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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.