Patch cable

A patch cable ( engl. to patch - interconnect ), also patch cord is a cable type of network technology and telecommunications. Patch cables are mostly pre-assembled. The term originally refers patch cable cable lengths short (eg 50 cm or 1 m), but there is no particular cable standards, therefore any variable, not fixed cables connections are also commonly referred to as a patch cable. Patch cable or connecting cable is available in both fiber optic and copper design ( for example, twisted pair or twinax ( coaxial) patch cable for Ethernet or InfiniBand ).

When copper patch cables, the cores consist of flexible copper cable as opposed to static cables, which consist of solid wires. In fiber optic patch cables is no need for a complex cable structure and usually at duplex on flexible zipcord variants resorted (two easily separable separated fiber optic). The length of patch cables is usually about 0.3 to 25 m, for longer distances usually fixed connections are used.

Copper patch cables are either one to one wired (same positions of both plugs are connected to each other ), or certain pairs of wires are crossed ( cross cable ).

Use

The patch cable is used

• For connection of terminals ( ports ) of a patch panel (also called patch panel ) with ports of another patch panel; This connection is called a patch or ranking
• For connection of terminals ( ports ) of a patch panel to a network hub device (eg switch, hub or router)
• The connection of terminals ( eg PC with network card ) to a mains socket.

Types

Patch cables are used in various types of networks, for example in

• Ethernet networks, defined by the international standard TIA/EIA-568A/B
• Structured cabling
• Telephone distributions of telephone systems

Frequently encountered types of cables are especially twisted pair cables as well as coaxial cable and fiber optic cables.

Production of copper patch cable

In principle, patch cables for twisted - pair copper applications can be relatively easy to construct. However, it should be noted that the quality and goodness of a patch cable takes significant influence on the performance and quality of data transmission. Core diameter and quality of the meter plays a role, as the plug and the quality of the assembly. Factors such as "Power over Ethernet" and the related problems of the connector should this not be disregarded, and it is recommended to use consistently certified and tested ready-made patch cables.

Wiring

Regardless of the standard actually used the contacts of the RJ-45 plugs and jacks are numbered as follows:

According to the standard used contacts by TIA - 568A / B for 100BaseT be wired as follows:

The only difference between TIA - 568A and TIA -568B is the permutation of the colors of the wire pairs 2 and 3 (orange and green). Both standards wire the contacts one by one. As the wiring for both standards apart from the wire colors are the same, the cables are functionally identical. It is important that both ends of a cable is wired to the same standard ( one to one ).

TIA -568B is still quite prevalent in the United States for historical reasons. In Europe it is generally wired to TIA - 568A, as this assignment is consistent with the general color codes of the telephone installations.

Production

If one patch cable for Ethernet, 1000BASE -T or 100BASE- TX standard here, so in addition to the wrong cable quality (Cat 5 or better is required) the twist of a common source of error. Is the twist with ISDN or 10BASE-T due to the relatively low signal frequencies almost no effect, so it has an essential significance at 100 Mbps or Gigabit to.

Ethernet twisted pair cable uses symmetric differential signals to minimize electromagnetic radiation and irradiation. Therefore, it is important that the wire pairs are twisted together. This works ( idealized ) as follows: If on a wire of the pair of wires, a positive voltage, so is the same on the other wire an equally high negative voltage, therefore the resulting electromagnetic fields cancel each other. The same applies by analogy to the effects of external fields, the voltage is increased at one of the twisted wires, for example, 5 volts by the irradiation, thereby increasing this (due to twisting ), the voltage on the other wire also at 5 volts, whereby the differential signal is equal to is, so the light does not affect the signals. In any case, therefore, pin 1 and 2 form a twisted pair cable with 1000BASE -T and 100BASE- TX, the same is true for the pair on pins 3 and 6 (for 1000BASE -T and 100BASE- T4 cables also make pin 4-5 and 7-8 twisted pairs). Further, all wires of a pair should be as exactly the same length and the twisting may only on a short piece of cable ( max. 1.5 cm ) are missing or removed.

This type of error can only expensive high-frequency cable tester track (but also some Gigabit Ethernet NICs ). The simple LED tester, however, working with direct current and therefore do not know which wire pairs are twisted. All this of course also applies mutatis mutandis to 10BASE-T cabling, interfere with the wrong launched twisted wire pairs are by far less.

Production of fiber optic patch cable

In the manufacture of glass fiber and fiber optic patch cable, the fibers used are deducted ( for duplex a transmission [ TX transceiver ] and a receiving fiber [ RX- Receiver ] ) with special tool and glued into the ferrule (plug sleeve ) of a fiber optic connector. The fiber supernatant is broken then scribed and defined. The next step after the end face of the plug is ground flat with a polishing kit. The strain relief of the patch cable by means of a crimp on the connector body under the charge of the relief Kevlar yarn is clamped realized. Additional mechanical protection offered by the cable sheath and applied on the plug / cable transition bend protection sleeve. The grade and quality of a patch cable is determined by factors such as accuracy of the core hole in the ferrule, Kernexentrizität and roundness of the glass fiber and quality of polishing used significantly. Smallest scratches and dirt on the fiber end can possibly lead to massive destruction of the riser system and other components depending on the power density of the laser transmission. Apart from lead contamination and poor quality clothing quickly to an increase in system damping and increase the bit error rate. Is more important that the faces are in the production assessed and controlled individually by an interferometer and the quality of the materials used is continuously high. There are efforts to reduce by new techniques and advancements the sensitivity of such fiber optic patch cable to make it as user-friendly.