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Twisted Pair English name is Twist-Pair. Integrated wiring project is the most commonly used as a transmission medium.
Twisted pair to each other using a pair of insulated metal wires twisted with each other as part of the way to resist the external electromagnetic interference. The two insulated copper wires twisted together with each other at a certain density, can reduce the degree of signal interference, each wire in the transmission of radio radiation would be yet another line the wave offset. "Twisted" the name is derived from this. Generally consists of two twisted-pair copper wire, 22-26 intertwined insulated from the actual use, multi-twisted pair twisted pair is wrapped in an insulated cables together inside the casing.The typical four twisted pairs, there are more on the twisted pair cable in a casing inside. These we call the twisted-pair cable. In the twisted-pair cable (also known as twisted pair cable), the different lines have different twist on the length, in general, twisted 38.1cm to 14cm in length, twist counterclockwise. Twisted pair of adjacent 12.7cm in length or more, usually more dense twisted line, the stronger the anti-interference ability, compared with other transmission media, twisted pair in the transmission distance, channel width and other aspects of data transmission speed subject to certain restrictions, but the price is relatively low.
Category 3 twisted-pair lines are common, both Category 5 and Category 5e cable, and the latest Category 6 cable, the former and the latter small diameter wire diameter, type the following:
1) a class of line: for the transmission of voice (a class of standard is mainly used for the early eighties before the telephone cables), different from the data transmission.
2) two types of lines: Transmission frequency 1MHZ, for voice transmission and high transmission rate of 4Mbps data transfer, common norms on the use of token-passing protocol 4MBPS old Token Ring.
3) three lines: means the standards currently specified in ANSI and EIA/TIA568 cable, the cable transmission frequency of 16MHz, for voice transmission and a maximum transfer rate of 10Mbps data transfer is mainly used for 10BASE - T.
4) four lines: the transmission frequency of such cables 20MHz, for voice transmission and high transmission rate of 16Mbps data transfer is mainly used for token-based LAN and 10BASE-T/100BASE-T.
5) The five lines: type of cable routing density increases, a high-quality insulation jacket, the transmission rate of 100MHz, for voice transmission and maximum transfer rate of 10Mbps data transmission, mainly for 100BASE-T and 10BASE-T network. This is the most commonly used Ethernet cable.
6) UTP cable: Category 5 with attenuation of ultra-small, low crosstalk, and has a higher attenuation and crosstalk ratio (ACR) and SNR (Structural Return Loss), a smaller delay error, performance is greatly increased. Super Category 5 cable is mainly used for Gigabit Ethernet (1000Mbps).
7) The six lines: the transmission frequency of such cables 1MHz ~ 250MHz, 200MHz when six cabling system in the integrated attenuation crosstalk ratio (PS-ACR) should have a larger margin, which provides 2 times the super-five of thebandwidth. Six cabling transmission performance over five standard is much higher than the optimum for the transmission of the application rate is higher than 1Gbps. Super six and five is an important difference is: an improvement in terms of crosstalk and return loss performance, full-duplex high-speed network for the new generation of applications, excellent return loss performance is very important. The elimination of the six standard basic link model, cabling standards with star topology, cabling distance requirements: a permanent link can not be longer than 90m, the channel length can not exceed 100m.
8) The seven types of lines: seven types of lines is the second line after the launch of six more parameters of products, currently no movement to the basic, the cable transmission frequency up to 600MHz, 500MHz and can provide at least the integrated attenuation crosstalk ratio , starting from the seven types of standards, the history of the emergence and wiring "RJ-type" and "non-RJ" type interface division. The "RJ-type" interface, currently amount to less than 600MHz of bandwidth, no final seven types of standard exposition of the international seminar on the seven categories are actively draft standard.But in July 1999, ISO / IEC received a non-RJ category Simon TERA interface standard, and in July 2002 to finalize the seven categories of Simon's non-RJ TERA interface.
Currently, non-shielded twisted-pair twisted pair can be divided into (UTP = UNSHILDED TWISTED PAIR) and shielded twisted pair (STP = SHIELDED TWISTED PAIR). Shielded twisted pair cables from the outer layer of aluminum foil package, to reduce the radiation, but it does not completely eliminate the radiation, the shielded twisted pair of relatively high prices, installation difficulties than unshielded twisted pair cables. Unshielded twisted-pair cable has the following advantages:
(1) No shield jacket, diameter is small, saves the space occupied;
(2), light weight, easy to bend, easy to install;
(3) to minimize crosstalk, or be eliminated;
(4) flame retardant;
(5) has the independence and flexibility for structured cabling.
Was divided in two categories in the 100-ohm cable, catamaran cable, large number of cables, 150 ohm shielded cable.
(PS: RJ is the acronym for Registered Jack. In the FCC (Federal Communications Commission standards and regulations) is to describe the public telecom network in the RJ interface, commonly used RJ-11 and RJ-45, the computer network is a standard RJ-45 commonly known as 8-bit modular interface. In the past four, five, super five, including the newly released six cabling, the RJ-type interfaces are used.