In every communication system, it is the communication channels that play an essential role during the process of data transfer. Basically, there are two categories of communication channels. One category is wireless connection that uses air to achieve the transmission. While the other category is physical connection, which adopts a solid substance such as a wire or cable to connect sending and receiving devices. These connections include fiber optic cable, twisted- pair and coaxial cable. Since each of them can be equally applied into network communication, how they distinct from each other in terms of features and specifications. This article aims to explain the differences among these three kinds of cables and meanwhile to offer some suggestions and tips as well.
Twisted pair cable consists of a pair of insulated wires twisted together, which is 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. Twisted pair cable works well on transferring balanced differential signals, the merits of which are extremely valuable in wide bandwidth and high fidelity system. Basically, twisted pair cable can be divided into two types: unshielded twisted-pair (UTP) and shielded twisted-pair (STP). The former serves as the most commonly used one with merely two insulated wires twisted together. Any data communication cables and normal telephone cables belong to this category. However, shielded twisted pair distinguishes itself from UTP in that it consists of a foil jacket which helps to prevent crosstalk and noise from outside source. It is typically used to eliminate inductive and capacitive coupling, so it can be applied between equipment, racks and buildings. With the advancement of technology, the twisted pair cables are now being phased out by more technically developed and reliable media.
|CAT1||Up to 1Mbps, Old Telephone Cable|
|CAT2||Up to 4Mbps, Token Ring Networks|
|CAT3||Up to 10Mbps, Token Ring & 10BASE-T Ethernet|
|CAT4||Up to 16Mbps, Token Ring Networks|
|CAT5||Up to 16Mbps, Token Ring Networks|
|CAT5e||Up to 1Gbps, Ethernet, Fast Ethernet, Gigabit Ethernet|
|CAT6||Up to 10Gbps, Gigabit Ethernet, 10G Ethernet(55 meters)|
|CAT6a||Up to 10Gbps, Gigabit Ethernet, 10G Ethernet(55 meters)|
|CAT7||Up to 10Gbps, Gigabit Ethernet, 10G Ethernet(100 meters)|
Coaxial cable acts as a 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. It is commonly used to deliver television signals and to connect computers in a network as well, so people may get more familiar with this kind of cable. Coaxial cable has always been the mainstay of high speed communication and has also been applied to network with 10 gigabit links data centers, because it is proved to be cost efficient for short links within 10 m and for residential network. Besides, it features anti-jamming capability, stable transmission of data and money saving. Coaxial cable is widely employed in feedlines connecting radio transmitters and receivers, computer network connection, digital audio and television signals distribution. Moreover, coaxial cable can effectively protect signals from being interfered by external electromagnetic influence.
Computing and data communications are fast-moving technologies. There comes a new generation of transmission media—fiber optic cable. It refers to the complete assembly of fibers, which contain one or more optical fibers that are used to transmit data. Each of the optical fiber elements 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 reliable for transmitting data. They transmit information using beams of light at light speed rather than pulses of electricity.
There exist various different types of fiber optic cables, which are determined by the number of fibers and where it will be installed. Besides, the bandwidth of optical fiber transmission is also developed and the maximum connection distance can reach up to over 2 km. Nowadays, two types of fiber optic cables are widely adopted in the field of data transfer—single-mode fiber optic cables and multimode fiber optic cables. A single-mode optical fiber is a fiber that has a small core, and only allows one mode of light to propagate at a time. So it is generally adapted to high speed, long-distance applications. While a multimode optical fiber is a type of optical fiber with a core diameter larger than the wavelength of light transmitted 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.
From what we have discussed above, you may have a better understanding of single-mode fiber and multimode fiber. It’s time to look at another more complete classification: OS1, OS2, OM1, OM2, OM3 and the most recent OM4.
Singlemode fibers (OS) are classified by their maximum attenuation :
Multimode fibers (OM) have a bandwidth OFL from 200 MHz/km for OM1 fibers to 3500 MHz/km for OM4 fibers depending on fiber bandwidth. The specification of them are listed in the following form:
|Fiber Optic Category||Mode||Core Diameter||Wavelength||Modal Bandwidth||Cable jacket Color|
|OM1||multimode||62.5 um||850 nm
|OM2||multimode||50 um||850 nm
|OM3||multimode||50 um||850 nm
|OM4||multimode||50 um||850 nm
|OS1||single-mode||9 um||1310 nm
In summary, as the technology in the field of network is developing rapidly, fiber optics seem to become the trend for the increasing demand of the market. However, whether to choose twisted pair cables, coaxial cables or fiber optic cables still depends heavily on applications, which is subject to the cost, transmission distance and performance. These three kinds of cables are actually complementary with each other in many ways.
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