Repeater

A repeater (English literally for " repeater " ), also known as the regenerator, is in communication technology, an electrical or optical signal amplifier or dresser to increase the range of the signal. The repeater is located some distance from the transmitter, receives the signals and sends them into newly edited form further, resulting in a larger distance can be bridged.

In digital signal technology, the physical signal is sent on additional interpreted by the repeater and freshly coded and re-synchronized. Noise and distortion of the term ( jitter ), and the pulse shape to be removed by this processing from the received signal.

Simple repeaters, the transmitted information is not affected, only the processed electrical or optical signal. Contrast can add to the signal, eg an identifier that the traceability of the signal path allows for several possible paths more sophisticated digital repeaters.

Repeater in computer technology

In computer networks are repeaters components of the physical layer (layer 1 of the OSI model ), the extension of network segments.

Special variants of repeaters, transceivers and star coupler. A repeater with more than two terminals is also referred to as stroke, or multi- port repeaters. A media converter can be considered as a repeater so long as it does not bridge function.

Repeaters in the network technology

The use of repeaters is useful, for example, in LANs in bus topology to extend the maximum cable length of 185 m, for example, in 10BASE2. The repeater divides the network in two physical segments, but the logical bus topology is maintained. By this effect, the repeater increases the resilience of the network, since in case of failure of a subnetwork the respective other can continue to operate independently. In a "normal" bus topology would result in failure of the entire network. Repeaters do not increase the available bandwidth of a network.

A distinction is made in the LAN technology two types of repeaters:

• Local repeaters that connect two local network segments together, and
• Remote repeaters interconnecting two physically separate network segments via a so-called link segment. A link segment is composed of two repeaters linked to one another by fiber optic cables. This allows long distances to be bridged.

Repeater can not be cascaded in an Ethernet. Since associated with repeaters segments form a collision domain, two stations on the basis of maturities of the signal may only be so far apart that the collision detection is still working clearly. This is accomplished with the 5-4 -3- rule.

Repeaters in fiber-optic technology

In optical submarine cables, the light is every 50 to 80 kilometers into the cable incorporated optical amplifiers amplifies on the seabed. In addition, at longer intervals (approximately every 500 to 1000 miles) optical repeaters needed to regenerate the slope of the light pulses back and possibly compensate for offsets. The optical amplifier as well as the repeaters are supplied through the copper sheath of the cable with electrical power.

Wireless repeater

In information technology, known as a wireless repeater can be used to increase the range of a wireless radio network. In doing so, however, halved the data transmission rate of the radio network, since the repeater communicates with both the clients and the wireless access point.

Almost all modern, commercially available wireless access points offer a repeater mode to provide larger buildings, land and premises with a sufficient network coverage. With roaming clients can move freely within the coverage area of the network, without the traffic is affected by disconnections.

Repeaters in the telecommunications network

Repeater in telecommunication networks ( for example, SHDSL / G.SHDSL, HDSL and E1/Primärmultiplexanschluss ) are referred to primarily as repeaters ( ZWR). Areas of application, both the copper and the optical fiber transmission. The basic structure of the ZWR is identical for both applications:

There is usually a ZWR from an NT (Network Termination, Network Termination ) and LT ( Line Termination, line terminator ), which " back -to-back " (English: "Back - to-back" ) are connected together. The NT terminates the incoming transmission path ( eg SHDSL ) and decodes the digital values. By hard wiring the LT receives the digital values ​​, and encodes them in a new SHDSL signal. This, however this ZWR needs an additional power supply ( remote power supply ), which can be switched from the main distribution or (especially on routes with a second ZWR) on customer-side NT.

Repeater in ( mobile) radio networks

Also in mobile communications referred to as repeaters are used as relay stations for the " illumination" of shaded areas, such as buildings or subways.

Wireless network repeater for mobile networks (GSM, UMTS, Tetrapol ) are mainly used as two-way amplifier ( up and downlink) to zoom a cell site and to enable reception in buildings, garages, tunnels, ships, etc.. More intelligent repeaters can synchronize the electrical signal on the new regeneration of the signal quality addition, as for example in repeaters, which are used in Direktrufnetz of Deutsche Telekom.

Repeater amateur radio

Even in the amateur radio service Repeater play a role. In German-speaking countries they are called relay stations. Repeater for digital modes called this digipeater.