CONTENTS
Page No.
Chapter 1 : AMPLITUDE MODULATION
1
1.1
Introduction
1
1.2
Development in Communication System
1
1.3
Modulation
4
1.4
Need for Modulation
4
1.5
Principles of Amplitude Modulation
6
1.5.1 Derivation of AM Signal
6
1.5.2 AM Envelope
8
1.5.3 AM Frequency Spectrum and Bandwidth
8
1.5.4 Coefficient of Modulation & Percent Modulation
9
1.5.5 Condition for Over, Under and Critical Modulation
11
1.5.6 AM Power Distribution
12
1.5.7 AM Current Calculation
14
AM Modulating Circuits
15
1.6.1 Low Level AM Modulator
16
1.6.2 Medium Power AM Modulator
17
AM Transmitter
20
1.7.1 Low Level Transmitter
20
1.7.2 High Level Transmitter
21
1.8
AM Receiver
22
1.9
Receiver Parameters
23
1.6
1.7
1.10 Types of AM Receivers
25
1.10.1 Tuned Radio Frequency Receiver (TRF)
26
1.10.2 Superheterodyne Receiver
27
1.10.3 Double Conversion AM Receiver
30
Solved problems
31
Exercises
Questions
35
36
Chapter 2 : ANGLE MODULATION
39
2.1
Introduction
39
2.2
Angle Modulations
39
2.3
Difference between Frequency and Phase Modulation
39
2.4
Mathematical Analysis
41
2.5
FM and PM Waveforms
44
2.6
Phase Deviation and Modulation Index
45
2.6.1 Frequency Deviation
46
2.6.2 Phase and Frequency Modulators and Demodulators
47
2.7
Frequency Analysis of Angle Modulated Wave
47
2.8
Bandwidth Requirement of Angle Modulated Waves
49
2.9
Commercial Braodcast Band FM
51
2.10 Average Power of an Angle Modulated Wave
51
2.11 Frequency and Phase Modulators
52
2.12 Direct FM Modulators
53
2.13 Direct PM Modulators
57
2.14 Direct FM Transmitters
59
2.15 Indirect FM Transmitters
62
2.16 Pre-emphasis and De-emphasis
64
2.17 Angle Modulation Versus Amplidute Modulation
66
2.18 FM Receivers
67
2.19 FM Demodulator
68
2.20 FM Noise Suppression
75
2.21 Frequency Versus Phase Modulation
79
Solved problems
79
Exercises
80
Questions
81
Chapter 3 : PULSE MODULATION
83
3.1
Introduction
83
3.2
Types of Pulse Modulation
83
3.3
Pulse Code Modulation
85
3.4
Sampling Rate
93
3.5
Quantization Noise and Signal to Noise Ratio
94
3.6
Signal to Quantization Noise Ratio
95
3.7
Companding
96
3.8
Analog to Digital Signal
98
3.9
Delta Modulation
98
3.9.1 Introduction
98
3.9.2 Block Diagram of Delta Modulation
98
3.9.3 Type of Noise
100
3.10 Differential Pulse Code Modulation (DPCM)
101
3.11 Adaptive Delta Modulation
102
3.12 Inter symbol Interference (ISI)
106
3.13 Eye Pattern
108
Solved Problems
109
Exercises
110
Questions
110
Chapter 4 : DATA COMMUNICATION
111
4.1
Introduction
111
4.2
Brief History of Data Communication
112
4.3
The Evolution of Data Communication
112
4.4
Standards
114
4.5
Data Communications Circuits
115
4.6
Data Communication Codes
118
4.6.1 The Binary System
119
4.6.2 Baudot Code
119
4.6.3 EBCDIC
121
4.6.4 ASCII
121
4.7
4.8
4.6.4.1 ASCII Control Characters
122
4.6.4.2 ASCII Printable Characters
124
Error Detection and Correction
124
4.7.1 Even Parity
125
Error Control
126
4.8.1 Polling
126
4.8.2 Stop and Wait ARQ
128
4.8.3 Go-Back-N Error Recovery
4.8.4 Selective Repeat Error Recovery
4.9
130
132
4.8.4.1 Features required for Selective Repeat ARQ
132
4.8.4.2 Recovery of lost PDUs using Selective Repeat ARQ
133
4.8.5 Comparison of ARQ Methods
134
Hardware Serial Interface
134
4.9.1 Hardware Overview
136
4.9.2 Parallel Interface
139
4.9.3 Asynchronous versus Synchronous Transmission
141
4.10 Modem
143
4.10.1 Introduction
143
4.10.2 Origin of Modems
144
4.10.3 Speed of Modem
145
4.10.3.1 Why Difference in Speed with Cable Modem
4.10.4 Classification of Modems
146
147
4.10.4.1 Classifying Modems according to Range
148
4.10.4.2 Classifying Modems according to line type
149
4.10.4.3 Classifying Modems according to Operation Mode
149
4.10.4.4 Classifying Modems according to Synchronization
151
4.10.4.5 Classifying Modems according to Modulation
152
4.10.5 Data Rate
156
4.10.6 Choosing Your Internet Access Device and
Physical Connection
4.10.7 Classification of Modem with Speed
157
157
4.11 Modem Control
160
Questions
162
Chapter 5 : DIGITAL COMMUNICATION
163
5.1
Introduction
163
5.2
Sampling Theorem
163
5.3
Quadrature sampling of Band pass signals
169
5.4
Reconstruction of a message from its samples
170
5.5
Signal distortion in Sampling
172
5.5.1 Bound on Alaising Error
173
5.6
Signal to Distortion Ratio
175
5.7
Nyquist’s Criterion for Distortionless Baseband
Binary Transmission
185
5.8
Baseband M-ary PAM system
189
5.9
Digital Modulation Techniques
190
5.10 Binary PSK
192
5.11 Quarternary Phase shift keying
196
5.11.1 QPSK Transmitter
197
5.11.2 Bandwidth Considerations of QPSK
199
5.11.3 QPSK Receiver
200
5.12 Differential phase shift keying (DPSK)
201
5.12.1 DBPSK Transmitter
202
5.12.2 DBPSK Receiver
202
5.13 Frequency shift Keying
203
5.13.1 FSK Bit rate and Baud
204
5.13.2 FSK Transmitter
205
5.13.3 Bandwidth Considerations of FSK
206
5.13.4 FSK Receiver
207
5.14 PLL FSK Demodulator
208
5.15 Continuous Phase Frequency shift Keying (CP/FSK)(MSK)
208
5.16 Amplitude shift Keying
209
5.17 Probability of Error and Bit Error rate
211
5.18 Duo Binary signalling
215
5.19 Quadrature amplitude modulation
218
5.20 QAM Error performace
220
5.21 Intersymbol Interference
221
Solved Problems
223
Exercises
226
Questions
228
Chapter 6 : SPREAD SPECTRUM AND MULTIPLE
ACCESS TECHNIQUES
229
6.1
Introduction
229
6.2
Direct Sequence Spread Spectrum
237
6.3
Generating Pseudo Random Codes
239
6.4
Direct Sequence Spread Coherent Binary PSK
241
6.5
Signal space dimensionality and processing gain
244
6.6
Frequency Hopping Spread Spectrum (FHSS)
248
6.7
Access Schemes
252
6.8
Time Division Multiple Access (TDMA)
253
6.9
Frequency Division Multiple Access (FDMA)
258
6.10 Code Division Multiple Access (CDMA)
262
6.11 Wireless Communication Systems
264
6.12 Cellular Telephone Systems
266
Exercises
268
Questions
269
Chapter 7 : CODING TECHNIQUES
271
7.1
Introduction
271
7.1.1 Classification of Codes
271
7.2
What is coding
272
7.3
Coding Efficiency
273
7.4
Shannon Fano Coding
277
7.5
Huffman Coding
281
7.6
Error Control Coding (ECC)
285
7.7
Block Codes
286
7.8
Binary Code Space
287
7.9
Cycle Code
293
Exercises
296
Questions
298
TWO MARKS QUESTION & ANSWER
INDEX
299
317