Twisted pair

As twisted pair cables or cables with twisted pairs are referred to in the telecommunications, computer technology news transmission and cable types, where the wires are twisted together in pairs. Pairs can with varying degrees of twist ( lay length ) and different directions of rotation are stranded in a cable. Twisted pair cables offer better protection against external alternating magnetic fields and electrostatic influences as cores that are only performed in parallel. By twisting the wire pairs to raise influences by external fields mostly on each other. Different stroke lengths of wire pairs to reduce this crosstalk between adjacent pairs in the cable. An electrically conductive shield (often made ​​of aluminum foil and / or braided metal, usually copper ) offers additional protection against harmful external electromagnetic fields. Twisted-pair cable without screen are called Unshielded Twisted Pair ( UTP) respectively. TP cable with an aluminum foil as a shield, bearing the letters FTP ( Foiled Twisted Pair). TP cable with a copper braid shield bearing the letters STP ( Shielded Twisted Pair). There are cables, in which the pairs are shielded from one another once again; these are, for example, with S / STP (Shielded Twisted Pair) or S / FTP refers (see below).

Twisted pairs are subjected to balanced signals to the far- end of a (longer) cable path, the difference between the signals of the two wires - means transformer or differential amplifier - form can, and in order to be able to reconstruct the transmission-side signal as possible at the receiving location ( CMRR / CMR ).

Cable with twisted pairs are used for a long time for signal and data transmission in computer technology initially for the parallel port of the printer, called the Centronics interface. Today appropriate cable for all types of signal transmission are used, inter alia, in the network technology, for example as an Ethernet cable or for structured cabling or the fieldbus.

• 2.1 Category 1
• 2.2 Category 2
• 2.3 Category 3
• 2.4 Category 4
• 2.5 Category 5/5e
• 2.6 Category 6/6a/6e 2.6.1 Category 6A/6A

Line construction

Twisted -pair cable contain pairs of two twisted together (english twisted ) pairs (English pair) of individual wires.

Details:

• Core: is a plastic-insulated copper conductors in Installations-/Verlegekabeln as rigid wire ( wire ) with a standard diameter of 0.4 mm or 0.6 mm. The default designation of a typical twisted-pair cable is accordingly 4x2x0, 4x2x0 or 4, 6: 4 → number of pairs;
• 2 → veins form a pair;
• 0.6 → diameter of a wire in mm

• Couple: Two wires are twisted to a pair, stranded several pairs in the cable.
• Conductor bundles or soul called the stranded together in the cable (often four) pairs. If more than one pair of the impact of different lengths are selected in order to reduce a Neben-/Übersprechen.
• Cable sheath: surrounds the soul. Usually consists of plastic mesh and smooth shell over it. Material used is often PVC or halogen -free material such as PE or aramid.
• Screen: metallic enclosure of individual wire pairs and / or soul. The shade is made of metal foil, metallized plastic film, wire mesh, or combinations thereof.

In addition to the other elements in the wire pairs may be present, such as:

• Drain wire: as an electrical ground line.
• Fülladern: made ​​of plastic to fill spaces between the pairs.
• Separating elements: plastic, to distinguish between the pairs.
• Plastic thread: ( for example, nylon ) between overall shield and sheath can be removed with a simple way of the cable sheath. To this end the thread with a pair of pliers to hold and pull back at an acute angle. The line will cut it to the envelope, it can now be easily removed.

Shielding

When using unshielded cables or connectors, there is no ground connection because of the isolation transformers used in the signal path between the network devices. The shield favors the electromagnetic compatibility ( EMC) and privacy; Interactions with other devices can be reduced. In case of multiple ground connections between the so- connected devices, however, is just through the screen a disturbing, mutual influence, the so-called ground loop possible. It is caused by voltage differences between the individual devices and causes transient currents in the ground, shield or PE compounds which can cause malfunctions. On many devices, the device ground to chassis ground and provided a corresponding contact in the power supply plug ( ' power cord, safety plug ') is present, even with the house ground, the PE conductor of the house wiring connected. Here special attention is then necessary with respect to ground loops and an unshielded cable may, in spite of the stronger irradiation then the interference received, the transmission quality even significantly - improved.

For differential or balanced signal transmission, a ground connection through a screen is not required, unless the common mode interference must be suppressed. An additional screen does not interfere with the protection mechanism of the twisting, it provides additional protection against common-mode interference.

The shield is designed to improve the immunity and suppress interference emissions. For a permanent link to the shield is connected to the respective components on both sides. The resulting transient currents act on the principle of Lenz's law, contrary to the magnetic field component of an electromagnetic wave. Ideal 360 ° contacts. The shielding effect of a line is measured as the transfer impedance.

Twisted -pair cable, there are, among others, in two - and four-pair design. With current network installations preferably four-pair cables are used. For installations from Cat.6 four-pair cables are mandatory.

Nomenclature

As the old names not or even are uniform and thus often confusing contradictory, a new naming scheme of the form XX / YZZ was introduced with the standard ISO/IEC-11801 (2002) e.

Where:

• XX for the overall screening: U = unshielded
• F = foil shield
• S = braid shield
• SF = braid and foil shield

• U = unshielded
• F = foil shield
• S = braid shield

• TP = Twisted Pair
• QP = Quad Pair

UTP

New designation according to ISO / IEC 11801 (2002) E: U / UTP

Cable with unshielded pairs and without overall shield (Unshielded Twisted Pair). In German-speaking UTP cables are rarely used, but it is the most commonly used cable for Ethernet LANs (> 90 % ) worldwide. For transmission method to Gigabit Ethernet UTP cable category 5e enough. Only for future techniques shielded cables are required ( 10 Gigabit Ethernet), but again there will be a standard that works with UTP cables - but with the restriction that only lower ranges will be possible. Under discussion are up to 50 m on UTP cables over 90 meters on STP cables.

Up to Category 6 UTP cable is because of its small outer diameter and the lack of umbrellas easy to work with and usually cheaper than STP cable types. The contrary is, however, that compared with the current-carrying components and cables significantly higher distances must be adhered to, as that would be necessary for shielded cables.

From Category 6A ( 10 Gigabit Ethernet) are artificially constructed in UTP cables asymmetries to counter Alien Next- problems in parallel conductors disposed. Due to this circumstance, the outer diameter is increased and usually even greater than with SF / FTP cables of category 7 and above.

STP

Screened cable ( shielded twisted pair) in different versions:

S / STP = screened shielded twisted pair ( with overall shield and wire mesh as a pair of screen )

F / STP = foiled shielded twisted pair ( with wire mesh as a pair and shielding foil as an overall shield)

FTP

New name by ISO/IEC-11801 (2002 ) E: U / FTP

The wire pairs are connected to a metallic screen (usually an aluminum- laminated plastic film ) surrounded ( Foiled Twisted Pair). For shielding of each pair is also called PiMF (pair in metal foil ), the screen includes two pairs, so even as ViMF ( four in metal foil ) is called. The current version of EN50173 -1 refers to this cable with FTP. Up to Category 6 typically was that the FTP cable had by this additional shielding a slightly larger outer diameter than UTP cable and something had greater bending radii. ( See notes from Category 6A UTP cables). However, FTP cables are less sensitive and more efficiently than UTP cable with regard to Alien Crosstalk effects and to lateral pressure in the rule. The crosstalk between the individual wire pairs can also be reduced by the shielding ( see also Electromagnetic Compatibility).

S / FTP, F / FTP or SF / FTP

New name by ISO/IEC-11801 (2002 ) E: S / FTP ( braid), F / FTP ( foil), SF / FTP ( foil braid )

Structure as FTP, but with an additional overall screen to the metallic conductor bundle ( Screened Foiled Twisted Pair). The overall shield can be designed as a film or as wire mesh or of both together. According to current EN50173 these cables are designated with an F for a foil shield, a S is a copper braid shield, a SF stands for a total shield of foil and braid. The degree of coverage of the braid should be above 30 % in order to achieve a sufficient shielding against low-frequency fields.

S / UTP, F / UTP or SF / UTP

New name by ISO/IEC-11801 (2002 ) E: S / UTP ( braid), F / UTP ( foil), SF / UTP ( foil braid )

Structure as UTP, but with additional metallic shield around the conductor bundle ( Screened Unshielded Twisted Pair). The overall screen can be implemented together as a film or as a wire mesh or of both. According to current EN50173 these cables are designated with an F for a foil shield, a S is a copper braid shield, a SF stands for a total shield of foil and braid.

ITP

An industrial cable variant ( Industrial Twisted Pair ) with S / STP cable construction. While having typical network patch cable or four pairs, ITP limited to only two pairs of wires.

WARP technology

A new technology for 10 Gigabit Ethernet, the cable length of 100 m were also met, the Swiss company R & M ( Reichle & De- Massari ) has brought to the market. It combines the advantages of shielded and unshielded technology. In this so-called " WARP technology " - the acronym stands for " Wave Reduction Patterns " - are shielded cables and modules with about 1 to 2 cm long metal foil segments and metal plates. Unlike previous shielding the film segments are not contacted and are not at ground potential. They are separated by small gaps and hang electrically, so to speak " in the air". A characteristic of these "floating shield " is that it builds virtually no capacity to earth. Thus, it does not affect the bandwidth of the transmission, but still offers a significant protection against near-end crosstalk, etc.

The combination of such " broken " Shielding and symmetrical signal transmission leads to disturbances that affect common to both wires ( common mode noise ) are eliminated by the symmetry of the signals; it is evaluated, only the difference between the two wires of a " twisted pairs " (one twisted pair ). And all those disorders that might affect only one of the two wires are intercepted by the twisting of the wires in the cable and for the most part of this special shielding.

Categories

To describe the performance / assets of a single component, the individual components of links (channels ), which typically consists of connecting components, cables and patch cables, divided into categories. Add a link component determined with the least capacity (Category ) the transfer class ( link class ) of the entire system. Higher categories automatically cover the underlying categories starting with. The interconnection of, for example, a Cat-5 Cat-6 cable with connector components reduces the Link class of theoretical class E to class D.

For ease of classification categories of each cable have been defined, each corresponding to a specific requirements. The categories 1 and 2 are defined only informally; categories 3 and 4 are no longer commercially relevant ( but still to be found in Altinstallationen ). Below are the seven defined categories:

Category 1

Cat -1 cables are designed for maximum operating frequencies up to 100 kHz and thus unsuitable for the data transmission. They are for voice transmission, for example in telephone applications, are used. Only available as a UTP cable.

Category 2

Cat -2 cables are suitable for maximal frequencies up to 1 or 1.5 MHz; they are used for example for a house wiring in the ISDN primary rate access.

Category 3

Cat 3 cable is unshielded twisted pair cables which are designed for maximum operating frequency of 16 MHz. It is a commonly laid in the U.S. type. In America, Cat -3 was for a long time the standard cable type for all telephone cabling. Cat -3 cables have a stroke length of three revolutions per foot for each twisted pair of copper wires. Another feature is that the lines of plastic ( perfluoro FEP ) can be isolated, so that only a small dispersion occurs. This is also important in laying the cable, it should be no preference for telephone cord by Cat -3 over Cat-5.

The cables are ISDN -compatible. 10 -Mbps Ethernet ( 10BASE -T) and can be run on Cat -3 cables, in addition to the 100BASE -T4 standard was developed. It provides 100 MHz on existing category 3 installations, all four pairs of wires are used - 100BASE -T4 has virtually no distribution outside of North America.

Cat -3 cables are scarcely offered today on sale yet.

Category 4

About Cat 4 cable 20 MHz can be transferred. You are a frequently laid in the U.S. type. Compared with Cat -3, it offered only a small improvement in speed and was generally ignored in favor of Cat-5.

Category 5/5e

Cat 5 cables are today predominantly encountered installed base; they are used for signal transmission at high data rates. The specific standard designation is EIA/TIA-568. Cat 5 cables are designed for operating frequencies up to 100 MHz. Due to the high signal frequencies must be used very carefully in the laying and installation, especially at the connection points of the veins.

Cat 5 cables are often used for structured cabling of computer networks, such as Fast or Gigabit Ethernet. This has promoted the spread of 1000BASE -T ( Gigabit Ethernet), since only a Cat-5 cable is required.

The introduction of 1000BASE-T (Gigabit Ethernet), and the associated signaling over all eight wires, instead of the current in the 10BASE -T and 100BASE- T only four wires, it is made ​​necessary that additional values ​​as PowerSum NEXT etc. taken into account. Components that meet the new requirements and were Gigabit Ethernet -ready were marked pending revision of the standards ISO11801 and EN50173 as Cat - 5e. Cat - 5e cables are backward compatible with traditional Cat 5 cables. With the Revision of Standards 2002/2003 Cat-5e disappeared as a term and is since then only Cat-5 called. Installations that were conducted prior to 2002 and the former Cat-5 corresponded accordingly need not necessarily be Gigabit Ethernet ready and the cables should be checked to see with special instruments before use. The properties of labeled " Cat-5 " cables can not be determined if the date of manufacture is not known.

The names EIA/TIA-568A and EIA/TIA-568B are also used informally to refer to the two specified in this standard assignments of the pairs color-coded to the terminal contacts of the RJ- 45 connector; says in this case, however, nothing about the transmission quality.

The test values ​​for cord and plug Cat-5e EIA/TIA-568A-5 meet the newer values ​​according to Class D of ISO / IEC 11801:2002 or EN 50173-1:2002.

Category 6/6a/6e

The Cat-6 cable is defined by the EN50288. Cat-6 cables are designed for operating frequencies up to 250 MHz. For greater lengths, slowing each other, low excess lengths are harmless but depending on outside influences. Security is ultimately the review with a corresponding test device that verifies the compliance with the limits of the current EN50173 -1, IS 11801, or the EIA / TIA 568B2.1.

Application fields for Cat-6 are voice and data transmission, multimedia and ATM networks. Powerful are cable to Cat -6a (500 MHz) according to EIA / TIA 568B2.1 Annex 10d. In the normalization phase of 10GBASE- T is a new Cat 6 specification was planned with a bandwidth of 625 MHz, as it (adopted IEEE 802.3, 2006) a transmission mode of 10GBASE- T are, supports this. This is however currently not pursued because it would have required new types of plugs over Cat 6a. In some publications and sales catalogs there is a term Cat-6 or Cat- 6e enhanced, while it is not a norm. Often so be assured of at least 55 m one product a fitness for 10GBASE -T.

Category 6A/6A

Category 6 augmented ( Cat 6A and Cat -6A ) is a standard that results from the increased bandwidth requirements of 10 Gigabit Ethernet ( 10GBASE -T), designed for transmission frequencies up to 500 MHz and distances up to 100 m as well as backward compatible with existing network protocols. Cat - 6A was the international standardization committee ISO / IEC (International Organization for Standardization / International Electrotechnical Commission) and Cat -6A by the U.S. EIA / TIA ( Electronic Industries Alliance / Telecommunications Industry Association ) established. The Cat-6 augmented demands higher technical conditions for the prevention of crosstalk and noise. The Name Category 6A or Cat -6A according to the international standard ISO / IEC 11801 always referred to one component and not the whole transmission path (channel), while Cat -6A both component and channel can be described.

Regarding the requirements for the transmission path (channel) for 10 Gigabit Ethernet, in Europe there are two valid standards: on the one hand the standard IEEE 802.3 IEEE ( Institute of Electrical and Electronics Engineers ), on the other hand, the Class EA according to ISO / IEC. However, the standard of the IEEE is not sufficient to fully describe the necessary requirements for the cabling infrastructure, because it defines fewer criteria than the standard of ISO / IEC. Therefore, for a comparison between the two variants of Category 6 augmented only the standard of ISO / IEC be used as a counterpart to that of EIA / TIA.

In the American Standard EIA / TIA 568 standard for the component to Cat -6A, and the transmission path to Cat -6A has been adopted since early 2008, but has 11801 fewer demands on the performance compared to the global ISO / IEC on. If you want to ensure the highest performance reserve for Channel and components that ISO / IEC standards are to be applied (Class EA for Channel Cat 6A for components).

The requirements for the component in accordance with ISO / IEC 11801 Category 6A in Appendix 2 (Amendment 2) were published in 2010 within the working group of ISO / IEC. To differentiate from the less powerful EIA/TIA-568B-Standard IEC is called the transmission path instead of Cat 6A and Class EA component characterized by a subscript A in the ISO / - ie the Category 6A component.

As the term Cat 6a is not protected, they can also be used within product names. The same was true even for Cat 6e or Cat- 7e. If the "a" is written in lower case, then there may be no official standard. The uppercase, gleichzeilige "A " refers to the American Standard with the lower requirements, the uppercase, subscript "A" stringent European standard. Whether it is in fact a component of the Category 6 is augmented, for example, an independent testing laboratory to the measurement method or direct probing re-embedded according to the limits of the standards, such as EIA / TIA or ISO11801 :2002- AMD2 (Draft as ). ensure A Certificate of Test gives users the assurance that he is actually a component of the Category 6 shall be augmented. Easily perceived the lower performance less at long distances, as they are often used in link - certificates, but rather for short distances < 15 m, since the compensating effect of the cable does not come really to bear here. For link lengths greater than 15 m can also be the case when using, for example, instead of a Category 7 cable only the cable is Category 6A.

With a transmission range of class EA, based on consistently tested in accordance with ISO / IEC Category 6A components to achieve a uniform, consistent performance of the entire cabling path and better protection for the signal transmission up to 500 MHz, used comes with 10 Gigabit Ethernet. The ISO / IEC standard ( components: Cat 6A channel: Class EA ) thus provides the user with more reserves and higher reliability.

Category 7/7A

Global Standard, except in the United States. Category 7 ( Class F ) enables operating frequencies up to 600 MHz, category 7A ( Class FA ) up to 1000 MHz.

Cat 7 cables have four individually shielded pairs (screened / shielded Foiled Twisted Pair S / FTP ) in a common screen. A Cat -7 cable meets the requirements of the standard IEEE 802.3 and is thus suitable for 10 Gigabit Ethernet.

The RJ -45 connector (see previous categories) can not meet these specifications because of the close contact arrangement; All RJ -45 CAT - 7 patch cables are a misnomer (as well as RJ -45 CAT-7 network outlets and panels). To establish network components according to CAT -7, new connections have been specially designed to substantially increase the distance between the wire pairs.

During the normalization phase to ISO/IEC11802: 2002 and EN50173 types of connectors were asked to vote. The decision was made on two different Stecker-/Buchsentypen, which are now defined as only approved Category 7/7A-Anschlusskomponenten.

• Nexans GG45 ( according to the standard because of its backward compatibility with RJ45 preferable in office cabling )
• Siemon TERA ( according to the standard for multimedia applications to be preferred )

Were not standardized components

• MMC 3000PRO

In the market, but all of these connections lead still a niche, since currently all common terminals are RJ -45 - based, so that such a transition at each terminal would require an appropriate adapter - except for GG -45, in addition to the GG -45 plug "normal" RJ -45 connectors and patch cables so accommodating. Today, often a CAT - 7 cable is used in conjunction with CAT-6-Netzwerkdosen/-Patchpanels for high-quality network cabling, which the entire network path, regardless of the "good" CAT 7 cable to Class E or EA level (CAT -6 ) degraded.

And 100 Gigabit Ethernet - IEEE standard 802.3ba with the next generation of Ethernet, 40 currently being evaluated. The success that these speeds can be achieved even with copper cabling to RJ45 base or Cat- 7- connection technology with ranges up to 100 m, is extremely low. A development in this direction is currently not well promoted.

Common twisted pair cable types (Overview)

Certification

Thus, a cable can be certified in accordance with any of the categories, it must meet certain requirements. For example, must be fully met for a Cat 6 certification the following points:

Measurement

To measure the transmission response is given to network analyzers from high-frequency technology a. A simple network analyzer with only two test ports only measures S- parameters. For the measurement of twisted- pair cables are particularly suitable Viertoranalysatoren, as they can directly measure the M parameter. By means of the M parameter allows the transfer function as well as the reflection behavior and the mode conversion of the common and differential mode waves directly represent. Also gives the group delay and the associated distortions from these measurements.