Twisted pair cable

Classification

Types of the twisted pair cable used at creation of wired networks exists a little:

• unshielded twisted pair (Unshielded twisted pair);
• shielded twisted pair (Shielded twisted pair);
• foil twisted pair (Foiled twisted pair);
• foil-and-braid twisted pair (Shielded Foiled twisted pair);
• the protected shielded twisted pair (Screened shielded twisted pair).

Categories

Shielding provides additional protection against electromagnetic interferences, both external, and internal. In addition to it in a cable multicore and solid wires can be applied. Today division of the twisted pair cable into 7 categories takes place. Two signs form the bases for similar division: frequency band and number of couples of conductors. Depending on a combination of quantitative values of these two signs it is possible to consider:

• CAT1 (frequency band 0.1 MHz)  — a telephone cable, only one pair (in Russia the cable was applied and in general without twists  — "noodles"  — at it are not worse than characteristic, but influence of noises is more). In the USA it was used earlier, only in the "twisted" type. It is used only for voice transmission or data by means of the modem;

• CAT2 (frequency band of 1 MHz)  — old cable type, 2 couples of conductors, supported data transmission at speeds up to 4 Mbps, was used in networks token ring and ARCNet. Now sometimes meets in telephone networks;

• CAT3 (frequency band 16 MHz)  — the 4-paired cable, was used at creation of local area networks 10BASE-T and token ring, maintains data transfer rate to 10 Mbps or 100 Mbps on technology 100BASE-T4. Unlike previous two, meets the requirements of the IEEE 802.3 standard. Also still meets in telephone networks;

• CAT4 (frequency band 20 MHz)  — a cable consists of 4 twisted pairs, was used in token ring networks, 10BASE-T, 100BASE-T4, data transfer rate does not exceed 16 Mbps on one pair, now is not used;

• CAT5 (frequency band 100 MHz)  — the 4-paired cable, was used at creation of local area networks 100BASE-TX, maintains data transfer rate to 100 Mbps when using 2 pairs. When laying new networks use a little advanced CAT5e cable (frequency band 125 MHz)  is and there is what is usually called "twisted pair cable", thanks to high transmission rate (up to 100 Mbps when using 2 pairs and up to 1000 Mbps when using 4 pairs) is the most widespread network media which are used in the computer networks still. Restriction for cable length between devices (the computer switch, a switch computer, a switch switch)  — 100 meters. Restriction a hub hub  — 5 meters;

• CAT6 (frequency band 250 MHz)  — is applied in networks Fast Ethernet and Gigabit Ethernet, consists of 4 couples of conductors and is capable to transfer data at a speed up to 1000 Mbps. It is added to the standard in June, 2002. There is a category CAT6a in which the frequency of the passed signal up to 500 MHz is increased. By data IEEE, 70 % of the networks set in 2004 used a category CAT6 cable;

• CAT7  — the specification on this cable type is not approved yet, data transfer rate up to 100 Gbps, the frequency of the passed signal up to 600 — 700 MHz. The cable of this category is screened. The seventh category, strictly speaking, not UTP, but S/FTP (Screened Fully shielded Twisted Pair).

See Also

SCS

Coaxial communication

Fiber optic communication