Post on 11-May-2023
A TEXT BOOK OF
AANNAALLOOGG
CCOOMMMMUUNNIICCAATTIIOONN FOR
SEMESTER – II
SSEECCOONNDD YYEEAARR DDEEGGRREEEE CCOOUURRSSEE IINN EELLEECCTTRROONNIICCSS//
EELLEECCTTRROONNIICCSS AANNDD TTEELLEECCOOMMMMUUNNIICCAATTIIOONN EENNGGIINNEEEERRIINNGG
Strictly According to New Revised Credit System Syllabus
of Savitribai Phule Pune University (w.e.f June 2016)
Dr. G. R. PATIL M.E. (Electronics), Ph. D. (E&TC)
Professor & Head, E & TC Department,
Army Institute of Technology,
Dighi, PUNE
Price `̀̀̀ 325.00
N3574
ANALOG COMMUNICATION (SE E & TC) ISBN 978-93-83750-97-9
First Edition : January 2017
© : Author The text of this publication, or any part thereof, should not be reproduced or transmitted in any form or stored in any computer storage system or device for distribution including photocopy, recording, taping or information retrieval system or reproduced on any disc, tape, perforated media or other information storage device etc., without the written permission of Authors with whom the rights are reserved. Breach of this condition is liable for legal action. Every effort has been made to avoid errors or omissions in this publication. In spite of this, errors may have crept in. Any mistake, error or discrepancy so noted and shall be brought to our notice shall be taken care of in the next edition. It is notified that neither the publisher nor the authors or seller shall be responsible for any damage or loss of action to any one, of any kind, in any manner, therefrom.
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PREFACE
It gives me great pleasure in publishing this text book on "Analog Communication"
for the students of Second Year Degree Course in Electronics/Electronics and
telecommunication Engineering. This book is strictly written according to New Revised
Credit System Syllabus of Savitribai Phule Pune University (2015 Pattern).
As per the policy of the University, Engineering Syllabi is revised every five years. Last
revision was in the year 2012. New revision is coming little earlier, as university has
introduced Online System of Examination from year 2012.
As per the New Credit System, the Online Examinations Phase-I will be conducted
based on First & Second Units and Phase II on Third & Fourth Units. The Online
examinations will have objective types of questions with multiple choices. End Sem. Theory
Examination will be based on all the six units and that will be conducted in traditional way
and the Theory Course will have 4 credits.
This book provides an introduction to the theory on Analog Communication. The concepts
of Analog Communication are presented with Numbers of Examples, are also given to test
the understanding of the students.
Unit 1 provides the Concept of AM Transmission
Unit 2 provides the Concepts of AM Receiver
Unit 3 provides the Concepts of FM Transmission
Unit 4 provides the Concepts of FM Receiver
Unit 5 provides the Concepts of Noise
Unit 6 provides the Concepts of Pulse Analog Modulation.
Main feature of this book is, Complete Coverage of the New Credit System Syllabus
with large number of Worked (Solved) Examples and Exercises.
I have given Separate Book of Multiple Choice Questions (MCQ’s) which will be
very useful to the students especially for Online Examinations.
I take this opportunity to express our sincere thanks to Shri. Dineshbhai Furia, Shri.
Jignesh Furia, Mrs. Nirali Verma and Shri. M. P. Munde and entire team of Nirali Prakashan
namely Mrs. Deepali Lachake (Co-ordinator), who really have taken keen interest and
untiring efforts in publishing this text.
The advice and suggestions of our esteemed readers to improve the text are most
welcomed, and will be highly appreciated.
Pune Author
SYLLABUS
Unit I : AM Transmission (08 Hrs)
Base band & Carrier communication, Generation of AM (DSBFC) and its spectrum,
Power relations applied to sinusoidal signals, DSBSC – multiplier modulator, Nonlinear
generation, switching modulator, Ring modulator & its spectrum, Modulation Index.
SSBSC, ISB & VSB, their generation methods & Comparison, Block Diagram of AM
Transmitter and Broadcast technical standards.
Unit II : AM Reception (8 Hrs)
Block diagram of TRF AM Receivers, Super Heterodyne Receiver, Dual Conversion Super
heterodyne Receiver, Concept of Series & Parallel resonant circuits for Bandwidth &
Selectivity. Performance Characteristics: Sensitivity, Selectivity, Fidelity, Image Frequency
Rejection and IFRR. Tracking, Mixers. AM Detection: Rectifier detection, Envelope
detection; Demodulation of DSBSC: Synchronous detection; Demodulation of SSBSC:
Envelope detection
Unit III : FM Transmission (8 Hrs)
Instantaneous frequency, Concept of Angle modulation, frequency spectrum& Eigen
Values, Narrow band & wide band FM, Modulation index, Bandwidth, Phase Modulation,
Bessel’s Function and its mathematical analysis, Generation of FM (Direct & Indirect
Method), FM stereo Transmitter, Two way FM Radio Transmitter, Comparison of FM and
PM.
Unit IV : FM Reception (6 Hrs)
Block diagram of FM Receiver, FM Stereo Receiver , Two way FM Radio Receiver, FM
detection using Phase lock loop(PLL) ,Slope detector, Balanced Slope detector etc.
Unit V : Noise (6 Hrs)
Sources of Noise, Types of Noise, White Noise, Thermal noise, shot noise, partition
noise, Low frequency or flicker noise, burst noise, avalanche noise, Signal to Noise Ratio,
SNR of tandem connection, Noise Figure, Noise Temperature, Friss formula for Noise
Figure, Noise Bandwidth, Behavior of Baseband systems and Amplitude modulated
systems i.e.DSBSC and SSBSC in presence of noise.
Unit VI : Pulse Analog Modulation (6 Hrs)
Band limited & time limited signals, Narrowband signals and systems, Sampling
theorem in time domain, Nyquist criteria, Types of sampling- ideal, natural, flat top,
Aliasing & Aperture effect. PAM PWM & PPM. Introduction to Pulse Code Modulation.
CONTENTS
Unit I – AM Transmission
Chapter 1 : AM Transmission 1.1-1.112
1.1 Baseband and Carrier Communication 1.1
1.1.1 The Elements of a Communication System 1.2
1.1.2 Baseband Signal Transmission and Bandwidth Requirement 1.4
1.1.3 Communication Channel or Medium 1.6
1.1.4 Types of Transmission Mediums 1.7
1.1.5 Modulation Techniques 1.7
1.1.6 Necessity of Modulation (Need of Modulation) 1.8
1.1.7 Types of Modulation 1.11
1.1.8 Summary of Baseband and Carrier Communication 1.16
1.2 Amplitude Modulation (AM) DSB-FC 1.17
1.2.1 Frequency Domain Description of AM (Spectrum of AM) 1.20
1.2.2 Power Relation in AM Wave 1.24
1.2.3 AM for Multiple Sinusoidal Signals 1.27
1.2.4 Over Modulation 1.30
1.2.5 Measurement of Modulation Index 1.30
1.3 Generation of AM Signal 1.33
1.3.1 Practical AM Generation Techniques 1.35
1.3.2 High Level Amplitude Modulators 1.36
1.3.3 Low Level Amplitude Modulators 1.40
1.4 Double Sideband Suppressed Carrier (DSB – SC) Modulation 1.41
1.5 Generation of DSB-SC 1.49
1.6 Single Sideband Suppressed Carrier (SSB-SC) Modulation 1.53
1.6.1 Methods of Generation of SSB-SC Signal 1.57
1.6.2 The "Third Method" 1.59
1.6.3 Comparison between Filter / Phase Shift / Third Method 1.61
1.7 Independent Side Band (ISB) 1.62
1.8 Vestigial Sideband (VSB) Modulation 1.63
1.8.1 VSB Application in TV Broadcasting 1.65
1.9 Comparison Between AM, DSB, SSB, ISB and VSB 1.67
1.10 AM Transmitters 1.67
1.10.1 High Level AM Transmitter 1.68
1.10.2 Low Level AM Transmitter 1.69
1.10.3 Comparison of High Level and Low Level Modulation 1.70
1.10.4 Different AM Techniques (Forms of AM) 1.70
1.11 Broadcast Technical Standards 1.72
• Exercise 109
• University Problems 1.110
• University Questions 1.112
Unit II – AM Reception
Chapter 2 : AM Reception 2.1-2.52
2.1 Introduction 2.1
2.2 Tuned Radio Frequency Receiver 2.1
2.3 Block Diagram of AM Receiver (Superheterodyne Receiver) 2.2
2.4 Dual or Double Conversion Superheterodyne Radio Receiver 2.4
2.5 Concept of Series and Parallel Resonance Circuits 2.7
2.6 Performance Characteristics of Receiver 2.13
2.7 RF Amplifiers 2.22
2.8 Local Oscillator 2.23
2.9 Intermediate Frequency Selection 2.24
2.10 Mixer 2.25
2.11 AM Detection 2.29
2.12 Automatic Gain Control (AGC) 2.34
2.13 Demodulation of DSB-SC 2.37
2.14 Demodulation of SSB-SC Signal 2.40
• Exercise 2.48
• University Problems 2.50
• University Questions 2.51
Unit III – FM Transmission
Chapter 3 : FM Transmission 3.1-3.64
3.1 Introduction 3.1
3.2 Concept of Instantaneous Frequency 3.1
3.2.1 Phase Modulation and Instantaneous Frequency 3.3
3.2.2 Frequency Modulation and Instantaneous Frequency 3.3
3.2.3 Generalized Concept of Angle Modulated System 3.4
3.2.4 Modulation Indices 3.5
3.3 Frequency Spectrum and Bandwidth of Wideband Angle Modulated Wave 3.11
3.4 Narrowband FM and PM 3.19
3.4.1 Generation of Narrowband PM and FM signal 3.22
3.5 Generation of FM 3.23
3.5.1 Indirect Method or Armstrong Method 3.23
3.5.2 Direct Method of Generation of WBFM 3.25
3.5.3 WBFM using Varactor Diode 3.26
3.5.4 WBFM using Reactance Modulator 3.27
3.6 Comparison of FM and PM 3.29
3.7 FM Stereo Transmitter 3.29
3.8 Two Way FM Radio 3.32
3.9 Comparison Between AM and FM 3.35
3.10 Comparison Between WBFM and NBFM 3.37
• Exercise 3.60
• University Problems 3.60
• University Questions 3.63
Unit IV – FM Reception
Chapter 4 : FM Reception 4.1-4.20
4.1 Introduction 4.1
4.2 FM Receivers 4.3
4.3 Practical Frequency Demodulators 4.7
4.4 FM Stereo Receiver 4.17
4.5 Two Way FM Receiver 4.18
• Exercise 4.19
• University Questions 4.20
Unit V – Nosie
Chapter 5 : Noise 5.1-5.44
5.1 Introduction 5.1
5.1.1 Noise Sources / Types / Classification 5.1
5.2 Thermal Noise (Nyquist or Johnson’s Noise) 5.3
5.2.1 Thermal Noise Calculation for Resistors in Series 5.6
5.2.2 Thermal Noise Calculation for Resistors in Parallel 5.6
5.2.3 Thermal Noise for Reactive Circuits 5.7
5.2.4 Thermal Noise for Amplifiers in Cascade 5.8
5.3 Shot Noise 5.10
5.4 Partition Noise 5.12
5.5 Low Frequency or Flicker Noise 5.12
5.6 Burst Noise 5.13
5.7 Avalanche Noise (Due to Avalanche Breakdown) 5.14
5.8 White Noise 5.15
5.8.1 White Noise in Spatial Context 5.15
5.8.2 Statistical Properties 5.15
5.8.3 Additive White Gaussian Noise (AWGN) 5.17
5.8.4 Applications of White Noise 5.17
5.8.5 Power Spectral Density and Auto-Correlation Function of the
White Noise 5.18
5.9 Signal to Noise Ratio (SNR) 5.19
5.10 SNR of a Tandem Connection 5.20
5.11 Noise Factor and Noise Figure 5.21
5.11.1 Noise Figure Calculation for Receiver (Amplifier) System 5.22
5.11.2 Noise Figure from Equivalent Noise Resistance 5.24
5.11.3 Friss’s Formula 5.25
5.12 Noise Temperature 5.26
5.12.1 Equivalent Noise Temperature for Microwave Devices 5.26
5.13 Noise Figure, Noise Factor and Equivalent Noise Temperature
Conversion Table 5.28
5.14 Noise Equivalent Bandwidth 5.30
5.14.1 Technical Definition of Noise-Equivalent Bandwidth 5.31
5.14.2 Practical Design and Simulation for Noise Equivalent
Bandwidth of BPF 5.32
• Exercise 5.41
• University Problems 5.41
• University Questions 5.43
Chapter 6 : Behaviour of Analog Systems in Presence of Noise 6.1-6.28
6.1 Introduction 6.1
6.2 Noise in Baseband Communication Systems 6.2
6.3 Noise in Amplitude Modulated Systems 6.5
6.4 Pre-Emphasis and De-Emphasis in FM 6.16
• Exercise 6.26
• University Problems 6.27
• University Questions 6.28
Unit VI – Pulse Analog Modulation
Chapter 7 : Pulse Analog Modulation 7.1-7.52
7.1 Introduction 7.1
7.2 Band Limited and Time Limited Signals 7.1
7.3 Narrowband Signals and Systems 7.1
7.4 Sampling Theorem in Time Domain 7.2
7.4.1 Impulse or Ideal Sampling 7.2
7.4.2 Nyquist Criteria and Aliasing 7.7
7.5 Natural Sampling 7.14
7.6 Flat-Top Sampling 7.16
7.7 Comparison of Various Sampling Techniques 7.20
7.8 Introduction to Pulse Modulation 7.28
7.9 Pulse Amplitude Modulation (PAM) 7.29
7.10 Pulse Width Modulation (PWM) 7.33
7.11 Pulse Position Modulation (PPM) 7.38
7.12 Pulse Code Modulation (PCM) 7.44
7.12.1 Low Pass Filter 7.45
7.12.2 Sampling 7.45
7.12.3 Quantizing 7.45
7.12.4 Encoding 7.47
7.12.5 Regeneration 7.47
7.12.6 Decoding 7.48
7.12.7 Reconstruction Filters 7.48
7.12.8 Bandwidth Requirement of PCM 7.48
• Exercise 7.49
• University Problems 7.50
• University Questions 7.51
•••• Sample Question Paper for End. Sem. Theory Exam. P.1
���
Unit 1 | 1.1
UNIT - I
Chapter 1
AM TRANSMISSION
1.1 BASEBAND AND CARRIER COMMUNICATION
The Electronics field can be roughly categorized into three major areas :
1. Computers
2. Communication
3. Control
1440
1844-66
1876
1879
1887
1895
19010
1903-06
1923
1931
1940-45
1948
1954
1959
1962
2005
Invention of printing press
Telegraph communication
Telephone communication
Photographic film development
Discovery of Radio waves
Wiress Telegraphy
First Radio Transmission
Valve & Vaccum tube Invention
Television Invention
Discovery of Radio Astronomy
Radar Discovery & Implementation
Invention of transistor
Colour Television broadcast
Invention of integrated circuits
First satellite communications
All Advanced Communication Systems
Fig. 1.1 : Evolution of the Human Race's Communication Techniques
ANALOG COMMUNICATION (SE E&TC) AM TRANSMISSION
Unit 1 | 1.2
The computer field is the latest of the three, while communication field is the oldest one. The
field of communication is related with electronic equipments used for the transfer of
information like voice, video, digital data between two or more points.
Communication is the transfer of meaningful information from one location (the sender,
source, originator or transmitter) to other location (the destination or receiver). This
definition is a basic one that only requires that the term information be defined to complete
its meaning. Also, you can define the communication as the basic process of information
exchange between transmitter and receiver. Most communication in the past has been done
between one human and another. The communication systems in the past used two broad
techniques - visual and aural. The evolution of people's ability to use these techniques is
summarized in Fig. 1.1.
1.1.1 The Elements of a Communication System
The block diagram of the simplest possible electronic communication system is as shown in
Fig. 1.2.
Informationsource
Transmitter(TX)
Receiver(RX)
Communicationchannel or
medium
Noise /Interference
source
Destination
Fig. 1.2 : Block diagram of basic communication system
As seen from the Fig. 1.2, the basic components of a communication system are, transmitter,
a communication channel or medium and a receiver. Unwanted noise is inherently present in
the channel. The components of a communication system are as follows :
• Information
• Transmitter
• Medium or Communication Channel
• Unwanted Noise
• Receiver
Information or Input Signal :
The communication systems have been developed for communicating or transferring or
exchanging information from one location to other. The information can be as follows :
• human voice
• music
• picture or video signal
• data from computer
• or combinations of the above
ANALOG COMMUNICATION (SE E&TC) AM TRANSMISSION
Unit 1 | 1.3
Transmitter (Tx) :
Most of the times message coming from information source is not suitable for immediate
transmission. The task of transmitter block is to convert the electrical equivalent of the
information to a suitable form. Transmitter consists of electronic circuits such as amplifier,
oscillator and power amplifier for signal conditioning to cover the large range.
Communication Channel or Medium :
Depending on the type of communication medium, two types of communication systems will
be available, they are as follows :
Communication System
Wired Communication
or
Line Communication
Wireless Communication
or
Radio Communication
The wired communication medium can be conducting wires, cables and optical fibers. The
wireless communication medium can be free space.
1. Wired Communication : Wired communication systems use the communication
mediums like the simple wires, cables or optical fibers. The examples of wired
communication are telegraph system, telephone system, fax system, cable T.V. system,
Internet lines like leased lines, ISDN (Inter Services Digital Network) lines etc. This wired
medium cannot be used for the communication over long distances because of the
requirement of actual physical connection from one point of one location to other point
of other location.
2. Wireless Communication : Radio communication is the broad general term applied to
any form of wireless communication between two locations. Wireless communication
doesn't require any physical wire between transmitter (Tx) and receiver (Rx), instead the
signal is sent through air or free space via. transmitter antenna and received by receiver
antenna. Transmitter antenna radiates the signal in electromagnetic waveform and
received in the same form. For long distance communication like intercontinent
communication, Earth to Satellite, Earth to Moon, Earth to Planet etc., radio
communication is widely used.
Noise : Noise is random, unwanted electrical signal energy which gets added to the
transmitted signal via medium in electronic communication system. It is very much difficult to
separate the added noise from the transmitted signal. Also, receiver adds its own noise. So
overall signal quality degrades, hence degradeing the overall performance of communication
system. There are several ways of classifying noise. It may be subdivided according to type,
source, effect or relation to the receiver, depending on circumstances. It is most convenient
here to divide noise into two broad groups as follows :
ANALOG COMMUNICATION (SE E&TC) AM TRANSMISSION
Unit 1 | 1.4
Noise
External noise Internal noise
• Atmospheric noise
• Extraterrestrial noise
• Industrial noise
• Thermal agitation noise
• Shot noise
• Transit time noise
Atmospheric noise is caused by lightening discharges in thunderstorms and other natural
electrical disturbances occurring in the atmosphere. Extraterrestrial noise includes solar noise,
cosmic noise etc. Industrial noise is concerned with the sources such as automobile and
aircraft ignition, electric dc/ac motors and switching gear, high voltage transmission line
leakage etc. Thermal noise is due to thermal agitation in resistive component of system. Shot
noise is due to random variations in the arrival of electrons (or holes) at the output electrode
of amplifying device. Transit time noise is added due to the circuit operation above VHF
(Very High Frequency). Even though noise cannot be completely eliminated, its effect can be
minimized by using various noise reduction methods.
Receiver : The reception is exact opposite process of transmission. The received signal is
processed by the various circuits like pre-amplifier, mixer, oscillator, detector, demodulator,
driver amplifier and power amplifier.
Thus, we have studied the basic electronic communication system and its components.
Further the electronic communication systems can be categorized as Analog communication
systems and Digital communication systems. In Analog communication system, the
continuous varying signal such as sine wave is used. For example, audio and video signal
which is the output of microphone and video camera respectively. The data output from
computer is digital data representing the alphabets, characters, numerical etc. which is being
transmitted by digital communication system by either wired or wireless medium.
1.1.2 Baseband Signal Transmission and Bandwidth Requirement
Regardless of whether the original information signals are analog or digital, they are all
referred to as baseband signals. Following are the examples of the baseband signal
transmission given in Fig. 1.3 (a), (b), (c), (d).
Analog information
Baseband signal
(Parallel wire)
Telephone Telephone
(a) Voice as analog baseband signal
Analog Communication
Publisher : Nirali Prakashan ISBN : 9789383750979 Author : Dr. G. R. Patil
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