasing of Single Collective Spin Excitations in a Cold Atomic Quantum Memory.

Albrecht B1, Farrera P1, Heinze G1, Cristiani M1, de Riedmatten H1,2.
Physical review letters.Phys Rev Lett.2015 Oct 16;115(16):160501. doi: 10.1103/PhysRevLett.115.160501. Epub 2015 Oct 12.
We demonstrate active control of inhomogeneous dephasing and rephasing for single collective atomic spin excitations (spin waves) created by spontaneous Raman scattering in a quantum memory based on cold ^{87}Rb atoms. The control is provided by a reversible external magnetic field gradient inducing
PMID 26550854

Storage of multiple single-photon pulses emitted from a quantum dot in a solid-state quantum memory.

Tang JS1,2, Zhou ZQ1,2, Wang YT1,2, Li YL1,2, Liu X1,2, Hua YL1,2, Zou Y1,2, Wang S1,2, He DY1,2, Chen G1,2, Sun YN1,2, Yu Y2,3, Li MF2,3, Zha GW2,3, Ni HQ2,3, Niu ZC2,3, Li CF1,2, Guo GC1,2.
Nature communications.Nat Commun.2015 Oct 15;6:8652. doi: 10.1038/ncomms9652.
Quantum repeaters are critical components for distributing entanglement over long distances in presence of unavoidable optical losses during transmission. Stimulated by the Duan-Lukin-Cirac-Zoller protocol, many improved quantum repeater protocols based on quantum memories have been proposed, which
PMID 26468996

Towards quantum networks of single spins: analysis of a quantum memory with an optical interface in diamond.

Blok MS1, Kalb N, Reiserer A, Taminiau TH, Hanson R.
Faraday discussions.Faraday Discuss.2015 Sep 28. [Epub ahead of print]
Single defect centers in diamond have emerged as a powerful platform for quantum optics experiments and quantum information processing tasks. Connecting spatially separated nodes via optical photons into a quantum network will enable distributed quantum computing and long-range quantum communication
PMID 26411802

Japanese Journal

直接中継型リピータのアンテナ間アイソレーション評価 (アンテナ・伝播)

中野雅之
電子情報通信学会技術研究報告 : 信学技報 112(187), 69-74, 2012-08-27
NAID 40019409611

畜冷剤(保冷剤)を用いたミニサテ蓄電池の低温対策(送受信技術,放送現業技術および一般)

荒井華女,畑田勘治
映像情報メディア学会技術報告 36(30), 29-32, 2012-07-12
極微小電力テレビ中継放送所(以下ミニサテという)には、停電時の予備電源として蓄電池を設置している。北海道では、冬季の外気温が-30度以下まで低下するミニサテがあり、蓄電池の仕様上の温度範囲である-15〜+15度の下限を下回る。低温では放電可能時間が短くなり、極低温で電解液が凍結すると放電不能となる可能性がある。そこで、凝固点が氷点下にある蓄冷剤(保冷剤)を用い、蓄電池の温度低下を緩和する手法につい …
NAID 110009496524

イギリスでの研究生活 : 海外研究リピータになるまで

石井真史
表面科学 : hyomen kagaku = Journal of the Surface Science Society of Japan 33(6), 363-364, 2012-06-10
NAID 10030756549

無線秘密鍵共有システムに対する能動的盗聴法の提案と実証

藤木雄大,吉田斉史,斎藤隆史,坂井尚貴,上原秀幸,大平孝
電子情報通信学会技術研究報告. A・P, アンテナ・伝播 111(487), 43-48, 2012-03-08
… 本稿では,無線秘密鍵共有システムに対し支配的な素波を生成する双方向増幅中継装置BAR(Bidirectional Active Repeater)を用いた能動的盗聴法を提案する.シミュレーションを行った結果,BARを用いたとき正規局のRSSI(Received Signal Strength Indicator)履歴と盗聴局のRSSI履歴の相関が高められることを確認した.実証実験を行った結果,CDF=0.5となる盗聴情報量は提案盗聴法を実行したとき受動的盗聴法に比べ19ポイント向上することを確認し …
NAID 110009545720

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