Media and their applications

Chapter 2

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Types of Network

Circuit Switched & Packet Switched

Signaling Techniques

Baseband & Broadband

Interference

Transmission Medium

Wired & wireless

Chapter Overview

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There are two kinds of networks over which data can be

transmitted.

Circuit switched network

Packet switched network

Types of Networks

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In a circuit switched network, there is a dedicated and a direct physical

connection between the sender and the receiver.

No other transmission can take place while the connection is active.

Once the current transmission is ended, other connections can be

made.

Ideal for voice communication as no interruption from other devices.

Circuit Switched Network

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This network requires data transmission be broken into

smaller units called packets.

Each packet is sent independently through the network.

It is used for data transmission because data is not as time-

sensitive as voice communication.

It allows multiple devices to share one line or frequency.

It facilitates error correction.

Packet Switched Network

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There are two ways to send a signal over a medium.

Baseband signaling

Broadband signaling

Signaling Techniques

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Sends one data signal across the network media.

Entire capacity of the media is used for the one data signal.

Signals are transmitted in a digital format.

Many devices can send and receive across the medium, but

only one at a time.

Used for computer network data transmissions.

Baseband Signaling

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Divides the cable into several different channels.

Signals are transmitted at different frequencies in an analog

mode.

Allows many different signals to be sent simultaneously on a

single cable.

Signal sent in only one direction.

Broadband Signaling

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The flow of a signal down the network media can become

distorted.

Common types of distortions are attenuation and

interference.

Factors Affecting the Transmission

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Attenuation is the loss of signal power.

Measured by the decrease in decibels (db) over a specific

distance.

Attenuation

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Interference is caused when a strong external signal

interferes with a signal. Radio frequency interference (RFI) is an interference caused by broadcast

signals from a radio or television transmitter.

Electromagnetic interference (EMI) when motor or source of intense electrical

activity creates an electromagnetic signal that interferes with a data signal.

Near end crosstalk (NEXT) and Far end crosstalk (FEXT) - interference from

another data signal being transmitted on adjacent wire.

Interference

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Media is the base for communication between devices.

Coaxial cables (coax).

Twisted Pair cable.

Fiber optic cables.

Wireless.

Transmission Media

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Coaxial cables are very common in connecting TV’s to cable

services or satellite.

It is used in these areas because of its high bandwidth and

shielding capabilities.

Coax cables are less prone to the external interferences, but

very costly to run.

Coaxial Cable (coax)

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Coaxial Cable (coax)

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Twisted-pair cables have replaced the coax cables in the

Ethernet networks.

Twisted-pair cables use the same technology used by the

phone company for the movement of electrical signals.

Twisted-pair cables come if two forms,

Unshielded Twisted-pair cables

Shielded Twisted-pair cables

Twisted-pair Cable

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Shielded twisted-pair Cable (STP) has a foil shield around the

pairs to provide extra shielding from electromagnetic

interference.

Unshielded twisted-pair Cable (UTP) has no such foil around

it. It uses the actual twists to eliminate interference.

STP provides better communication, but it is expensive

compared to UTP.

Twisted-pair Cable

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The standard method of connecting twisted-pair cables is via

a 8-pin connector called RJ-45 connector.

Twisted-pair cables are divided into three categories

depending upon their transmission speed.

Twisted-pair Cable

Designation Category Description

10BaseT Category 3 10 Mbps baseband Ethernet over twisted pair cable with a maximum length of 100 meters.

100BaseT Category 5 100 Mbps baseband Ethernet over twisted pair cable.

1000BaseT Category 6 1000 Mbps baseband Ethernet over four pairs of category 5 unshielded twisted pair cables.

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Twisted-pair Cable

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Fiber optic cable uses a beam of laser light to connect

devices over a thin glass wire.

The biggest advantage of fiber optic cables is the higher

bandwidth. These cables are used as a backbone to all the

large networks and internet.

The biggest disadvantage of fiber optic cables is the cost.

Fiber Optic Cables

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Making connection to a fiber optic cable is very difficult/

impossible.

It is very difficult to splice a fiber optic. Making the precise

connections on the end of fiber optic line is a highly skilled job

and is done by a specifically trained professionals.

Once the connector is fitted on the end, several forms of

connectors and blocks are used to make new connections.

Fiber Optic Cables

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Fiber Optic Cable

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Fiber Optic Cable

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Transmission is sent and received through invisible waves.

Unguided media is a phrase used to cover all transmission

media not guided by wire or fiber.

Unguided media includes radio frequency (RF), infrared (IR)

and microwave methods.

Unguided Media – Wireless

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Unguided media have one attribute in common, that they are

unguided and can travel to many machines simultaneously.

Allows the user to move freely around the office or campus

and still remain connected to the network.

Fastest-growing segment of network media today.

Less expensive than copper or fiber optic lines.

Unguided Media – Wireless

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Radio Frequency (RF) is the most common and widely used

method of wireless communication.

RF waves uses variety of frequency bands, each with special

characteristics.

Microwave is used to describe a specific portion of the RF

spectrum that is used for communication as well as other

tasks such as cooking.

RF/Microwave

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Advantages of Microwaves

Microwaves can penetrate through thick walls

Microwaves can propagate through rough terrain

Microwaves have broadcast capability

Microwaves provide cost-effective solutions

RF/Microwave

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IR is a band of electromagnetic energy just beyond the red

end of the visible spectrum.

IR is commonly used in remote control devices, wireless

devices like printers, keyboards, mice and PDA’s.

Drawbacks of IR

Slow

Cannot penetrate thick walls

Infrared (IR)

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The NIC serves as the connection between the personal

computer and the network media.

It connects to the computer on its base by plugging into an

expansion slot of the computer.

Another connection is accessible from the outside of the

computer and has connections for the cables to plug into

the network.

Network Interface Card

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Network Interface Card