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Transmissionistheprocessoftransportinginformationbetweenend ointsofas stemornetwork.
Transmissionsystems
may
use
copper
cable,
optical
cable,
or
radiochannelstointerconnectfarendandnearend.
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TransmissionMedia
Guided
Cable
Medium
more
important
than
the
signal Ungui e
Atmosphere
OuterSpace
Signalmoreimportantthanthemedium
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Twoinsulatedcopperwiresinaspiral
Twistingdecreases
crosstalk
Mostcommonformforanalo anddi ital
Usedintelephonesystem
Subscriberloops
Fromapersonshometothelocalofficeofthephone
company
10Mbpswithnewerat100Mbps
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LongDistance 4 Mb s
ISDN Integrated
Services
Digital
Network
Digital Repeatersrequiredevery23kilometers
Analog Bandwidthof250KHz,carryafewvoicechannels
Susceptibletonoise,shielded (STP)andunshielded
. Comparedtoopticalandcoaxtwistedpairislimited
inbandwidth distance anddatarate
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ara e nes are o en use as
part of antenna arrays. Ordinary
television twinlead, is an example
Figure (a).
Parallel lines can be shielded to
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,
illustrated
in Figure (b).
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Hollowoutercylindricalconductor
surroundingasingle
view
Mostversatileofmediums usedforTV lon
distancetelephone,andLANS
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Partoflongdistancetelephonenetwork
,
Transmitsboth
analog
and
digital
signals
Fre uenc characteristicssu eriortotwisted air
Lesssusceptibletonoise
Forlong
distance
Amplifiersneededeveryfewkilometers
Repeatersneededeverykilometerorso
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Coaxial Cable Applications
For coaxial cable, the characteristic
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,
glassor
plastic
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Betterthancoaxialcableortwistedpair
Dataratesof2Gb sover10sofKm
Lightweight
good
for
buildings
Lowerattenuationthancoaxortwisted
o e ec e yex remee ec romagne c e s
Crosstalkandimpulse
Verydifficult
to
tap
good
security
Applications
LongHaultrunks,metrotrunks,ruralexchangetrunks,more
loopsand
in
LANS
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Operatesinrange1014 to1015 Hz
Multimode Varietyofanglesoflightwillreflectandpropagate
SingleMode
Radiusofthecore=orderofawavelength
Superiorperformance
Twodifferentlightsources bothemitlightwhenvoltageapplied
LED Light
Emitting
Diode
less
costly,
longer
life
ILDInjectionLaserDiode greaterdatarate
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Antennae
FocusedEM
beam
Thehigherfrequencythemorefocused
Omnidirectional
Lowerfrequency
Threerangesoffrequencies
26GHz 40GHzmicrowave
30MHz
1GHz
broadcast
radio
3x10**11to2x10**14Hzinfrared
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TerrestrialMicrowave
ara o c
s
Narrowbeam lineofsightontowerstoavoidobstacles
Seriesoftowersforlongdistance
Applications:
VoiceandTV
Shortpoint
to
point
between
buildings
MainSourceofloss
Attentuation especiallywithrainful
Re eaters or am lifiers 10 to 100km
Interferencewith
overlapping
bands
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SatelliteMicrowave
Itisessentiallyamicrowaverelaystation
Receivestransmission
on
one
frequency
Transmitsonasecondfrequency
Operateson
anumber
of
frequency
PointtoPoint
Groundstationtosatelliteto
Multipoint
Groundstationtosatellitetomu p erece v ngs a ons
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SatelliteMicrowave Satelliteorbit
35,784Km,tomatchearthrotation
ays xe a ove e
transmitter/receiverstation
as
earthrotates
Satellitesneedtobeseparatedby
distance
Avoidinterference
Applications
, ,Optimum frequency range 1 10 GHz
Below 1GHz results in noise, above 10GHz results in severe
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a enua on
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Omnidirectionalunlikesatellite
Frequencyrange
Radio3kHzto300Ghz
Broadcastradio 30MHzto1GHz
Broadcastradio
Transmissionlimitedtolineofsight
Lesssensitivetoattenuationfromrainfallthanmicrowave
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eachother
or
via
reflection
No
frequency
allocation
or
licensing
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