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8/3/2019 Notes 1 BIT3
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TEL-380
. a zaDepartment of Electrical Engineering
Universit of Malawi - Pol technictchadza@poly.ac.mw
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Goal
To introduce the properties of various
network systems.
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Ob ectives
understand the major properties of various
make informed choice of an appropriate
application
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Outline Data Communications
Carriers T1 And T-Carrier S stem
Analog Vs. Digital Transmission
Baseband Vs. Broadband
Telephony Integration
.
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Outline Packet Switchin Technolo ies
Fiber Distributed Data Interface
ISDN ATM
Voice Characteristics Voice Processing
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transmitter to a receiver.
n orma on rans er s roug s a
smallest unit of information that can beprocesse or ranspor e over a c rcu .A byte is a set of eight bits equivalent to
an oc e or c arac er.
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,concepts or instructions in a formalized
,
interpretation or processing by human.
Information is a message received and
un ers oo
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Communication System Model
e un amen a purpose o a acommunication is exchanging informationetween two agents.
A simple communication system modelconsists of a source, transmitter,transmission system, receiver and
destination.
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Source device that generates data to be
transmitted e.g. telephone,computer.
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Transmitter device that encodes data to be
ransm e n suc a way as o crea eelectromagnetic signals matching
e.g. modem
Transmission S stem physical medium that carries signals
produced by the transmitter. It can be a
s ng e w re connec ng wo e ep ones ora vast network connecting thousands of
. . . , .
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ece ver device that accepts a signal from the
a usable form for the destination devicee. . modem.Destination
acce ts a si nal from the receiver e. .telephone, computer or network switch.
It usually processes data in some way so
a s usa e y a uman user or aprogram running on the device.
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ata ransm ss on There are basically two data formats:
.
All bits in a single character are.
It is applied for connections within acom uter.
It has shorter distance limitations.
Printer connections t icall use aralleldata transmission to send data at once.
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Consider for instance a byte 10101110
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each bit has its own transmission line and.
implementation to accomplish this is
transmission line.
bits of data are transmitted bit by bit overa sin le channel.
normally used for long distances and isslower than parallel.
implementation is quite simple.
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It is used between two computers, from,
Networks (LANs) and Wide AreaNetworks WANs .
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Forms Of Serial Transmission
a. Asynchronous
ready and start and stop signals are
placed either side of each character.
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simple and cheap technique.
ync ron sat on s esta s e or eacand every byte.
bits per character.
a block is large hence not efficient forlarge blocks.
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ync ronous Data is collected in a storage area called
u er an s sen n oc s w a s arand stop bits at each end of the block.
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