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INFORMATION TECHNOLOGY

PRESENTATION ON

VARIOUSMEDIUM

FORCOMMUNICATION


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MEDIUM OF C OMMUNICATIONS

What are computer communications ?Process in which two or more computers or devices transfer data,instructions, and information


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Sendingdevice initiates

instruction totransmit data,instructions, or

information

C OMMUNICATIONS

What is needed for successful communications?

Communicationsdevice connects

the communicationschannel to the

receiving device

Receivingdevice accepts

transmission of data,instructions, or

information

Communicationsdevice connects

the sending device tothe communications

channel

Communicationschannel media

on which data,instructions, or

information travel


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T ELECOMMUNICATIONS S YSTEMC OMPONENTS

C omputer to process information.

T erminals or input/output devices (source/destination)

C ommunication channels => C ommunication channelsuse various communication media, such as telephonelines, fiber optic cables, coaxial cables, and wirelesstransmission.

C ommunication processors => modems, controllers, andfront-end processors.


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P HYSICAL T RANSMISSION M EDIA

What are twisted-pair cable and coaxial cable ?

Twisted-pair cable is used for telephone systems and network cabling

Coaxial cable is often used for cable television wiring


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C OAXIAL C ABLE

In its simplest form, coaxial consists of a core made of solidcopper surrounded by insulation, a braided metal shielding,and an outer cover.


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C OAXIAL C ABLE

It minimizes both effect:skin effectradiation effect


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C OAXIAL C ABLEA transmission medium consisting of thicklyinsulated copper wire, which can transmit alarge volume of data than twisted wire.

Advantages : I t is often used in place of twisted wire for important links in a networkbecause it is a faster, more interference-freetransmission medium (speed : 200 megabits persecond).

Disadvantages : C oaxial cable is thick, is hardto wire in many buildings. I t does not supportanalog conversations.


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G LASS F IBERS

O ptical fibers uses light to transport data A dvantages

y U se of light eliminates interferencey C arries of pulse of light much farthery C arries more information than wiresy R equires only a single fiber

D isadvantagesy I nstallation requires special equipmenty D ifficult to locate a break in fibery D ifficult to repair a broken fiber


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P HYSICAL T RANSMISSION M EDIA

What is fiber-optic cable ?

C apable of carryingsignificantly more

data at faster speedsthan wire cablesLess susceptibleto interference(noise) and, therefore,more secureSmaller size (thinner and lighter )


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OPTICAL F IBER

Plastic coating

Single core

Opticalcore

Opticalcladding

Multicore


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W IRELESS T RANSMISSION M EDIA

What is a communications satellite ?

Space stationthat receivesmicrowave signalsfrom earth-basedstation, amplifiessignals, and

broadcasts signalsback to anynumber of earth-based stations


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CLASSIFICATIONS OF W IRELESS TRANSMISSION

Classification by Method

Infrared

Laser

Narrow-band radio

Spread-spectrum radio

Microwaves


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Microwave: technology has applications in all three of the wireless networkingscenarios: LAN, extended LAN, and mobile networking. Microwavecommunication can take two forms: terrestrial (ground) links and satellite links.The frequencies and technologies employed by these two forms are similar, but asyoull see, distinct differences exist between them.

Infrared: technology allows computing devices to communicate via short-range wireless signals using infrared lights wherein they are typically are limitedto within 100 feet. Infrared devices are insensitive to radio-frequencyinterference, but reception can be degraded by bright light.


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R ADIO

U ses electromagneticradiation to transmit dataO

perates at radio frequencyT ransmissions referred to asRF transmissionsD oes not require a direct

physical connection betweencomputers

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