Twisted Pair Cabling Overview

Nowadays, fiber optic cable becomes one of the most popular mediums for both new cabling installations and upgrades, including backbone, horizontal, and even desktop applications. Though fiber offers a number of advantages over copper, copper still has a space in telecommunication networks, for example, direct attach copper cables, like HP JG081C 10G SFP+ direct attach copper cable or Cisco QSFP+ breakout cable (Cisco QSFP-4SFP10G-CU5M). As one of the oldest types of cable ever invented, twisted pair cable was first developed in 1881. Since then, it has been widely deployed for telephone line networks. Nowadays, the application of twisted pair cables has been extended worldwide mainly for outdoor land lines offering telephone voice service.

Introduction

Twisted pair cable is a kind of copper wiring made by putting two separate insulated wires together in a twisted pattern and running them parallel to each other. It is widely used in different kinds of data and voice infrastructures. To reduce crosstalk or electromagnetic induction between pairs of wires, two insulated copper wires are twisted around each other. Each connection on twisted pair requires both wires. Twisted pair can offset electromagnetic interference (EMI) from external sources to stop degrading the performance of circuit.

There are two twisted pair types: shielded and unshielded. A shielded twisted pair (STP) has a fine wire mesh surrounding the wires to protect the transmission; an unshielded twisted pair (UTP) does not. Shielded cable is used in older telephone networks, as well as network and data communications to reduce outside interference.

Different Categories of Twisted Pair Cabling

Also, different standards of twisted pair cables are specified into various categories as Cat 1, Cat 2, Cat 3, Cat 4, Cat 5/5e, Cat 6/6a, Cat 7/7a, Cat 8/8.1/8.2. And the following text will briefly introduce several categories.

Cat 5/5e

Cat 5 twisted pair cable is often used for structured cabling of computer networks. It is available to 10/100 Mbps speeds at up to 100 MHz bandwidth. However, it is now considered to be obsolete and replaced by Cat 5e (enhanced). Cat 5e is one the most commonly used twisted pair cables now. The biggest distinction between Cat 5 and Cat 5e is that Cat 5e has a lower crosstalk and its transmitting speed can reach up to 1000 Mbps.

Cat 6/6a

As a substitute of Cat 5/5e, Cat 6 twisted pair cable is applied to Gigabit Ethernet and other network physical layers. Cat 6 supports up to 10 Gbps speed at 250 MHz. When used for 10GBASE-T applications, Cat 6 has a reduced maximum length from 37 to 55 meters. Cat 6a (augmented) twisted pair cable has been evolved to perform at up to 500 MHz, thus the maximum cable distance is longer than Cat 6 of up to 100 meters.

Cat 7/7a

Cat 7 is the standard for twisted pair cabling used for 1000BASE-T and 10GBASE-T networks. It provides performance of up to 600 MHz with a maximum length of 100 meters. Cat 7a (augmented) twisted pair cable has a higher frequency of 1000 MHz. Results show that Cat 7a may be possible to support 40 GbE or even 100 GbE at a very short length.

Cat 8/8.1/8.2

Cat 8 is the USA standard specified by ANSI/TIA while Cat 8.1 and Cat 8.2 are specified by ISO/IEC for global application. All these three kinds of Cat 8 twisted pair cables are used for 25GBASE-T and 40GBSE-T at the maximum frequency of up to 2 GHz. Except Cat 8 adopts Cat 8 links, Cat 8.1 uses class I links and Cat 8.2 uses class II links. The key difference between class I and class II is that class II allows three different styles of connectors that are not compatible with one another, or with the RJ45 connector.

Conclusion

Twisted pair cables have been classified into different grades called categories. Higher categories are more expensive than lower ones, but most of the cost is actually spent on labor force for installing the cables. And twisted pair cables under Cat 5 are not recommended now. Higher categories are the future trends for network cabling.

Comparison Between Twisted Pair Cable, Coaxial Cable and Fiber Optic Cable

A communication system usually uses a wire or cable to connect transmitting and receiving devices. Currently, there are mainly three cable types deployed in communication systems, which are twisted pair cables, coaxial cables and fiber optic cables. Each type has been widely utilized in communication networks. What’s the difference between these three kinds of cables? This article will make a comparison between them.

Twisted Pair Cables

Twisted pair cable consists of a pair of insulated wires twisted together, which has been adapted in the field of telecommunication for a long time. With the cable twisting together, it helps to reduce noise from outside sources and crosstalk on multi-pair cables. Basically, twisted pair cable can be divided into two types: unshielded twisted-pair (UTP) cable and shielded twisted-pair (STP) cable. UTP cable, such as data communication cables and normal telephone cables, serves as the most commonly used cable type with merely two insulated wires twisted together. STP cable distinguishes itself from UTP cable in that it includes a foil jacket which helps to prevent crosstalk and noise from outside source. STP cable is typically used to eliminate inductive and capacitive coupling, and it can be applied between equipment, racks and buildings. The table below shows several different types of twisted pair cables.

Coaxial Cables

Coaxial cable is a type of high-frequency transmission cable which contains a single solid-copper core. A coaxial cable has over 80 times the transmission capability of the twisted-pair cable. Coaxial cables are commonly used to deliver television signals and to connect computers in a network as well. There are mainly two kinds of coaxial cables: 75 Ohm coaxial cable and 50 Ohm coaxial cable.

75 Ohm coaxial cable

The primary use of 75 Ohm coaxial cables is to transmit video signals. One typical application of 75 Ohm coaxial cable is to transmit television signals over cable, which is why sometimes it is called signal feed cables. The most common connector type used in this application is a Type F. Another application is video signals between components, such as DVD players, VCRs or receivers commonly known as audio/video (A/V) cables. In this case, BNC and RCA connectors are often found. In both applications, RG59 with both solid center conductor (RG59B/U) and stranded center conductor (RG59A/U) as well as RG6 are common choices.

50 Ohm coaxial cable

The primary use of 50 Ohm coaxial cables is the transmission of data signals in a two-way communication system. Several common applications for 50 Ohm coaxial cables are computer ethernet backbones, wireless antenna feed cables, GPS (Global Positioning Satellite) antenna feed cables and cell phone systems.

Fiber Optic Cables

Computing and data communications are fast-developing technologies. To meet the transmission of ever-increasing data rates, there comes a new generation of transmission medium, which is fiber optic cable. Fiber optic cable transmits information using beams of light at light speed rather than pulses of electricity. It refers to the complete assembly of optical fiber. A fiber optic cable can contain one or more strands of optical fiber to transmit data. Each strand of optical fiber is individually coated by plastic layers and contained in a protective tube. Fiber optic cable transmits data as pulses of light go through tiny tubes of glass, the transmission capacity of which is 26,000 times higher than that of twisted-pair cable. When comparing with coaxial cables, fiber optic cables are lighter and more reliable for transmitting data.

Two widely used types of fiber optic cables are single-mode fiber optic cables and multimode fiber optic cables. A single-mode optical fiber has a small core, and only allows one mode of light to propagate at a time. It is generally adapted to high speed and long-distance applications. A multimode optical fiber has a larger core diameter than a single-mode optical fiber and it is designed to carry multiple light rays, or modes at the same time. It is mostly used for communication over short distances because of its high capacity and reliability, serving as a backbone applications in buildings. And there are many connector types for fiber optic cable, such as LC, SC, ST or FC connector. You can choose fiber optic cables terminated at both ends with the same or different connector types to connect different devices, like LC SC fiber patch cable, LC to LC fiber patch cable. There are both single-mode and multimode, and simplx and duplex fiber optic patch cables for your options, such as LC to LC multimode duplex fiber optic patch cable, LC to SC duplex single-mode fiber optic patch cable, or LC LC multimode fiber patch cord.

Conclusion

As the technology in the field of network is developing rapidly, fiber optic cables seem to become the trend to meet the increasing demand of data rates in the market. However, whether to choose twisted pair cables, coaxial cables or fiber optic cables still depends heavily on applications. And other factors, such as the cost, transmission distance and performance, also need to be taken into consideration when making a choice.