ELECTRONIC COMMUNICATIONS MODULATION AND TRANSMISION SECOND EDITION

CONTENIDOS

CAPÍTULO UNO
PRINCIPIOS DE MODULACIÓN DE AMPLITUD
1.1 Introducción ................................................... 1
1.2 Modulación ................................................... 1
1.2.1 Necesidad de Modular ............................. 2
1.2.2 Formas de Modulación ............................. 2
1.2.3 Conceptos Visuales ................................... 3
1.2.4 Frecuencias Laterales ................................ 4
1.2.5 Factor de Modulación y Porcentaje de Modulación ........ 6
1.2.6 La Matemática de la Onda AM ..................... 9
1.2.7 Resumen ................................................ 10
1.2.8 Relaciones de Voltaje de Modulación ............ 10
1.3 Relaciones de Potencia ................................ 12
1.4 Fasores Componentes de la Onda AM ............... 14
1.5 Espectro de Frecuencia Asignable .................. 15
1.6 Selección de Banda ....................................... 17
1.6.1 Banda Comercial de Radiodifusión AM ........... 17
1.6.2 Interferencia de Canal ................................ 17
1.6.3 Definiciones ............................................. 19
1.6.4 Potencia Radiada Efectiva ........................... 20
1.6.5 Código de Emisión .................................... 21

CAPÍTULO DOS
TRANSMISORES AM
2.1 Introducción ................................................. 27
2.2 Circuitos ....................................................... 27
2.2.1 Formación de la Señal Modulada ................. 28
2.2.2 Excitador .................................................. 29
2.2.3 Amplificador de Potencia ........................... 31
2.2.4 Amplificador de Conducción ....................... 31
2.2.5 Modulador ................................................ 32
2.2.6 Procesador de Audio ................................ 32
CONTENTS
xvii

4.2.1 RF Amplifier 105
4.2.2 The Mixer/Oscillator 106
4.2.3 Intermediate Frequency (IF) Amplifiers 107
4.2.4 Detector 107
4.2.5 Automatic Gain Control (AGC) 107
4.2.6 Output Reproducer 108
4.3 Double-Conversion Receivers 108
4.3.1 Image Frequency Rejection 109
4.3.2 Signal-to-Noise Ratio (S/N) 110
4.3.3 Sensitivity 111
4.3.4 Selectivity 111
4.3.5 Dynamic Range 112
4.4 Receiver Circuits: The Front End 113
4.4.1 The RF Amplifier 113
4.4.2 Mixer 115
4.4.3 The Local Oscillator 118
4.4.4 Tuning Capacitors 119
4.4.5 High- or Low-Frequency Oscillator? 122
4.4.6 Front-End Circuits 122
4.5 Intermediate-Frequency Amplifiers 125
4.6 AM Detectors 132
4.7 Automatic Gain Control (AGC) 136
4.8 Audio Amplifiers 137
4.9 Squelch 141
4.10 Receiver Schematics 142
4.11 Loudspeakers 146
4.12 Pilot Carrier Receivers 148
4.13 Independent Sideband Receivers 149
4.13.1 Frequency Synthesis 150
4.13.2 Product Detectors 152
4.14 AM Stereo 152
4.15 AM Receiver Testing 155
4.15.1 Test Setup 156
4.15.2 Alignment 158
4.15.3 Noise Measurements 159
4.15.4 Receiver Sensitivity Measurements 161
4.15.5 Selectivity Measurements 162
4.15.6 Dynamic Range Measurements 162

CHAPTER FIVE
FREQUENCY MODULATION PRINCIPLES 169
5.1 Introduction 169
5.2 Modulated Wave 170
5.2.1 Frequency Deviation 171
5.2.2 Percentage of Modulation 172
5.3 FM Radio Frequency Band 173
5.3.1 Radiation Standards 174
CONTENTS

5.4 Direct Frequency Modulation 175
5.4.1 Deviation Sensitivity 178
5.4.2 Carrier Frequency Tolerances 178
5.4.3 The Effects and Limits of the Audio Frequency 179
5.4.4 Modulation Index 181
5.4.5 FM Wave Equation 181
5.4.6 Bandwidth of the FM Wave 186
5.4.7 Deviation Ratio 186
5.4.8 The Voltage Distribution in the FM Wave 187
5.4.9 Power in the Modulated FM Wave 188
5.4.10 Narrowband FM 189
5.4.11 Preemphasis (Deemphasis) 189
5.5 Indirect Frequency Modulation (Phase Modulation) 192
5.6 Carrier Phase in the Frequency-Modulated Wave 196

CHAPTER SIX
FREQUENCY-MODULATED TRANSMITTERS

6.1 Introduction 201
6.2 Carrier Oscillator 201
6.2.1 Reactance Modulator 205
6.3 Frequency Changers 209
6.3.1 Mixers 209
6.3.2 Modulators 209
6.3.3 Converters or Translators 209
6.3.4 Dividers 211
6.3.5 Multipliers 211
6.4 Power Amplifiers 214
6.5 Feedback Frequency Control 216
6.6 Phase Modulator 218
6.7 Carrier Null 219
6.8 Transmitter Adjustments 220

CHAPTER SEVEN
FM RECEIVERS

7.1 Introduction 225
7.2 RF Amplifier 226
7.2.1 Noise in RF Amplifiers 227
7.3 Local Oscillator 233
7.4 Mixer Amplifier 234
7.5 IF Amplifiers 235
7.6 Limiters 236
7.7 FM Detectors 237
7.7.1 Slope Detector 237
7.7.2 Dual Slope Detector 238
7.7.3 The Discriminator 239
CONTENTS
9.2.1 Pure Resistance Line 301
9.2.2 Resistance Circle Sets 302
9.2.3 Reactance Circles (Arcs) 302
9.2.4 Wavelength Scales 305
9.2.5 Reflection Coefficient 305
9.2.6 Reflection Magnitude 306
9.3 Normalized Impedances 306
9.3.1 Standing Wave Ratio Circle 307
9.3.2 Load Line 307
9.4 Matching Load Impedances 309
9.5 Problem Solving Procedures 310
9.5.1 Explanation of the Procedures 312
9.6 Directional Couplers 314
9.6.1 VSWR Meter 314
9.7 Slotted Lines 315
9.7.1 Matching with a Slotted Line 318
9.7.2 Unknown Z, with a Slotted Line 319
9.7.3 Matching Transformers for Complex Load Impedances 320
9.7.4 Reflection Coefficient, Magnitude, and Angle 320
9.7.5 Line Input Impedance 321
9.8 Lossy Lines 322
9.9 Multiple-Stub Tuning 325
9.10 Other Uses of the Smith Chart 330
9.11 Carter Chart 330

CHAPTER TEN
ANTENNAS
333
10.1 Introduction 333
10.1.1 Reciprocity Theorem 334
10.2 Half-Wave Dipole Antenna 334
10.2.1 The Radiated Wave 335
10.2.2 Polarization 336
10.2.3 Radiation Patterns 337
10.2.4 Antenna Impedance 339
10.2.5 Antenna Size 340
10.3 Folded Dipole 341
10.4 Conical Antenna 343
10.5 Turnstile Antenna 345
10.6 Parasitic Array Antennas 345
10.6.1 Driven Arrays 351
10.6.2 Log-Periodic Array 355
10.7 Antenna Stacking 358
10.8 Multiband Antennas 361
10.9 Quad Antennas 362
10.10 Helical Beam Antennas 363
10.11 Marconi Antenna 365
10.12 Impedance Matching to Antennas 370
CONTENTS

10.12.1 Transformer Matching 370
10.12.2 Matching Stubs 371
10.12.3 "T" Match and Delta Match 372
10.12.4 Gamma Match 374
Parabolic and Corner Reflectors 375
Circular Polarization 376
10.15 Model Antennas 378

CHAPTER ELEVEN
WAVE PROPAGATION

11.1 Introduction 383
11.2 Ground Waves 383
11.3 Sky Waves 385
11.3.1 Radio Horizon 386
11.3.2 Ionospheric Layers 387
11.3.3 Power Density 389
11.3.4 Electric Field Strength 390
11.3.5 Skip Wave 391
11.4 Space Waves 394

CHAPTER TWELVE
MICROWAVE SYSTEMS AND DEVICES

12.1 Introduction 399
12.2 Microwave System 399
12.3 Waveguide 403
12.3.1 Attenuation 406
12.3.2 Waveguide Selection 407
12.3.3 Coupling Methods 408
12.3.4 Modes 409
12.3.5 Slots in Waveguides 412
12.3.6 Working Factors of Waveguide 413
12.3.7 Input Impedance to the Guide 415
12.3.8 Power Limits of Waveguide 415
12.3.9 Corners, Bends, and Tees 416
12.3.10 Directional Couplers 419
12.3.11 Planned Waveguide Obstructions 422
12.4 Horn Antennas 423
12.5 Parabolic Reflectors 428
12.6 The Dielectric Rod Antenna 435
12.7 Resonant Cavities 438
12.7.1 Transit Time 439
12.7.2 Electron Bunching 440
12.7.3 Klystron 440
12.7.4 Magnetrons 443
12.7.5 Traveling Wave Tube (TWT) 446
CONTENTS

12.8 Parametric Amplifiers ........................................ 449
12.9 Circulators. Magic Tees, and Hybrid Rings .......... 451
12.10 Gas Discharge Tubes ........................................ 452
12.11 Bolometers ......................................................... 453
12.12 Microwave Diodes ................................................ 454
12.13 Microwave Field-Effect Transistors ...................... 455
12.14 Stripline and Microstrip Circuits ........................ 456

CHAPTER THIRTEEN
THE COMMUNICATIONS SATELLITE

13.1 Introduction .......................................................... 463
13.2 Satellite Orbit ....................................................... 465
13.3 Satellite Position ................................................... 465
13.4 Linkages ............................................................... 466
13.4.1 Up-Link ........................................................... 466
13.4.2 Down-Link ....................................................... 467
13.4.3 Cross-Link ....................................................... 468
13.5 Assignable Satellite Frequencies ............................ 469
13.6 Inside the Satellite .................................................. 469
13.6.1 Transponder ..................................................... 470
13.6.2 Antenna Systems ............................................... 474
13.6.3 Power Package .................................................. 475
13.6.4 Station Keeping ................................................ 476
13.7 Forms of Modulation .............................................. 477
13.8 Free-Path Space Losses ........................................... 478
13.9 Ground Station ...................................................... 480
13.9.1 Aligning the Satellite Dish ................................ 482
13.10 Some Future Trends ............................................... 484

CHAPTER FOURTEEN
FIBER OPTICS

14.1 Introduction .......................................................... 487
14.2 Modulation Techniques ........................................... 487
14.3 Frequencies ............................................................ 488
14.4 Fiber Optic Cables ................................................... 490
14.4.1 Refraction ....................................................... 491
14.4.2 Numerical Aperture ........................................... 493
14.4.3 Graded Index Cables ........................................ 494
14.4.4 Single Mode versus Multimode .......................... 495
14.4.5 Pulse Dispersion ................................................ 496
14.4.6 Cable Construction ............................................. 497
14.4.7 Cable Losses ...................................................... 500
14.5 Connectors ............................................................ 503
14.6 Advantages/Disadvantages ...................................... 507
CONTENTS
14.7 Bit Error Rate 509
14.7.1 Minimum Input Signal 509
14.8 Flux Budget 510
14.9 Rise Time Budget 513
14.10 Light Sources 515
14.10.1 Lasers 520
14.11 Light Detectors 524
14.6.1 Pin Diodes 526
14.6.2 Avalanche Diodes 528
14.12 System Components 530

CHAPTER FIFTEEN
DIGITAL MODULATION 535
15.1 Introduction 535
15.1.1 Codes 535
15.2 Data Forms 536
15.3 Transmission Modes between Stations 538
15.4 Networks 539
15.4.1 Point-to-Point 539
15.4.2 Star 540
15.4.3 Ring 540
15.4.4 Bus 540
15.5 Telephone Lines 541
15.6 Dial Up Lines 543
15.7 Dedicated Lines 545
15.8 Acoustical Couplers 546
15.9 Data Communications Systems 546
15.10 Parity 548
15.11 Asynchronous and Synchronous Transmission 548
15.12 UARTS and ACIAS 550
15.13 RS232C Interconnect Cable (CCIT V.24 and V.28) 555
15.13.1 Drivers/Terminators 558
15.13.2 System Status 559
15.14 Modems 560
15.14.1 Low-Speed Modems 560
15.14.2 Medium-Speed Modems 563
15.14.3 High-Speed Modems: 8 PSK 567
15.15 Dual Four-Level Converters 572
15.16 Hybrid Devices 574
15.17 Loopback Testing 576
15.18 Protocol 577
15.18.1 Select 578
15.18.2 Polling 578
15.18.3 Responses 578
15.18.4 Asynchronous 579
15.18.5 Synchronous (Bisync or BSC) 579
15.18.6 High-Level Data Link Control (HDLC) 581
CONTENTS

15.19 Analog to Digital Conversion .......................................................... 586
15.19.1 Pulse Amplitude Modulation (PAM) ........................................ 587
15.19.2 Time-Division Multiplexing (TDM) ............................................ 589
15.19.3 Pulse Width Modulation (PWM) .................................................. 593
15.19.4 Pulse Position Modulation (PPM) ............................................... 594
15.20 Frequency Division Multiplexing (FDM) ....................................... 593
15.20.1 Decoding the FDM Signals ........................................................ 598
15.21 Cellular Communications .................................................................. 599

CHAPTER SIXTEEN
TELEVISION

16.1 Introduction ...................................................................................... 607
16.2 Scanning Principles .......................................................................... 607
16.3 Deflection Systems .......................................................................... 610
16.3.1 High Voltage .................................................................................. 613
16.4 Video Picture Signal .......................................................................... 614
16.4.1 Blanking and Synchronizing Pulses .......................................... 615
16.4.2 Positive/Negative Picture Phase ................................................ 617
16.5 Vestigial Sideband Transmission .................................................. 618
16.5.1 Sound Carrier ................................................................................. 619
16.5.2 Channel Assignments .................................................................. 620
16.6 Receiver Block Diagram .................................................................. 620
16.6.1 Tuner ............................................................................................... 620
16.6.2 IF Amplifiers .................................................................................. 622
16.6.3 Automatic Gain Control ................................................................ 623
16.6.4 Video Amplifiers ............................................................................ 624
16.6.5 Sound Carrier ................................................................................. 625
16.6.6 Synchronizing Circuit .................................................................. 625
16.7 Color .................................................................................................. 626
16.7.1 Subcarrier Modulation .................................................................. 627
16.8 Multichannel Television Sound (MTS): TV Stereo ......................... 628

SMITH CHARTS .................................................................................. 635

ADDITIONAL MAXWELL MACMILLAN
INTERNATIONAL EDITIONS IN
ENGINEERING

Astus PRINCIPLES OF BIOMEDICAL INSTRUMENTATION & MEASUREMENT
Bugat ELECTRONIC DEVICES & CIRCUITS/2e
DeGanno ENGINEERING ECONOMY/5e
Floyd ELECTRONIC DEVICES/2e
Floyd ELECTRONICS FUNDAMENTALS/2e
Floyd PRINCIPLES OF ELECTRIC CIRCUITS/3e
Floyd PRINCIPLES OF ELECTRIC CIRCUITS, ELECTRON FLOW VERSION/2e
Mayer ELECTRONIC MATERIALS SCIENCE
Proakis INTRODUCTION TO DIGITAL SIGNAL PROCESSING
Shackelford INTRODUCTION TO MATERIALS SCIENCE FOR ENGINEERS/2e
Taha OPERATIONS RESEARCH/4e
Tocci FUNDAMENTALS OF ELECTRONIC DEVICES/4e
Shearer DYNAMIC MODELING & CONTROL OF ENGINEERING SYSTEMS
Webb INDUSTRIAL CONTROL ELECTRONICS
Wolf STATICS & STRENGTH OF MATERIALS
Young ELECTRONIC COMMUNICATION TECHNIQUES/2e
Ziemer SIGNALS & SYSTEMS CONTINUOUS & DISCRETE/2e

DING EN

Ingeniería Eléctrica