Viva Voce questions on communication systems

Question-1:: What do you understand by Communication. Question-1 Answer: Communication is the process by which data is either transferred or received from one place to another via communication channel. Question-2: Draw the Basic Block Diagram o Communication !ystem. Answer: The Answer:  The block diagram of communication system is given as follow:

Basic Block Diagram of Communication System

Block Diagram of Communication system consists of f ollowing part: At transmitter "nd 1# Source 2# Source 2#  Source Coder $# Channel Coder %# Modulator &# Communication Channel At 'ecei(er "nd )# Demodulator *# Channel Decoder +# Source Decoder ,# Destination ,#  Destination Question $: "lain dierent modes used or communication. Answer: ccording to the mode of communication! it is divided into 1# /ine Communicatio Communication: n: "n  "n this mode of communication! the medium of transmission is a pair of conductors called called transmission lines. lines. Both the T# and $# are connected connected via a wire or line. 2# Wireless or 'adio 'adi o Communication Communi cation:: "n this mode! a message is transmitted through a open medium as in space by electromagnetic wave which are known as radio waves. Question %: What are dierent tyes o communication system. Answer: Their are three basic types of communication system! which are% 1# !imle Communication !ystem:

Simple# Communication System

&ere! the communication system that is capable of transmitting information through! called simple# transmission system. "n simple# type! one unit is e'uipped with a transmitter and the other side is e'uipped with only one receiver but communication is done only one way by transmitter. 0or "amle: T.(. broadcast system. 2# al-Dule Communication !ystem:

&alf%Duple# Communication System

&ere! the communication system that is capable of transmitting information in both directions but the flow is only one way at a given time that why it is known as half%duple#. "n &D) type! one unit is e'uipped with transmitter as well receiver at one end and a transmitter%receiver at the other end but information can*t flow simultaneously in both the directions. 0or "amle: +alkie%Talkie,  $# 0ull Dule Communication !ystem:

-ull Duple# Communication System

&ere the flow of communication takes place in both the direction simultaneously. -ull%duple# thernet connections work on the principles of full%duple# where data packets are received and sent simultaneously

at

a

given

time.

0or "amle: /hone Question

&: What

is

modulation

and

gi(e

methods

used

or

modulation.

Answer: Modulation is the process by which some characteristics of signal known as 0Carrier Signal,  is varied in accordance to the instantaneous value of the another signal known as 0Message Signal,. ethods

o

odulations

are:

12 ngle

Modulation

32 mplitude Modulation Question

): "lain

why

modulation

is

re3uired4

Answer: 1. +hen we want to transmit electrical signal over an antenna! through free space! it must be converted into electro%magnetic waves. 4nly electro%magnetic waves have the property to travel through space 5vacuum2 at the speed of light message signal or voice signals have low fre'uencies. 2. Signal $. To

with make

low msg

fre'uencies signal

or

cannot voice

travel

signal

longer

travel

distance.

longer

distance.

%. To increase the signal to noise ratio. Question *: What is the dierence between analog modulation and digital modulation. Answer: "n analog modulation bandwidth re'uired is low while in digital modulation due to higher bit rate! heigher channel bandwidth are re'uired. Question

+:

What

is

multileing.

"lain

its

tyes.

Answer: Multiplexing is defined as the process in which a number of message signals are combined together to form composite signals so that they can be transmitted through the common channel. 5yes

o

12 -re'uency

multileing:

Division

Multiple#ing

32 Time Division Multiple#ing Question

,:

6i(e

the

limitation

o

7//

!ynthesi8er.

Answer: "t suffers from tolerance which occurred in its analog components. &ere! short term drifts are caused due to variation in the filter and (C4 components. Question

19:

Answer: Companding C7A;D<;6=

"lain is

the

term

the derived

C7'"!!<;

from

term the

combination >

comanding. of

two

terms

"?7A;D<;6

"n the process of Companding! the weak signals are amplified and strong signals are attenuated before applying them to a uniform 'uanti6er.