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Each pair is twisted to decrease interference.
Each pair is twisted to decrease interference.

Twisted pair cabling is a form of wiring in which two conductors (two halves of a single circuit) are wound together for the purposes of canceling out electromagnetic interference (EMI) from external sources; for instance, electromagnetic radiation from unshielded twisted pair (UTP) cables, and crosstalk between neighboring pairs. A cable is one or more Wires or Optical fibers bound together typically in a common protective jacket or sheath Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. In Electronics, the term crosstalk ( XT) refers to any phenomenon by which a signal transmitted on one circuit or channel of a Transmission system

Twisting wires decreases interference because the loop area between the wires (which determines the magnetic coupling into the signal) is reduced. In balanced pair operation, the two wires typically carry equal and opposite signals (differential mode) which are combined by addition at the destination. Differential signaling is a method of transmitting Information electrically by means of two complementary Signals sent on two separate wires The common-mode noise from the two wires (mostly) cancel each other in this addition because the two wires have similar amounts of EMI that are 180 degrees out of phase. This results in the same effect as subtraction. Differential mode also reduces electromagnetic radiation from the cable, along with the attenuation that it causes. Differential signaling is a method of transmitting Information electrically by means of two complementary Signals sent on two separate wires Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. In Physics, attenuation (in some context also called extinction) is the gradual loss in intensity of any kind of Flux through a medium

The twist rate (also called pitch of the twist, usually defined in twists per meter) makes up part of the specification for a given type of cable. The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International Where pairs are not twisted, one member of the pair may be closer to the source than the other, and thus exposed to slightly different induced electromotive force (EMF). Electromotive force ( emf, \mathcal{E} is a term used to characterize electrical devices such as Voltaic cells thermoelectric devices electrical

Where twist rates are equal, the same conductors of different pairs may repeatedly lie next to each other, partially undoing the benefits of differential mode. For this reason it is commonly specified that, at least for cables containing small numbers of pairs, the twist rates must differ.

In contrast to FTP (foiled twisted pair) and STP (shielded twisted pair) cabling, UTP (unshielded twisted pair) cable is not surrounded by any shielding. It is the primary wire type for telephone usage and is very common for computer networking, especially as patch cables or temporary network connections due to the high flexibility of the cables. Basic principle A traditional landline telephone system also known as "plain old telephone service" (POTS, commonly handles both signaling and audio information Computer networking is the Engineering Discipline concerned with communication between Computer systems or devices Networking routers A patch cable or patch cord (sometimes patchcable or patchcord) is an Electrical or Optical cable used to connect ("patch-in"

Contents

Unshielded twisted pair (UTP)

Unshielded twisted pair cable with different twist rates
Unshielded twisted pair cable with different twist rates

Twisted pair cables were first used in telephone systems by Alexander Graham Bell in 1881. Basic principle A traditional landline telephone system also known as "plain old telephone service" (POTS, commonly handles both signaling and audio information WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout By 1900, the entire American telephone line network was either twisted pair or open wire with similar arrangements to guard against interference. A telephone line or telephone circuit (or just line or circuit within the Industry) is a single-user circuit on a Telephone Today, most of the millions of kilometres of twisted pairs in the world are outdoor landlines, owned by telephone companies, used for voice service, and only handled or even seen by telephone workers. A landline, main line or fixed-line is a Telephone line which travels through a solid medium either metal Wire or Optical fibre

UTP cables are found in many ethernet networks and telephone systems. Ethernet is a family of frame -based Computer networking technologies for Local area networks (LANs For indoor telephone applications, UTP is often grouped into sets of 25 pairs according to a standard 25-pair color code originally developed by AT&T. The 25-pair color code is a Color code used to identify individual conductors in a kind of electrical Telecommunication Wiring for indoor use known as Before proposing a merge request please see Talk and see if the merger you propose has recently been made and A typical subset of these colors (white/blue, blue/white, white/orange, orange/white) shows up in most UTP cables.

For urban outdoor telephone cables containing hundreds or thousands of pairs, the cable is divided into smaller but identical bundles. Each bundle consists of twisted pairs that have different twist rates. The bundles are in turn twisted together to make up the cable. Pairs having the same twist rate within the cable can still experience some degree of crosstalk. In Electronics, the term crosstalk ( XT) refers to any phenomenon by which a signal transmitted on one circuit or channel of a Transmission system Wire pairs are selected carefully to minimize crosstalk within a large cable.

UTP cable is also the most common cable used in computer networking. A cable is one or more Wires or Optical fibers bound together typically in a common protective jacket or sheath Computer networking is the Engineering Discipline concerned with communication between Computer systems or devices Networking routers UTP cables are often called ethernet cables after Ethernet, the most common data networking standard that utilizes UTP cables. Ethernet is a family of frame -based Computer networking technologies for Local area networks (LANs Twisted pair cabling is often used in data networks for short and medium length connections because of its relatively lower costs compared to optical fiber and coaxial cable. An optical fiber (or fibre) is a Glass or Plastic fiber that carries Light along its length Coaxial cable is a cable consisting of an inner conductor surrounded by a tubular insulating layer typically made from a flexible material with a high Dielectric constant, all

UTP is also finding increasing use in video applications, primarily in security cameras. Video is the technology of electronically capturing, Recording, processing storing transmitting and reconstructing a sequence of Still images Closed-circuit television ( CCTV) is the use of Video cameras to transmit a signal to a specific place limited set of monitors Many middle to high-end cameras include a UTP output with setscrew terminals. Prosumer is a Portmanteau formed by contracting either the word pro fessional or pro ducer with the word con' sumer'. A Set screw, is a type of Screw generally used to secure an object within another object A screw terminal is a type of Electrical connector where a Wire is clamped down to Metal by a Screw. This is made possible by the fact that UTP cable bandwidth has improved to match the baseband of television signals. In Signal processing, baseband is an adjective that describes signals and systems whose range of Frequencies is measured from zero to a maximum bandwidth Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic While the video recorder most likely still has unbalanced BNC connectors for standard coaxial cable, a balun is used to convert from 100-ohm balanced UTP to 75-ohm unbalanced. The BNC ( Bayonet Neill Concelman) connector is a very common type of RF connector used for terminating Coaxial cable. A balun, ("bal-un" is a passive electronic device that converts between '''bal'''anced and '''un'''balanced Electrical The ohm (symbol Ω) is the SI unit of Electrical impedance or in the Direct current case Electrical resistance, A balun can also be used at the camera end for ones without a UTP output. Only one pair is necessary for each video signal.

History

The earliest telephones used telegraph lines, or open-wire single-wire earth return circuits. Single wire earth return (SWER or single wire ground return is a Single-wire transmission line for supplying single-phase electrical power In the 1880s electric trams were installed in many cities, which induced noise into these circuits. A tram, tramcar, trolley, trolley car, or streetcar is a railborne vehicle, of lighter weight and construction than a Train Lawsuits being unavailing, the telephone companies converted to balanced circuits, which had the incidental benefit of decreasing attenuation, hence increasing range. In law a lawsuit is a civil action brought before a Court in which the party commencing the action the Plaintiff, seeks a legal or equitable remedy See also Balanced line A balanced circuit is a common method of transmitting many types of communication signals between two points on two wires In Physics, attenuation (in some context also called extinction) is the gradual loss in intensity of any kind of Flux through a medium

Wire transposition on top of pole
Wire transposition on top of pole

As electrical power distribution became more commonplace, this measure proved inadequate. Two wires, strung on either side of cross bars on utility poles, shared the route with electrical power lines. A utility pole, telegraph pole, telephone pole, power (electricity pole, or telegraph post is a Pole used to support overhead Electric power transmission, a process in the delivery of Electricity to consumers is the bulk transfer of electrical power Within a few years the growing use of electricity again brought an increase of interference, so engineers devised a method called wire transposition, to cancel out the interference. In wire transposition, the wires exchange position once every several poles. In this way, the two wires would receive similar EMI from power lines. Today, such open-wire lines with periodic transpositions can still be found in rural areas. This represented an early implementation of twisting, with a twist rate of about four twists per kilometre, or six per mile. The kilometre ( American spelling: kilometer) symbol km is a unit of Length in the Metric system, equal to one thousand A mile is a unit of Length, usually used to measure Distance, in a number of different systems including Imperial units United States

Cable shielding

Main article: Electromagnetic shielding
S/STP, also known as S/FTP.
S/STP, also known as S/FTP. Electromagnetic shielding is the process of limiting the flow of Electromagnetic fields between two locations by separating them with a barrier made of conductive material

Twisted pair cables are often shielded in attempt to prevent electromagnetic interference. Because the shielding is made of metal, it may also serve as a ground. However, usually a shielded or a screened twisted pair cable has a special grounding wire added called a drain wire. This shielding can be applied to individual pairs, or to the collection of pairs. When shielding is applied to the collection of pairs, this is referred to as screening. The shielding must be grounded for the shielding to work.

Foiled Twisted Pair cable.
Foiled Twisted Pair cable.

Shielded twisted pair (STP-A)

STP cabling includes metal shielding over each individual pair of copper wires. This type of shielding protects cable from external EMI (electromagnetic interferences). e. g. the 150 ohm shielded twisted pair cables defined by the IBM Cabling System specifications and used with token ring networks. Token ring Local area network (LAN technology is a local area network protocol which resides at the Data link layer

Screened shielded twisted pair (S/STP)

S/STP cabling, also known as Screened Fully shielded Twisted Pair (S/FTP), [1] is both individually shielded (like STP cabling) and also has an outer metal shielding covering the entire group of shielded copper pairs (like S/UTP). This type of cabling offers the best protection from interference from external sources, and also eliminates alien crosstalk[1]. In Electronics, the term crosstalk ( XT) refers to any phenomenon by which a signal transmitted on one circuit or channel of a Transmission system

Screened unshielded twisted pair (S/UTP)

S/UTP, also known as Fully shielded (or Foiled) Twisted Pair (FTP), is a screened UTP cable (ScTP).

Note that different vendors and authors use different terminology, i. e. STP has been used to denote both STP-A, S/STP and S/UTP[2].

Advantages

Disadvantages

Minor twisted pair variants

See also

References

  1. ^ a b Grounding for Screened and Shielded Network Cabling - Siemon
  2. ^ Anitech Systems MP 4000 Manual

External links

"Tip" and "Ring" are common terms in the telephone service industry referring to the two wires or sides of an ordinary Telephone line. There are a few standards for Ethernet over twisted pair or Copper -based computer networking physical connectivity methods A registered jack ( RJ) is a standardized physical interface — both jack construction and wiring pattern — for connecting telecommunications equipment (commonly a Telephone TIA/EIA-568-B is a set of three Telecommunications standards from the Telecommunications Industry Association, a 1988 Offshoot of the EIA. Category 5 cable, commonly known as Cat 5, is a Twisted pair cable type designed for high signal integrity
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