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Introduction

A Study on Effect of AC Power Lines on UTP cable: A Thesis Page 2

Chapter 1: Introduction

The concept of global village in today’s world is based on computer

networking system. Today, we can never imagine our lives without computer

networking. In computer networking system, data communication or the process

of sending data from one location to another location is done electronically.

Again, we can never imagine our surroundings at homes or offices without

the installation of AC power lines. Because, we all use different electronic and

electrical appliances and instruments for the requirements of our modern life –

styles. Modern life-styles and business world heavily depend upon electrical

and electronic services utilizing different electrical/electronic instruments/

devices. For the operation of these electrical/electronic instruments/devices,

installation of power lines and power supplies are needed. This implies that

today we are surrounded by power lines at our homes, schools/colleges and

offices for smooth running of our daily lives and services. Again, for computer

networking which has become a fundamental fact of today’s life, installation of

networking cable is also essential. Therefore, at our homes or office buildings

there are two types of cable installations- one is power line or power cable

installation and the other is network cable installation.

Currently, Unshielded Twisted Pair (UTP) cable is the most popularly used

copper-based cable for networking supporting 10G Ethernet. Ethernet is the

most commonly used LAN technology. Although UTP is widely used for

networking, the main disadvantage with UTP cable is that it is the most

sensitive cable to Electromagnetic Interference (EMI) than any other networking

Introduction


cables, such as shielded twisted pair (STP) or co-axial cables. The reason

behind it is UTP cable offers low cost, ease of installation and supports high

speed of data transmission with high bandwidth, low attenuation, low cross-talk.

Electromagnetic Interference (EMI) is an undesirable phenomenon, which

creates electromagnetic disturbance in the response of electrical or electronic

systems. EMI degrades the performance of a system due to the

electromagnetic fields making up an electromagnetic environment. Since all

electric signals are electromagnetic waves, we are living in an electromagnetic

environment. Effect of electromagnetic interference or noise has become an

exceptionally crucial issue in the design of modern electronic system. Some of

the very common examples of EMI sources are-different types of lightings,

electric hand drill, Transceiver set, Fluorescent light, Microwave oven,

generators, elevator motors, different medical equipments. Generally most

electronic equipments are associated with EMI filters on the front end of their

power supplies, which are used to prevent interference or noise conducted from

power lines through the power supplies. But noise can couple into the system

through the metallic enclosures or through the data lines. UTP cable is very

much prone to electromagnetic interference. The probability to be effected by

EMI becomes high, when the cable run close to the source of EMI or grounding

system is inadequate. The EMI from the source can go through the unshielded

cable very easily and can affect the data transmission quality, which may result

in shutting down the communication system also. Shielded cables are basically

designed to protect the signal transmission through it from sources of EMI

powerful enough to generate Electromagnetic Interference. The basic functions

Introduction


of the shield are to prevent signal loss due to interference and to prevent

electromagnetic radiations to interfere with devices. In modern day building

structure, some very basic sources of EMI are found close to communication

cables. It is not always possible to avoid networking cables from running close

to EMI affected area produced by those sources. In this case, shielded cables

are advised to use instead of unshielded cables. Shielded cables are costlier

than unshielded cables. Therefore, if UTP is the first choice to be used by the

users, the first point to note is to maintain an appreciable separation gap

between UTP cable and sources of EMI to avoid interference, which may not be

always possible. Then the only option is to use shielded cables.

High speed data transmission supported by modern computer systems is

getting faster and faster day by day. Therefore, design of computer systems are

becoming harder and harder. During the process of computer design the things

to be considered are power dissipation, data transmission speed, memory

capacity and off course, protection against effect of electromagnetic

interference which may result in even failure of computer operations for

excessive effect of EMI. During the last 15-20 years, there has been a rapid

increase in the number of electromagnetic emissive sources. Our life is quite

comfortable with the uses of cellular phones, digital pagers, fax machine and

different medical instruments. Power line, which we found at our surroundings

for the operations of different electronic and electrical systems/ devices, is a

source of Electromagnetic Interference (EMI) also. Distance between the EMI

source and the victim plays an important role in the intensity of effects of EMI.

During installation of unshielded cable with the installation of AC power lines

Introduction


within the same building structure, careful consideration has to be taken

regarding all factors, which may affect the data transmission through the

networking cable.

1.1 Networking

When two or more individual systems with data are interconnected to share

services and to interact with each other by means of a shared communication

link, a network is created. For example, suppose three computers are

connected together with a network cable and each of them are also connected

to a laser printer to use. Therefore, they create a network and each of them are

a part of the network. The size of a network depends upon the need and the

necessity of the users. To form networks, all networks must have the following

[1]:

• Data to share

• A physical pathway, called transmission medium

• Rules of communication, called protocols

1.1.1 Advantages of networking

The following are the advantages of computer networks:

• Sharing of files, resources and programs.

• Enhanced Communication between users through e-mail and groupware

applications.

• Ease of Connectivity of computers throughout the whole world

Introduction


• Improved price and performance ratios because of rapidly decreasing

cost of personal computers and related hardware.

• Improved person-to-person communication through E-mail, On-line

discussion and video conferencing.

1.1.2 Disadvantages of networking

Computer networking has some disadvantages also. They include:

• Lack of data security and privacy because of unauthorized users or

multiuser.

• High-speed network connection is expensive and has complex wiring.

• New developed reliable network software are complicated and costly.

• Crashing of the server on a server-based network because of irregular

backups.

1.1.3 Basic Components of Networking

The key Network Components with examples are:

• Media: Examples are- Twisted pair wire, coaxial cable, fiber optic cable,

microwave satellites, Cellular radio and transceivers.

• Processors: Examples are-Modems, multiplexers, concentrators,

routers, bridges, Gateways, Front-end processors and client and server

computers.

• Software: Examples are- Communication software, network operating

system, Netware, Point-to-Point Protocol (PPP), Post Office Protocol

Introduction


(POP), Simple Mail Transfer Protocol (SMTP), Internet Explorer or

Netscape Navigator and middleware.

• Channels: Examples are -Analog/ digital, switched/non-switched,

circuit/massage/Packet switching, simplex / duplex,

synchronous/asynchronous.

• Topology: Examples are- Bus, star, ring, mesh and Ethernet.

• Architecture: Examples are- OSI, Institute of Electrical and Electric

Appliances (IEEE), Integrated Services Digital Network (ISDN) and

Public Switched Telephone Network (PSTN).

1.1.4 Network Topology

In a network, each computer or device, say printer is called a node.

Network topology defines how nodes are connected to each other. It is the

geometrical arrangement of nodes and cable links in a LAN [1, 2]. Following are

the different network topologies:

• Bus Network

Bus network provides the connectivity of each computer to other computers

through a single communication cable, so that every computer can directly

communicate with every other computer or device in the network (fig 1.1).

Fig 1.1: Bus Network.

computer computer

computer computer

Introduction


• Ring Network

In a ring network, a single communication cable is used to connect several

computers or devices in a closed loop (fig 1.2).

Fig 1.2: Ring Network

• Star Network

In a star network, all the devices or computers are connected to one

common central computer. Information exchange is done by first sending to the

central computer from the source computer, which in turn sends them to the

destination computer (fig 1.3).

Fig 1.3: Star Network

computer

computer computer

computer

computer

computer

computer

central

computer

computer

computer

Introduction


• Tree Network

In a tree network, all the computers and devices are linked in a hierarchical

fashion as shown in the fig 1.4.

Fig 1.4: Tree Network

• Mesh Network

In a mesh network, every computer or device has point-to-point connections

between them (fig 1.5).

Fig 1.5: Mesh Network

computer

computer computer

computer computer

computer

Mainframe

computer

computer computer

computer computer computer computer

Introduction


1.1.5 Network Protocols

A network protocol is a set of rules and standards for communication

between computers [1]. Without protocols, the computers can only be

connected but there will be no communication between them. Because,

protocols govern the format of data, the timing, sequencing and error control.

1.1.6 Network Models

A network model is a computer network architecture. Network models are

classified into three categories:

• The peer-to-peer network where, each computer of a group is equal

in terms of authority and usage (fig 1.6). Each computer is called a

peer, which can share its resources on the net work. Each peer is both

a client and a server. There is no specialized servers exist.

Fig 1.6: Peer-to-peer network.

• The client/server network, where communication takes place

between the client and the server computers (fig 1.7). The client

requests for services and the server responds to these requests from

the client.

peer

peer

peer peer

Introduction


.

Fig 1.7: Client/server network .

• The Hybrid Network, which is a combination of two or more networks

topologies. For example, several star LANs can be connected by a bus

or a ring, or a bus that connects several ring networks (fig1.8).

Combinations of server-based and peer-to-peer networking models

constitute many networking environments.

Fig 1.8: Hybrid network.

1.1.7 Hardware and Software of Networks

Different hardware and software are needed for establishment of a network.

The hardware includes the network interface card (NIC), networking cables and

HUB HUB

compute

r

computer compute

r

computer

compute compute

r

computer compute

r

server

client client client client

Introduction


network devices. The software includes the protocols and the network operating

system.

1.1.8 The Network Interface Card (NIC)

A NIC is a device which is integrated into the system motherboard. It

enables a computer to send and receive data across the network by providing

an interface between the data bus and the networking medium. Every NIC has

a 48-bit long binary address called Media Access Control Address (MAC) and

which is used uniquely to identify each node of a computer.

1.1.9 Networking Devices

Different networking devices are

• Hubs

A hub is used to connect multiple computers together. A hub has a number

of ports and the different computers can be connected to these ports to form a

network (fig1.9).

Fig: 1.9: Hub.

HUB

computer

computer

computer

computer

Introduction


• Switches

A switch is used to join multiple computers in a network. A switch and a hub

are identical, but a switch is much more efficient. Switches are more suitable for

use in areas of high network traffic (fig1.10).

Fig 1.10: Switch

• Repeaters

A repeater is a networking hardware device, which regenerates the

transmitted attenuated information carrying signal to its original strength.

• Bridges

A bridge is a network hardware device, whose function is to regenerate the

weak signals it receives and to check the physical address of the source and

destination nodes (fig 1.11).

Fig 1.11: Bridge

SWITCH

computer computer

computer computer

Bridge

computer computer computer


Introduction


• Routers

A router (fig1.12) is used to connect LANS and WANs on the internet. It

contains a routing table which takes decision about the route of a data packet.

The router, when receives a data packet from a source network, checks for the

Internet Protocol address of the destination and transfers the data packet to its

appropriate destination.

Fig 1.12: Router.

1.1.10 Networking Cables

Networking cables are the transmission media which carry data from a

source to the destination. The data is transmitted though the networking cables

in the form of electrical signals or optical signals. Different types of networking

cables are:

* The twisted pair cable

* The coaxial cable

* The fiber optical cable

1.1.11 Types of Networks

The different types of network available are: LAN, WAN and MAN.

Network 1 Router

Network 2

Network 3

Introduction


• Local Area Network (LAN)

A LAN is used to connect two or more computers within a small area [1, 2].

The area may be a room, an office building or a campus. The range of a LAN is

limited to a few kilometers only. Use of LAN enables the users to have a shared

access to devices and applications, file exchange between connected users

and communication between users. Main benefit of a LAN is that it reduces

hardware and software costs because users can share several computers and

peripheral devices.

A LAN generally consists of two or more computers, different peripheral

devices like modems, printers, plotters etc, networking cables, required

software for the operation of the computers and a plug-in board to handle the

data transmissions.

Characteristics of LAN are:

• high speed data transfer

• limited range

• less expensive technology than MAN and WAN.

Although LAN works over limited distance, it allows a large number and a

variety of computing devices to exchange information among them at high

speeds. The number of computers in LAN varies widely from small LANs to

large LANs. A small LAN can connect 2 to 25 computers while a large LAN can

connect more than 10,000 computers. The data transmission rate for LAN

technologies is up to 10Gbit/s.

Introduction


• Wide Area Network (WAN)

A WAN is used to connect computers with communication facilities covering

a wide geographical area [1, 2]. WAN connects different metropolitans,

countries and national boundaries. WANs can be interconnected with LANs. A

WAN connection may be entirely within a state or country or it may have

interconnection around the world.

Different available Protocols for WAN are X.25, TCP/IP, Frame Relay. The

transfer rate of these protocols is around 1Mbit/s or less. WAN is involved with a

public telecommunication authority. The use of WAN is limited by the large

organizations and government agencies.

Characteristics of WAN are:

• WAN interconnects multiple LANs, covers an unlimited geographical

area, but susceptible to errors due to the distances involved.

• WAN technology is expensive, more sophisticated and complex than

LANs.

Categories of WANs are:

• Enterprise WANs: Used to connect all LANs of a single organization

those are located at great distances.

• Global WANs: Used to interconnect the networks of several corporations

and organizations.

Internet is the most common example of WAN.

Introduction


• Metropolitan Area Network (MAN)

MANs technology is similar to LAN but it is a bigger version of LAN [1, 2].

Its network coverage is between LAN and WAN. MAN generally connects two

or more LANs or Campus Area Networks (CANs). MAN acts as a backbone to

connect several LANs of an organization.

Apart from these three main types of networks namely, some other types of

networks are also available. They are Personal Area Network (PAN), Campus

Area Network (CAN), Global Area Network (GAN), Value Added Network

(VAN), Virtual Private Network (VPN), Wireless /Mobile Network.

1.1.12 LAN Technologies

Various existing LAN technologies to help to establish LAN are Ethernet,

Token Ring, Token Bus and FDDI.

• Ethernet

Today, the most widely accepted and commonly used LAN technology is

Ethernet [1, 3]. Ethernet is developed by DIX (Dec, Intel and Xerox corporation)

and is a registered trademark name with Xerox corporation. Ethernet is

standardized as IEEE 802.3. Ethernet transmission data rate is million bits per

second or Mbps. Ethernet has gone through four generations based on the

speed of data transfer. They are: Standard Ethernet, Fast Ethernet, Gigabit

Ethernet and Ten-Gigabit Ethernet.

Introduction


Standard Ethernet

The data transfer rate of Standard Ethernet is 10Mbps. The original

Standard Ethernet is divided into following types:

• 10Base5: Thick Ethernet or Thicknet .

• 10Base2: Thin Ethernet or Chipernet. It is more economical than

10Base5.

• 10Base-T: Twisted Pair Ethernet. It grows in popularity because of its

reliability and flexibility and easy installation than the previous two.

• 10Base-F: Fiber Ethernet. It consists of three types, namely, 10BaseFL,

10BaseFB and 10BaseFP.

The following table1.1 shows Standard Ethernet implementations with

media and lengths.

Table 1.1: Standard Ethernet implementations

Characteristics 10Base5 10Base2 10Base-T 10Base-F

Media Thick coaxial

cable

Thin coaxial

cable

2 UTP 2 Fiber

Maximum

length

500 m 185 m 100 m 2000m

Fast Ethernet

Fast Ethernet transfers data 10 times faster than the Standard Ethernet. Its

data transfer rate is 100Mbps. Fast Ethernet is divided into following types:

Introduction


• 100BaseT4: It uses all the four pairs of wires in the cable. It was the first

type to be introduced as of Fast Ethernet.

• 100BaseTX: It uses two pairs of twisted pairs of cable. It is generally

used in office networks.

• 100BaseFX: It uses two pairs of optical fiber cable. It is generally used

as a backbone for computer networks.

The following table1.2 shows Fast Ethernet implementations with media and

lengths.

Table 1.2: Fast Ethernet implementations

Gigabit Ethernet

The data transfer rate of the Gigabit Ethernet is 1Gbps or 1000Mbps which

is 100 times faster than the original Standard Ethernet. Gigabit Ethernet is

divided into following different types:

• 1000Base-T: Refers to a standard type of four-wire implementation of

Gigabit Ethernet .Uses UTP CAT5 cable, but CAT5e or CAT6 is

preferred.

Characteristics 100Base-T4 100Base-TX 100Base-FX

Media Cat 4 UTP Optical Fiber Cat 5 UTP or STP

Number of wires 4 2 2

Maximum length 100m 100m 100m

Introduction


• 1000Base-SX: Refers to a type of Gigabit Ethernet using optical fiber. It

is a short wave two-wire implementation.

• 1000Base-LX: Refers to a type of Gigabit Ethernet using optical fiber. It

is a long wave two-wire implementation.

• 1000Base-CX: Refers to a type of Gigabit Ethernet using STP cable. It is

a two wire implementation.

The following table 1.3 shows Gigabit Ethernet implementations with media

and lengths.

Table 1.3: Gigabit Ethernet implementations

Ten-Gigabit Ethernet

Ten-Gigabit Ethernet is called as Standard 802.3ae created by IEEE

committee. It is designed to upgrade the data rate to 10Gbps. It is designed

Characteristics 1000Base-T 1000Base-

SX

1000Base-

LX

1000Base-

CX

Media Cat 5 UTP Fiber short

wave

Fiber long

wave

STP

Number of

wires

4 2 2 2

Maximum

length

100m 550m 5000m 25m

Introduction


using fiber optic cable over long distances. The most common implementations

are: 10GBase-S, 10GBase-L and 10GBase-E.

The following table 1.4 shows Ten-Gigabit Ethernet implementations with

media and lengths.

Table1.4: Ten-Gigabit Ethernet implementations.

• Token Ring

Token Ring is a LAN technology based on ring topology (fig1.13). It is

developed by International Business Machines (IBM) and is standardized as

IEEE 802.5. Token Ring transfers data at a rate from 4Mbps to 16Mbps. It uses

UTP cable and two of four pairs of cable wires.

• Token Bus

Token Bus is another type of LAN technology based on bus topology (fig

1.14). It is standardized as IEEE802.4 and is designed for large organizations.

Characteristics 10GBase-S 10GBase-L 10GBase-E

Media Short-wave

850-nm

multimode

Long-wave

1310-nm

Single mode

Extended 1550-nm

single mode

Maximum

length

300 m 10 km 40 km

Introduction


Fig 1.13: Token Ring

Fig 1.14: Token Bus

• Fiber Distributed Data Interface

Fiber Distributed Data Interface (FDDI) is a standard LAN technology using

fiber optic cable. Its data transfer rate is 100Mbps. FDDI is based on the ring

topology. It uses a dual ring model of a primary ring and a secondary ring. The

flow of data in primary ring and secondary ring are in opposite directions.


computer computer


computer computer

computer

Token ring

Introduction


1.1.13 Basic model of Ethernet

The fig 1.15 shows a very simple model of Ethernet network design for a

small office consisting of UTP cabling that runs from a file server to several

workstations with a printer. For UTP cabling the combined cable length

connecting workstations and printer should not exceed 100 meters.

Fig 1.15: A simple Ethernet network with a printer.

1.2 Cabling

Cabling can be classified into following types [4]:

• Campus cabling: Campus cabling is used to connect and integrate the

network within an overall area containing more than one building.

Campus cabling is usually optical fiber based and connects the main

wiring closets on different buildings.

• Riser/Backbone cabling: Riser or backbone cabling uses screened or

unscreened pair cables and used for data and telephones. It connects


printer

computer computer

S

E

R

V

E

R

Introduction


the house central wiring closet to wiring closets on different building

floors.

• Horizontal cables: Horizontal twisted pair (UTP and FTP) cables

provide the communication link between and into specific work areas for

high speed networks. These cables can be used in lengths of up to 90

meters. 24AWG is the most commonly used thickness for fixed wiring.

• Work area cabling: High performance flexible work area cables are

available unscreened or Foil Screened and used for localized linking

from a wall connection to networked equipment.

• Patch cables: Patch cables are generally available unscreened or foil

screened. These cables are used to interconnect different

communication equipment.

1.2.1Types of Networking Cables

Data with information moves from one network device to another device

through networking cable. Networking cable is the transmission medium to

transmit data from one end to another end. Different types of cables are

available, which are commonly used with LANs. Selection of the type of cable

for a network depends upon the network’s topology, size, protocol and

expenditure also.

Networking cables are broadly divided into two types – copper and fiber.

Different types of networking cables offer different levels of performance. They

are:

Introduction


• Twisted Pair (TP) cable

• Co-axial cable

• Fiber Optic cable

Twisted Pair (TP) and co-axial cables are copper based cables. Copper

cabling has been used for decades to provide communication. Copper is a good

conductor of electricity. The signals through copper cable are electric signals.

Fiber optic cables are made of glass or plastic. The signals through fiber cables

are optical signals.

1.2.2 Twisted Pair Cables

A Twisted Pair (TP) consists of two copper wires, twisted together, each

with its own plastic insulation [4-8]. When electric current flows through a

copper wire, a small circular magnetic field is created around the wire. When

two current carrying wires of an electrical circuit are in close proximity, the two

magnetic fields are the exact opposite of each other. Hence they cancel each

other out. They also cancel out any outside magnetic fields. This cancellation

effect is enhanced when the two wires are twisted. Cable designers provide a

self-shielding technique against signal noise and cross-talk for wire pairs using

the cancellation effects together with twisting the wires. There are two types TP

cables. They are:

• Unshielded Twisted Pair (UTP) cable

• Shielded Twisted Pair (STP) cable.

Introduction


Unshielded Twisted Pair (UTP) Cabling

Types of UTP cable vary from telephone wire cable to extremely high speed

data supporting cable.UTP cable contains 8 wires, each 2 wires twisted

together into 4 pairs with a plastic jacket. The characteristic impedance of each

pair is 100 Ohms +/- 15%. Copper conductors of 24 gauge (0.5106-mm-

diameter) or optionally 22 gauge (0.6438 mm diameter) are used. Depending on

the number of twisted pairs and the application, each pair of UTP cable

performs different function.

EIA/TIA-568 standard specifies the electrical and physical requirements for

all types of cables. This standard also specifies the color coding, cable diameter

and electrical characteristics for cables. UTP cable must follow precise

specifications about the number of twists permitted per meter of cable.

Categories of UTP Cabling

EIA/TIA-586 has categorized 6 different categories of UTP cables by the

number of twists/foot. UTP cable with higher category number has more

twists/foot with better signal quality. Higher category number UTP cables are

technically more advanced than lower category number UTP cables. Table 1.5

shows different categories of UTP cable with their data rates, transmission

frequency and uses.

Introduction


Table1.5: Different categories of UTP cable

CAT5, CAT5e, CAT6 cables are popularly utilized for structured cabling

system in the modern building’s communication infrastructure. They can support

any voice, imaging and data applications. Performance of UTP cables are

guaranteed up to 100 meters between devices. Technically, the distance

limitation is 90 meters for structured cabling and a total of 10 meters for patch

cords on either end.

Category of UTP cable Data Rate, Frequency Uses

Category 1(CAT1) Up to 1Mbps Traditional Telephone and

ISDN-Modem

Category 2(CAT2) Up to 4Mbps Token Ring, ARCnet

Category 3(CAT3) Up to 10Mbps,16MHz Token Ring and 10Base-T

Category 4(CAT4) Up to 16 Mbps, 20MHz Token Ring

Category 5(CAT5) Up to 100 Mbps,100MHz Ethernet (10Mbps), Token

Ring (16Mbps) and

Fast Ethernet (100Mbps)

Category 5e(CAT5e) Up to 1000

Mbps,100MHz

Gigabit Ethernet

Category 6(CAT6) Up to

1000Mbps,250MHz

Gigabit Ethernet

Introduction


UTP Connector

The most common UTP connector is RJ-45 (RJ stands for registered jack)

[9]. It is an 8-position, 8-contact (8P8C) modulator plug and jack. The RJ-45 is a

keyed connector, meaning the connector can be inserted in only one way.

RJ-45 was originally patented in 1975 by Western Electric Company. Since

that time, RJ-45 has gone through many technical improvements to overcome

cross-talk as data rates have evolved from 16MHz for CAT3 to 500MHz for the

latest Category 6a standard.

Advantages of UTP cable

Advantages of UTP cable system are:

• UTP cable is a thin, flexible cable which is easy to string between walls.

Again, since UTP is small, it does not quickly fill up wiring ducts.

• UTP uses two wires rather than one for each signal. Use of two wires

allows the use of differential signaling. Differential signaling is more

immune to the effects of external electrical noise.

• In UTP cable, each pair is twisted. Twisting keeps the wires of a signal’s

pair as close as possible and hence periodically exposes the opposite

side of the pair to the noise which helps to cancel out the effects of

outside interference. Again, each pair has a different twist pitch and

therefore the pairs also appear twisted to each other which helps to

reduce cross talk between the pairs.

Introduction


• Since UTP cable is with no shielding, it reduces the cost, size and

installation time of the cable and connectors. It also eliminates the

possibility of ground loops.

Disadvantages of UTP cable

• UTP cable is more prone to electrical noise and interference than other

types of networking media.

• The distance between signal boosts is shorter for UTP than it is for

coaxial and fiber optic cable.

Shielded Twisted Pair (STP) Cable

STP is a version of the twisted pair cable created by IBM. It is an insulated

cable which includes bundled pairs wrapped in a foil shield. This type shielding

protects the cables from external electromagnetic interferences and crosstalk

[2, 3, 8]. STP is more difficult to install than UTP or coaxial cable.STP costs

more than UTP but is less expensive than thick coaxial cable or fiber optic

cable. The biggest difference between UTP and STP is the reduction of

interference of EMI provided by STP’s shielding. However, STP still suffers from

relatively low immunity from interference.

STP suffers from attenuation at a rate similar to UTP. Current technology

restricts the effective range of STP to 100 meters for supporting Fast Ethernet

(100 Base TX). But when used to support 10G Ethernet (1000 Base CX), the

effective range is limited to 25m only.

Introduction


New Generation Cabling

Category7 (Cat7) is the new generation cabling supporting 10G Ethernet

Standard [5]. Cat7 is also called SSTP (Shielded Screen Twisted Pair). It also

consists of 4pairs of twisted wires like UTP cable, each pair of wires is

individually wrapped in a helical metallic foil followed by a metallic foil shield in

addition to the outside sheath. Use of shielding reduces the effect of crosstalk

and supports a data rate up to 600MHz.

1.2.3 Co-axial cable

A coaxial cable consists of two concentric conductors. The inner conductor

is of solid copper, which is also called the core conductor. The outer conductor,

which serves as a second conductor, also serves as a shield against noise.

Between the two conductors, there is an insulating material and the whole cable

is covered with a cable jacket. The cover shields the cable from electromagnetic

interference as well as from physical danger [2, 3].

Coaxial cables bandwidth potential increases with the diameter of the inner

conductors. The cost of coaxial cable also increases with the diameter and

composition of the conductors. The cost of thin coaxial cable is less than UTP

and STP and the cost of thick coaxial cable is more than UTP and STP cable.

Coaxial cable suffers from high attenuation, but at a much lower rate than

twisted pair cables. While copper wire generally is a poor resistor to EMI, the

shielding provided by coaxial cable greatly reduces its effects.

Introduction


Categories of Co-axial Cables

The RG (radio government) ratings are used to categorize the co-axial

cables. Different RG ratings denote different set of physical specifications and

are used for different specialized function.

The following table 1.6 shows different categories of co-axial cable.

Table 1.6: Different categories of co-axial cable

Category Impedance Use

RG-59 75Ω Cable TV

RG-58 50Ω Thin Ethernet

(10Base 2)

RG-11 50Ω Thick Ethernet

(10 Base 5)

Co-axial Cable Connectors

The most common type co-axial cable connector is the BNC (Bayone-Neill-

Concelman) connector. There are 3 types of BNC connectors: the BNC

connectors, the BNC T connectors and the BNC terminator. For connection in

Ethernet networking, the BNC T connector is used.

1.2.4 Other copper cables

There are two main types of other copper cables. They are twinaxial

(“twinax”) and single –pair full-duplex [10].

Introduction


• Twinaxial copper cable

Twinaxial cable is similar to co-axial cable, but it has two parallel

conductors instead of one. It is an excellent choice for high speed data

transmission, but is relatively expensive. Twinaxial copper cable has not been

specified for deployment by the LAN or WAN standards bodies. It is used

primarily in mainframe computer rooms to connect various peripherals to the

computer or front-end processor. It provides a BER better than 10-18 according

to Cisco.

• Single-pair full duplex (POTS) cable

POTS cable is an UTP cable with full-duplex (simultaneous transmit and

receive) capability over a single pair of wires. Its use has been limited primarily

to analog voice-band service applications.

1.2.5 Fiber Optical Cable

In a fiber optical cable, the signal propagates in the form of light [1-3, 11] .It

has two concentric layers. The inner one is called the core, which is made up of

glass or plastic. The outer one is called the cladding, which is also made up of

glass or plastic, but it is less dense than the core. If the cladding is made of

glass, then there is also a plastic protective jacket.

The fiber optic cable has greater bandwidth than the copper cables. Due to

greater bandwidth, current technology supports data rates from 100 Mbps to

over 2Gbps, at distances from 2kms to 25kms. The supporting data rate of a

fiber optic system depends upon the composition of the used fiber, the mode

Introduction


supported by the system and the wavelength of the transmitted light. Optical

fiber transmits data at very high speed without errors. The transmitted signals

through the optical fiber are in the form of light. Therefore, they are not

subjected to electromagnetic interference (EMI). Fiber optic cables attenuate

much less than any copper cable. They have extremely low attenuation rates.

The transmitted light signal is well confined within the optical fiber cable, so no

loss or leakage of light signal occurs. Optical fiber cable is ideal for hazardous,

high voltage or eavesdropping-sensitive environments.

Advantages of Optical Fiber cables are:

• Low cost

• Small size and light weight

• Immunity to interference

• Signal security

• Electrical isolation

• Low transmission loss and wide bandwidth

There are two types of optical fibers: single mode fiber and multimode fiber.

Light signal can transverse the multimode fiber in many modes. But single

mode fiber allows only one mode of light propagation. The fiber diameter is 8.5

microns for single mode and 50 or 62.5 microns for multimode fiber. There are

three operating wavelengths for fiber-optic systems: 850nm, 1300nm or

1550nm. The transmitted light signals are commonly referred to by their

wavelength, expressed in nanometers (nm). Optical fiber signals are in the

Introduction


infrared portion of the spectrum, 850nm and 1300nm are the most common

wavelengths.

The following table 1.7 gives [13] the specifications for optical fiber cable

by type.

Table 1.7: Specifications for optical fiber cable

Installation of fiber optic cable is comparatively much more expensive than

any type of copper cable. Special care has to be taken to ensure that the light

path is not obstructed, at every fiber junction or connection. During installation,

the optical fiber should not be excessively stretched or bended.

1.2.6 Comparison between all types of cables

The following table 1.8 gives a comparison between all types of cable.

Cable Type Cable Type

Wavelength

Maximum

Attenuation

Minimum

Bandwidth

62.5 µm MM 850 nm 3.5 dB/km 500 MHz-km

1300 nm 1.5 dB/km 500 MHz-km

50 µm MM 850 nm 3.5 dB/km 160 MHz-km

1300 nm 1.5 dB/km 500 MHz-km

8.3 µm SM 1300 nm 1.0 dB/km n/a

1550 nm 0.5 dB/km n/a

Introduction


Table 1.8: A comparison between all types of cable

Cable

type

Cost Installation Capacity Range EMI

Co-axial

Thinnet

Less than

STP

Inexpensive/

Easy

10Mbps

typical

185 m Less

sensitive

than UTP

Co-axial

Thicknet

Greater than

STP,less than

fiber

Easy 10Mbps

typical

500 m Less

sensitive

than UTP

STP Greater than

UTP, less

Than thicknet

Fairly easy 16Mbps

typical to

500Mbps

100m

typical

Less

sensitive

than UTP

UTP Lowest Inexpensive/

Easy

10Mbps

typical to

100Mbps

100m

typical

Most

sensitive

Fiber

Optic

Highest Expensive/

difficult

100Mps

typical to as

high as

200,00Mbps

10s of

Km

Insensitive

Introduction


1.2.7 Cable Parameters of Interest

There are six parameters of interest for twisted-pair cable [10], which can be

determined from measurements using some special-purpose instruments. They

are namely:

• Z0, the characteristic impedance

• Length, the physical length of the cable

• Crosstalk, the coupling between adjacent pairs in the cable

• Resistance, the dc resistance of the copper conductors

• Attenuation, the signal loss at a specified frequency

• Wire map, the connector-to-connector wiring by pin numbers

The measurements for coaxial cable are the same for twisted-pair cable

except crosstalk and wire mapping.

1.2.8 Network Cabling Troubles

One of the most common source of problems on a network is the network

cabling. Cabling problems may result in many problems, such as disconnecting

workstations, slow network services, packet errors and unreliable data

transmission [3]. There are several things related to cabling structure resulting

problems on a network. Some of them are as follows:

• Cable length: If a cable segment is overly long, that is if a network

segment is extended beyond the IEEE specification, there will be

communication problems affecting all nodes on that segment.

• Cable type: Use of non-standard cabling.

Introduction


• Terminator: A defective or missing terminator on a network segment

may result like a network segment that is too long.

• Distance between Connectors: Two nearby workstations may face

network communication problems, if the distance between their

connectors is less than the minimum distance according to the IEEE

specifications.

• Grounding: Proper grounding is an important criteria during network

cabling installation. Lack of proper grounding may result in network

packet transmission with many Cyclic Redundancy (CRC) errors.

Grounding problems can be dangerous for network analysts and users

also.

• Cable impedance: Cable impedance must meet the required IEEE

specifications on Ethernet cable. Use of inexpensive or non standard

cable may cause data transmission problems.

• Opens and Shorts: An intermittent open or short on a cable segment

may cause intermittent problems on that segment causing network errors

and disconnection problems.

• RFI and EMI: Effect of RFI and EMI may result in noise on the data

transmission of network cable. This problem arises when the cable is run

close to the electrical field of an electric or electronic system.

• Connectors: A faulty connector may create problems causing a short or

open on the cable.

Introduction


1.2.9 Network Troubleshooting Equipments

Network troubleshooting equipments help to find the network problems and

its solutions. Some of the commonly used network test equipments are listed

below:

• Voltmeter, multimeter and optical power meter

• Transceiver monitor

• Cable scanner

• MAU analyzer

• Time domain reflectometer

• Protocol analyzer

• Remote network monitoring

A voltmeter is used to measure the voltage on a network cable or to test

signal strength on any network equipment. The multimeter has both a voltmeter

and an ohm meter. Using multimeter, the cable resistance can also be

determined as well as the voltage. An optical power meter is used to measure

the signal strength on a fiber optic cable run.

Transceivers are small devices, which are a part of the Attachment Unit

Interface (AUI). The transceiver monitor is used to detect different transceiver

problems which are related to power, signal reception and collision handing.

Cable scanners are designed to test the different network cabling plants.

Cable scanner can provide more information than a voltmeter or a multimeter.

Introduction


Multimeters are able to indicate only the presence of a short or open circuit.

But scanners are able to show the location of problems also. Scanners can find

out whether the cable is too long for IEEE specifications or not. A scanner can

also indicate that whether the cable has radio frequency interference or

electromagnetic interference or not.

A MAU analyzer functions similar to a cable scanner. It is used in Token

Ring networks.

A Time Domain Reflectometer (TDR) functions similar to an oscilloscope. It

can test various things of a network. They are line impedance, open, shorts,

electrical interference, cable distances and connector and terminator problems.

Protocol analyzers are the most comprehensive network monitoring

devices. They are expensive and contain software that is designed to interpret

specific protocol. Generally they are used in large network.

1.3 Current Trend of Cabling

1.3.1 Structured Cabling System

The term “Structured Cabling System” refers to all of the cabling and cabling

components installed in a logical, hierarchical way [4]. Previously, each of the

different data communications technology required its own type of wiring.

Today, structured cabling system which is a single wiring technology, can

support all the major existing data networking technologies. The design of

structured cabling is relatively independent of the used network, so that it can

be updated with a minimum of rework in future.

Introduction


Benefits of structured UTP cabling include:

• UTP cabling permits many communication protocols including voice,

data, CCTV video and control to reside in the same wire bundle.

• UTP cabling is a Color-coded cabling.

• UTP cable is less expensive than co-axial or fiber cable.

• UTP cable is physically smaller than co-axial and other types of cables

• UTP cabling is very easy media to install, terminate and reconfigure.

• A good properly installed UTP system gives better interference rejection

than co-axial cable system

1.3.2 Unshielded Twisted Pair Cabling

Unshielded Twisted Pair (UTP) cable is the most common cable used in

networking. Ethernet, the most common data networking standard utilizes UTP

cable. Despite of the disadvantage that UTP is the most sensitive cable to

Electromagnetic Interference (EMI) than any other type of cable, it grows in

popularity in networking world. Today, it is considered as the fastest copper

based medium for most of the major networking architectures. The reason

behind it is UTP cable offers low cost, ease of installation and supports high

speed of data transmission with high bandwidth, low attenuation, low cross-talk.

Therefore, today UTP is the most widely used networking cable for most of the

structured cabling systems. During installation of UTP cable, careful

considerations are taken to minimize the effect of EMI, by maintaining a proper

separation gap between UTP cabling and the possible EMI sources.

Introduction


UTP is a type of cable with twisted pairs of conductors and no shield [4-8].

Types of UTP cable vary from telephone wire cable to extremely high speed

data supporting cable. Alexander Graham Bell first used UTP cable in his

telephone system in 1881. The term “UTP” is specified in the EIA/TIA-568

Commercial Building Telecommunication Wiring Standard as ‘Unshielded

Twisted Pair’ cable. This standard specifies the electrical and physical

requirements for all types of cables (UTP, STP, co-axial and optical fiber

cables). EIA/TIA-568 standard also specifies the color coding, cable diameter

and other electrical characteristics, such as cross-talk, attenuation etc for

cables. The first EIA/TIA-568 specifications were released in 1991and revised

time to time with being added to new defined categories.

To limit the signal degradation caused by EMI and RFI effects, UTP cable

designers rely solely on the cancellation effect produced by the twisted wire

pairs. The number of twists in the wire pairs also varies for further reduction of

cross talk between the pairs in UTP cable. UTP cable must follow precise

specifications about the number of twists permitted per meter of cable.

UTP cable contains 8 wires, each 2 wires twisted together into 4 pairs with a

plastic jacket. The two wires of each twisted pair represent the negative and

positive paths of a complete circuit. Each wire consists of stranded copper with

own plastic color coded cover. The two wires of each twisted pair are called the

tip wire and the ring wire. Depending on the number of twisted pairs and the

application, each pair of UTP cable performs different function. Irrespective of

the type of function, the cables carry only electrical signals between networking

devices allowing communication.

Introduction


1.3.3 Self noise reduction technique of UTP cable

In a twisted –pair cable, the two conductor wires are twisted around each

other. The transmitted signal is the difference voltage between the two

conductor wires [12]. The directions of current flow in each wire of a pair are

opposite to each other as shown in the fig 1.16 (a).

Fig 1.16 (a): Current flow in a twisted-pair cable

Since the two currents in a twisted pair are equal and opposite, the two

magnetic fields produced by the two currents cancel each other. They cancel

out any magnetic interference caused by outside noise sources. The twisted-

pair cable is therefore less prone to interference exhibiting a self –shielding

property fig 1.16 (b).

Fig 1.16 (b): Shielding of twisted pair cables

Introduction


Twisting of the wires in a pair reduces crosstalk between pairs to minimum.

Twisting helps to reduce EMI and RFI. It also helps in balancing the mutual

capacitance of the cable pair. The twist rate (also called pitch of the twist,

usually defined in twists per meter) makes up part of the specification for a

given type of cable.

1.3.4 Requirements of UTP

The following are the main requirements of UTP cable [5]:

• UTP has four individually twisted pairs per cable.

• The characteristic impedance of each pair is 100 Ohms +/- 15%.

• Copper conductors of 24 Gauge (0.5106-mm-diameter) or optionally 22

Gauge (0.6438 mm diameter) are used.

UTP cables are used for Ethernet, Token Ring, CDDI, ATM, ISDN, analog

telephone and other types of communication. UTP cable is frequently referred

to as ‘Ethernet Cable’ also. Performance of UTP cables are guaranteed up to

100 meters between devices. Technically, the distance limitation is 90 meters

for structured cabling and a total of 10 meters for patch cords on either end.

1.3.5 Most popularly used cables

Different most popularly used UTP cables [13-17] are described below in

brief:

• CAT5: CAT5 is a cable standard supporting Fast Ethernet speed. Its

cable types, connector types and cabling topologies are defined

Introduction


byTIA/EIA-568-B. CAT5 is most commonly used for 100 Base-TX and

1000 Base-T.

CAT5 usually comprises of 4 pairs of copper conductors, but Fast Ethernet

utilizes only 2 pairs. Cable runs are limited to a maximum recommended length

of 100m (328 feet).

• CAT5e: CAT5e is an Enhanced version of CAT5. It supports Gigabit

Ethernet (speed up to 1000Mbps) operation over short distances. It

utilizes all the 4 twisted pairs of the cable and it is backward compatible

with ordinary CAT5. Both CAT5 and CAT5e have the same bandwidth

specifications, 100MHz. The difference between CAT5 and CAT5e are in

their transmission performance. CAT5e is with additional electrical

characteristics such as power sum NEXT, equal level far-end cross –talk,

power sum equal level far-end cross-talk and return loss.

• CAT6: Cat6 is a cable standard for Gigabit Ethernet and other network

protocols that are backward compatible with CAT5 and CAT5e. CAT6

specifications are more stringent for cross-talk and noise than CAT5/5e.

CAT6 provides a performance up to 250MHz. It is an excellent choice for

10Base-T,100Base-Tx(Fast Ethernet),1000 Base-T/1000 Base-

TX(Gigabit Ethernet) and 10GBase-T(10Gigabit Ethernet).CAT6 cable

contains 4 twisted pairs, made of 22 to 24 AWG copper conductors to

meet ANSI/TIA-568-B.2-1 performance specifications. CAT6 patch

cables are normally terminated in 8P8C modular connectors (often

referred as RJ-45). For CAT6 cable and connectors, the characteristics

Introduction


Attenuation, NEXT and PSNEXT are significantly lower than CAT5 and

CAT5e.

• CAT6a: CAT6a cable or Augmented Category 6 provides a

performance up to 500MHz, which is twice that of CAT6. CAT6a

standard was defined in 2008 in ANSI/TIA/EIA-568-B-2-10 for enhanced

performance standards for twisted pair cable. When compared with

CAT6, CAT6a performs at improved specifications, especially for alien

cross-talk. CAT6 exhibits high alien noise at high frequencies. Table 1.9

shows UTP cable specifications.

Table 1.9: UTP cable specifications

CAT5 CAT5e CAT6

Ratified 1991 1999 2002

Frequency 100MHz 100MHz 250MHz

Attenuation 22dB 22dB 19.8dB

Characteristic

impedance

100Ω±15% 100Ω±15% 100Ω±15%

NEXT 32.3dB 35.3dB 44.3dB

PS-NEXT - 32.3dB 42.3dB

FLEXT - 23.8dB 27.8dB

PS-ELFEXT - 20.8dB 24.8dB

Return Loss - 20.1dB 20.1dB

Delay skew - 45ns 45ns

Introduction


1.3.6 Technical Specification of UTP cables

• CAT5e: Technical specifications of CAT5e cable [18] are given below:

Cable Construction

Cable Properties

Conductor Bare Cu Wire

Insulated Material PE

Number of twisted pair 4

Sheath Material PVC or OHLS

Outside diameter of conductor 0.50mm

Outside diameter of insulation 0.90mm

Outside diameter of sheath 4.75mm

Min installation bend Radius 8×Dia

Min installed bending radius 4×Dia

Max installation Tension 100N

Max Installed Tension Zero

Installation Temp range 0 to 500C

Operating Temp Range -200 to 600

Introduction


Electrical Characteristics @ 200C

Characteristic impedance (1-10 & 20-

100MHz)

100±15Ω

Characteristic impedance (10-20MHz) 100±12Ω

DC Conductor Loop Resistance 19Ω/100m

Max Resistance unbalance ≤ 2%

Nominal velocity of propagation 66%

Nominal Capacitance 50pF/m

Max Capacitance unbalance 1600pF/Km

Insulation Resistance (500V) ≥2000MΩ,Km

• CAT6: Technical specifications of CAT5e cable [19] are given below:

Cable Construction

Conductor Bare Cu Wire

Insulator Material PE

Number of twisted pair 4

Spline Material PVC or LSOH

Sheath Material PVC or LSOH

Outside Diameter of Conductor(AWG) 0.59mm(23)

Outside Diameter of Insulation 1.045mM

Outside Diameter of Sheath PVC (OHLS) 5.8(5.3)mm

Introduction


Cable Properties

Electrical Characteristics @ 200C

Min. Installation Bend Radius 8×Dia

Min. Installed Bending Radius 4×Dia

Max. Installation Tension 100N

Max. Installed Tension Zero

Installation Temp. Range (Installed) 0 to 500C

Operating Temp. Range -200 to 600C

Characteristic impedance (1-100MHz) 100±15Ω

Characteristic impedance (100-

250MHz)

100±18Ω

DC Conductor Loop Resistance 15Ω/100m

Max Resistance unbalance ≤ 2%

Nominal Velocity of Propagation 66%

Nominal Capacitance 50pF/m

Max Capacitance unbalance 1600pF/Km

Insulation Resistance (500V) ≥2000MΩ,km

Introduction


1.3.7 Some guidelines for cabling installation

Recommended Cabling Practices

The followings are some recommended Cabling Practices [4]:

1. The connecting hardware should be compatible with the installed cable.

Any connecting hardware that is of a lower category than the cable being

used, should not be used.

2. Each horizontal cable should be terminated on a dedicated network

output. No cable should be leaved without termination.

3. The main cross-connect should be located near the centre of the

building. Cross-connect should not be located where the cable distance

will exceed the maximum allowed distance.

4. The twist of horizontal and backbone cable pairs should be maintained

up to the point of terminations.

5. The minimum bending radius of horizontal cables should be 4 times the

cable diameter. Making of sharp bends with cables are not

recommended.

6. Cabling should be placed at a sufficient distance from a source of EMI.

Electric wires (power line), fluorescent light are the examples of sources

of EMI.

When running cable, a few rules of thumb are advised to follow:

1. Use of more cable than need.

2. Testing of every part of an installed network.

Introduction


3. Keeping a distance of at least 3 feet away from fluorescent light boxes

and other sources of EMI.

4. When the cable is run across the floor, the cable should be covered with

cable protectors.

5. Cable ties (not tape) should be used to keep cables in the same location

together.

6. There should be room within the conduit or casing for future expansion

of cabling.

Minimum bending radius for cables

According to EIA/TIA SP-280A the minimum bending radius for UTP is 4

times the cable outside diameter [4]. For multi-pair cable, the minimum bending

radius is 10 times the cable outside diameter.

For fiber optic cables not in tension, the minimum bend radius is 10 times of

diameter. Fiber optic cables loaded in tension may not be bent at less than 20

times of diameter. According to SP-2840A no fiber optic will be bent on a radius

less than 3cm.

Minimum for pulling during installation is 8 times the cable diameter,

minimum installed radius is 6 times the cable diameter for riser cable, 4 times

the cable diameter for horizontal cable.

UTP cabling installation practices

Followings are some common UTP cabling installation practices [4]:

Introduction


• To avoid stretching, pulling tension should not exceed 110N or (25 lb f)

for 4-pair cables.

• Installed bend radii shall not exceed 4 times the cable diameter for

horizontal UTP cables and 10 times the cable diameter for multi-pair

backbone UTP cables.

• Avoid cable stress, as caused by cable twist during pulling or installation

– tension in suspended cable runs – tightly clinched cable ties or staples

– tight bend radii.

• Horizontal cables should be used with connecting hardware and patch

cords (or jumpers) of the same performance category or higher.

References

[1] Vikas Gupta, ‘Hardware and Networking’, Dreamtech Press, 2009.

[2] D.P. Nagpal, ‘Data Communication and Networking’, S. Chand, 2011.

[3] Behrouz A Forouzan, ‘Data Communications and Networking’, Tata

McGraw-Hill, 2008.

[4] ‘Introduction to Structured Cabling’, Division of Information Technology, Sept

2000.

[5] ‘Unshielded Twisted Pair (UTP) Cabling’. Sydnet, Firefox Document.

[6] ‘Twisted Pair Cable’, www.epanorama.net/documents/wiring/twisted

pair.html.

[7] ‘Extron Electronics-UTP Technology’, www.extron.com.

Introduction


[8] ‘Principles of Unshielded Vs. Shielded Network Cabling’ www.mohawk-

cable.com.

[9] Betsy Ziobron, ‘Twisted pair connectors continue technological evaluations’

HYPERLINE.

[10] Clyde F. Coombs. Jr.,Catherine Ann Coombs, ‘Communication Network

Test and Measurement Handbook’, Mc Graw- Hill, 1998.

[11] Subir Kumar Sarkar, ‘Optical Fibres and Fibre Optic Communication

Systems’, S. Chand & Company LTD. , 2ND edition 2001.

[12] Bdwin Wright, Deon Reynders, ‘Practical Telecommunications and

Wireless Communications for Business and Industry’, IDC Technology, 2004.

[13] ‘Cable Characteristics’, http://www.iphelp.ru/faq/36/cho7levl1sec4.html

[14] ‘Cabling’, MHTML Document.

[15] ‘Understanding CAT-5 Cables’, [email protected]

[16] ‘Cat5e UTP 4 Pair PVC Cable’, Technical Information, ultima-

comms.com

[17] ‘Category 5e UTP Cable, 25 pair’, www.ampnet connect.com

[18] ‘UTP Data Cable,Cat5e’, Datasheet, Hellerman Tyton Data Ltd., Cornwell

Business Park. www.htdata.co.uk.

[19] ‘UTP Data Cable,Cat6’, Datasheet, Hellerman Tyton Data Ltd., Cornwell

Business Park. www.htdata.co.uk.

Documents

Chapter 1 : Introduction - Shodhgangashodhganga.inflibnet.ac.in/bitstream/10603/50835/10... · Currently, Unshielded Twisted Pair (UTP) cable is the most popularly used copper-based