it ppt varm
TRANSCRIPT
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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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CLASSIFICATIONS OF W IRELESS TRANSMISSION
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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CLASSIFICATIONS OF W IRELESS TRANSMISSION
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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