Why Choose the Shielded Cabling System

Shielded VS. Unshielded

In Network Cabling system at all levels, there are two main technical types: Shielded and Unshielded cabling systems. Since the earliest fabric cabling standards since its establishment types on these two technologies are widespread in the market. Germany, Australia, Switzerland and France in the first preference or relatively shielded cabling system, while in other parts of the world, the more popular non-shielded cabling system and will soon be adopted. Both shielded and unshielded gigabit transfer rate to meet the requirements, but when the transmission rate up to Gigabit or even higher, the shield system to support the stability of the advantages of the high frequency transmission becomes very apparent.

What is the function of shielded?
F/UTP

F/UTP cable shielding structure is four pairs of wires in the data cable outside the contractor a layer of aluminum foil shielded, this layer of shielding can be reduced to a great extent the total package:

1. This is the root of the signal transmission cable radiated interference signals on the impact of adjacent data cable (for example: the same bundle of cables in the adjacent data cable).

2. Interference from other data cable or other interference source signal for this cable.

3. For a high quality data transmission system, which is significant in two kinds of effects. If the external interference signal is strong enough it will happen with the normal transmission signal stack a plus, resulting in reduced transmission performance even the entire system can not work properly.

S/FTP

S/FTP structure in addition to the total package of braided foil shield, Twisted Pair Cable is respectively in each pair with a layer of aluminum foil shield to protect the transmission signal does not interfere with each other, so near-end crosstalk attenuation (NEXT)performance dramatically.  NEXT better performance means higher SNR and better transmission quality and faster system output. S/FTP shielded cables NEXT excellent structural performance of other cables (such as non-shielded U/UTP) can not be compared, therefore, ISO11801 on the Cat 7 (600MHz) and Cat 7a  (1000MHz) only provides the S/FTP cable structure, U/UTP cannot meet.

10GBase-T make data cable is facing new problems: Alien Crosstalk

2006 Copper Gigabit Ethernet applications published the proposed new standard transport protocols 10GBASE-T compared to 1000Base-T, its transmission rate increased 10 times. 1000BASE-T copper cabling required parameters (Attenuation, NEXT, Return Loss, etc.) the bandwidth required to reach 1-100MHz, with UTP Cat 5e (Class D) cabling system to meet requirements. 10GBASE-T cabling channel requirements of all component parameters have to be up to 500MHz bandwidth, which requires copper to reach at least Cat.6A (Class Ea) or higher level.

Along with the development of 10GBASE-T, external noise problems become more evident, resulting in a specification for external noise to be used to assess in the same bundle of cables, the interaction between different cables. This is what we call Alien Crosstalk. Alien Crosstalk will increase with the increase of frequency. Worse, 10GBASE-T confronted with external noise, will not be able to “adaptive” to lower the rate at which the network may be subsequently face paralysis. Therefore, to support 10GBASE-T cabling system application, the ability to resist alien crosstalk is vital.

  • Since 10GBASE-T high transmission frequencies and complex coding method is very sensitive to the external noise.
  • Shielding system excellent coupling atttenuation performance makes it naturally have to resist alien crosstalk.
  • The unshielded system against alien crosstalk is usually only on the performance of 0dB.
  • Shielding system in the design is completely satisfy the application of 10G.
The installation of 10GBase-T: U/UTP VS. FTP

Unshielded system: As far as possible away from power cable during installation; Different applications (1Gb/s and 10Gb/s) in the same pipeline transmission will cause the external crosstalk.

Shielding system: With the power cable can be reduced separation distance; Allow different applications (1 Gb / s and 10 Gb / s) in the same pipeline transmission; Does not need additional external crosstalk test field.

The separation distance between the data cable and power cable

In EN50174 standard defines the content of different coupling attenuation value level of data cable, respectively, from A (low coupling attenuation, worse) to D (high coupling attenuation, good) four levels.

Installers need to know which cable separated levels to determine the choice of the data requirements of the standard cable with power cable between the minimum separation distance. Data cable coupling attenuation higher the value and power cables minimum separation distance between the smaller.

Relative to the shielded cable, the unshielded (U/UTP) separation distance between cable and power cable to further. In the implementation of the project, if need the data cable and power cable isolation far distance, we need a bigger size pipe/bridge, or even additional bridge, doing this will no doubt have higher cost, sometimes limited to the bridge installation space. To make matters worse, these additional requirements often neglected or ignored, resulting in network system is the key point of interference.

Grounding

For shielded, unshielded systems and Fiber Optics Cable, all need to implement protective grounding. Because of the need to consider personal and equipment safety, therefore no matter adopt what kind of cabling system, the metal part of the system must be grounded.

For the shielding system, also need to implement the functional ground. Grounded shielding system functions with respect to the implementation of non-shielded systems only difference is that when you install the module connector and the cable shielding mask area area connected.

Overview

Shielding system relative to the unshielded system has been greatly improved EMC performance. For Gigabit Ethernet applications, shielding against external interference effects is essential, and shielded cabling system had to meet the standards in the design of anti-alien crosstalk (A-XT) requirements, can effectively prevent the cable from the adjacent between the external crosstalk.

The Core Technology Of WIRING

1. High-precision Optical Time Domain Reflectometer(ODTR)

OTDR technology through sending a test signal in the measured line while monitoring signal in the line of reflection phase and intensity. If the signal through the cable encounter mutation of an impedance, part or all of the signals will be reflected back, the reflected signal delay, size and polarity indicate the discontinuity position and feature of the special impedance in the cable.

2. Split Pairs

UTP(Unshielded Twisted Pair) cable is two insulated Copper Wires twisted together to each other by a certain density, which reduces the degree of signal interference, each wire in the transmission of radiation waves are offset by radio waves from the other line.

The so-called split pairs is the original two pairs are opened and yet again to reform a new pair. Because when this failure occurs, the end-to-end connectivity is good, so use a multimeter or hand tool such tools can not check it out. Only with a dedicated cable tester to check it out. Since crosstalk on the related lines of no kink, so online pairs when signal through will produce a high near-end crosstalk (NEXT).

Split pairs normally also be used, but often crosstalk index is large, only to run in the 10M application, can not achieve the 100M application.

3. The Standard Twisted Pair Terminations

Twisted pair eight lines are inserted into the plug (or termination) according to the standard. There are two termination criteria: EIA/TIA T568A/T568B, no essential difference between them, but the difference between color. The natural problem of termination is to ensure that: 1, 2 are a pair; 3, 6 are a pair; 4, 5 are a pair; 7, 8 are a pair. Note: Do not one cable end with T568A, but the other end with T568B. The mix use of T568A/T568B is a special connection method of cross connection. Projects more use T568B wire method.

In Ethernet, Pin1, Pin2 is a twisted pair responsible for network data transmission, Pin3, pin6 is a twisted pair responsible for network data reception, so 1, 2 a pair, 3, 6 a pair, 4, 5 a pair, 7, 8 a pair, it is a must, and not 1, 2, 3, 4, 5, 6, 7, 8 pairs, so called split pairs, will lead to serious signal leakage.

4. Wire Map

Ware Map: This is to confirm the integrity of link connection, mainly to check each pair of 8-core Twisted Pair Cable whether meets the required standards EIA/TIA- 568A/568B, whether the wire at both ends of cable is matching. If wrong, there are five cases include open circuit, short circuit, crossed pairs, reversed pair and split pairs.

● Open circuit: refers to the phenomenon of line off, generally due to bad crystal head cable connection, common with the cable test equipment can locate the fault point.

● Short circuit: refers to one or more wires touch each other in a metal core, resulting in a short circuit.

● Crossed pairs: refers to wire at both ends error in the routing process, which is one end with 568A and the other end with the 568B, usually such wire method used in network equipments level, or network cards connection, but as a general wiring to say, as long as the two ends of the wire method consistent, as for the module wire method can refer to the color above.

● Reversed pairs: this error is due to both ends of a pair line connected to the positive and negative error, is generally believed that the odd line number for the positive electrode, the even line as the negative electrode, for example, 568B Pin1 orange white lines to the first pair of positive, Pin2 Orange Line is negative, it can form a direct current loop, reverse connection is positive and negative confused in the same pair line.

● Split pairs: this is one of the common wire error, which is not strictly comply with wire standard, it is specified in the standard that 1, 2 is the first pair, 3, 6, is the second pair, if 3, 4 into the second pair will cause large signal leakage, which produces NEXT (near end crosstalk), this will cause the user’s Internet difficulties or indirect interrupts, especially in the 1000Mbps network it is particularly obvious.

How To Purchase Twisted Pair Cable

Twisted Pair Cable is composed of 4 sets mutually intertwined wire wrapped in a layer of insulation coat and composition. The reason to be entangled with each other, because when a current in the wire (in fact, the data stream) when the fields are generated by, and the positive and negative signal line around the two resulting positive and negative magnetic fields will cancel each other out, to reduce signal interference.

Category 5e or Category 6

In accordance with the electrical properties of the different twisted pair can be divided into cat 3, cat 5, cat 5e, cat 6 and Cat 7 Twisted Pair Cables. Different categories of twisted pair cable the price is large difference, and the application is also very different.

In addition to traditional voice systems still use cat 3 twisted pair cable, the network cabling are now largely used cat 5e or cat 6 unshielded twisted pair. Cat 5 unshielded twisted pair, although still can support 1000Base-T, but because of the price is almost the same with cat 5e unshielded twisted pair, therefore, has been gradually fading cabling market.

Although the cat 6 unshielded twisted pair the price is higher, but due to cat 5e cabling system has a very good compatibility, and can be very good support 1000Base-T, it is slowly becoming the darling of cabling. Cat 7 shielded twisted pair is a brand new cabling system, while the perfor-mance is excellent, but because the price is expensive. Construction products less complex alternative, so rarely used in the cabling project.

Cat 6 unshielded twisted pair can be very good support Gigabit Ethernet, and to achieve 100m transmission distance. Therefore, the cat 6 cabling system has been widely used sub-server room cabling, and to retain the ability to upgrade to Gigabit Ethernet horizontal cabling. According to international cabling standards ISO11801, cabling system life expectancy of at least 10 years. As a long-term capital investment, cabling should take full account of the potential demand and network cabling system development, therefore, the availability of funds under the conditions recommended to choose cat 6 building cabling system products.

How to buy twisted pair cable

1. See packing and printing quality. Carefully check the cable box, the packaging is intact, fake in this regard province to province, so the packaging can determine the quality of the user’s first impression. Authentic twisted pair cable of packaging cartons, from the material quality of a material to the printed word should be quite good, stiff cardboard sharp edges. And many manufacturers are still labeled on the product packaging security signs.

2. See skin color and logo. Twisted pair cable insulation shall be printed on the place of origin, such as vendors, performance standards, product categories ( such as CAT5e C6t, etc.), long lines like the word mark.

3. Look twisting density. In order to reduce signal interference, each twisted pair cable are twisted in a counterclockwise direction to each other (also known as twisted around) is made different in the same cable pair is twisted with a different twisting degree. In addition to two pairs of insulated twisting copper conductors according to the requirements, the cable between wire pairs must be twisted counterclockwise. If twisting density does not meet technical requirements, will not match due to cable resistance, leading to more serious near-end crosstalk, thus shortening the transmission distance, reduce the transmission rate. If you find all pairs in the cable twisted around the same density, or wire twisted around the density does not meet the technical requirements, or twisted around the direction of the pair does not meet the requirements, can be determined to be counterfeit.

4. See cable colors. Peel twisted pair after the outer layer of the rubber, you can see the inside by the different colors of the four pairs eight thin, followed by orange, green, blue, brown, each pair of cables with a color cable and a mixing cable components. It should be noted that these colors definitely not subsequently infected with a dye to go, but the use of the corresponding plastic. No color, clear or dyed color cables, is certainly not true cable.

5. Look retardant case. In order to avoid high temperatures or fire resulting burning and damage the cable, twisted pair in addition to the outermost sheath layer should have good tensile properties, but also has flame retardancy.

Genuine cable sheath beneath the barbecue in the fireworks, and gradually melted deformed, but the skin won’t burn itself. If not flame retardant cable is certainly not genuine.

1. In most case can also be twisted by a finger touching the skin to do the initial judement. Fake cable to save costs, the use of inferior cable, feel sticky, there is a certain sense of stagnation, poor quality. True cable feel is really comfortable and the smooth skin.

2. Use hand to knead a pinch cable body, feel is should be full. Cables shall also be free to bend, to facilitate cabling. Taking intoo account the Network Cable in the cabling often need to bend, many regular vendors in the production of cable left gave the skin a certain stretch to ensure that the network cable is not damaged when bent. Therefore, hands pull the regular network cable, and found the skin has extensibility. Good quality cable designed to take into account ease of cabling, try to make it pliable, no matter how easy bending, but not easy to be broken. In order to make the twisted pair in moving not break cable, except for the outer protective layer of skin, internal copper also has a certain toughness. Copper neither too soft nor too hard, too soft or too hard enough to show that the purity of the copper, it will seriously affect the electrical performance of the network cable.

If the application needs to consider the network in the future, in theory, should install the most advanced cabling products, because the cable is often difficult to re-install the update replacement, basically, a cabling system to be applied at least 10 years as a standard to support 4-5 generations of network equipment performance updates, if the future of network equipment better cable is needed to improve data speeds.

Then, with Cat 6 Cables instead of cat 5e cable is inevitable, but these cables re-established engineering is very expensive, so even though cat 6 products price relatively in cat 5e products are a bit expensive, but in order to reduce the network upgrade in the future, cat 6 products are still worth considering.

The Difference Between Fiber Optic Cable, Twisted Pair and Cable

In network hardware, as well as a class can not be ignored is the network transmission medium, usually referred to as a network cable. Common cable of thin twisted pair, fiber optic cable, coaxial cable, and coarse coaxial cable.

Fiber Optic Cable

The fiber optic cable is a new generation of transmission media, compared with copper media, fiber, both in terms of safety, reliability, or network performance has been greatly improved. In addition, the bandwidth of the optical fiber transmission far beyond copper cable, and its support maxium connection distance of more than two kilometers, is the inevitable choice for the formation of large-scale networks. Because the fiber optic cable has good resistance to electromagnetic interference, confidentiality, speed and transmission capacity, so its price is also more expensive at home, rarely used. Now more common with the two different types of optical fiber, respectively, is a single-mode optical fiber and multi-mode optical fiber (the so-called “mode” refers to a beam of light entering the fiber at a certain angle). Multimode fiber is generally used in the same office or relatively close area network connection. And a higher quality of the data of the single-mode optical fiber transmission, the transmission distance is longer, typically is used to connect the office or between geographically dispersed broader network. If the use of fiber optic cable as a network transmission medium, the need to increase the optical end transceiver equipment, the cost of inputs greater, less used in general applications.

Twisted Pair

Twisted pair cable is a flexible communications cable, containing a pair of insulated copper wire, it’s cheap, it is widely used, such as common telephone line.Depending on the maximum transfer rate, twisted pair can be divided into three categories, Category 5 and Category 5 super. Rate of 3 twisted pair to 10mb/s class of up to 100mb/s, while the ultra category up to 155mb/s or more, may be suitable for the future multimedia data transmission needs, it is recommended that a Category 5 or Category 5 super double standed wire. Twisted pair can also be divided into a shielded twisted pair (STP) and unshielded twisted pair (UTP). STP twisted pair, although the rate is lower (only 4mb/s), but the anti-interference ratio utp twisted pair, so the price should be a lot more expensive type of twisted pair cheap a few dollars a meter, it may more than a dozen yuan to buy one meter. In contrast, utp twisted pair price is generally about one meter, relatively low. In addition, used the 10m and 100m popular unshielded twisted pair is called 10base-t and 100base-t, we can often see in the market. Also supporting the use of rj45 crystal head and twisted pair for making twisted pair NIC rj45 interface connector, its quality is directly related to the stability of the entire network, and can not be ignored.

Coaxial Cable

Coaxial cable transmission medium is more familiar with a lot of friends, it is by layers of insulated wire wrapped around the central copper conductor cable, its most important feature is the anti-jamming capability, stable transmission of data, and the price is cheap, so, once widely used, such as closed circuit television lines. Previously coaxial cable with more, mainly because coaxial cable bus structure composed of network costs lower, but the single cable damage may lead to paralysis of the entire network, maintenance difficult, and this is its biggest drawbacks. Ethernet applications of coaxial cable into the thick coaxial cable (10base5) and thin coaxial cable (10base2) two kinds. Now not thick coaxial, thin coaxial cable market. The thin coaxial line general market price a few dollars a meter, not too expensive. Coaxial cable is used to and bnc head connected coaxial cable to sell on the market are generally and bnc head connection of the finished product, we can directly use.

Article source: http://www.fs.com/blog