8/21/2019 Viva Voce questions on communication systems

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Question-1: What do you understand by Communication.

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 block diagram of communication system is given as follow:

Basic Block Diagram of Communication System

Block Diagram of Communication system consists of following part:

At transmitter "nd

1# Source

2# Source Coder

$# Channel Coder

%# Modulator

Communication Channel

At 'ecei(er "nd

)# Demodulator

*# Channel Decoder

+# Source Decoder

,# Destination

Question $: "lain dierent modes used or communication.

Answer: ccording to the mode of communication! it is divided into

1# /ine Communication: "n this mode of communication! the medium of transmission is a pair of

conductors called transmission lines. Both the T# and $# are connected via a wire or line.

2# Wireless or 'adio Communication: "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 dierent tyes o communication system.

Answer: Their are three basic types of communication system! which are%

1# !imle Communication !ystem:

http://blog.oureducation.in/wireless-communication-concepts/http://blog.oureducation.in/wireless-communication-concepts/

8/21/2019 Viva Voce questions on communication systems

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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 "amle: T.(. broadcast system.

2# al-Dule 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 "amle: +alkie%Talkie, 

$# 0ull Dule 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 "amle: /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:

http://blog.oureducation.in/digital-modulation/http://blog.oureducation.in/digital-modulation/

8/21/2019 Viva Voce questions on communication systems

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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 with low fre'uencies cannot travel longer distance.

$. To make msg signal or voice signal travel longer distance.

%. To increase the signal to noise ratio.

Question *: What is the dierence 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 multileing. "lain its tyes.

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.

5yes o multileing:

12 -re'uency 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: "lain the term comanding.

Answer: Companding is the term derived from the combination of two terms

C7A;D