I 0 i 0

Te I ec ⁰ mm un i cati ⁰ ns Transmission

Engineering

Telecommunica tions Transmission

Engineering

Volume 1 - Principles

Second Edition

Technical Personnel

American Telephone and Telegraph Company, Bell Telephone Companies,

and

Bell Telephone Laboratories

Bell System Center for Technical Education

Chapter 6, Copyright © 1964

'Chapters 7 and 8 Copyright © 1959, 1964, 1970 by Bell Telephone Laboratories, Inc.

Prepared for Publication by Western Elect'ric Company, Inc.

Technical Publications Winston-Salem, North Carolina

FIRs'r :BJDITION 1974

SECOND EDITION 1977

Printed in the United States of America

Telecommunications Transmission

Engineering

Introduction

Co.mmunicatio.n Engineering is co.ncerned with the planning, design, implementatio.n, and o.peratio.n o.f the netwo.rk o.f channels, switching machines, and user terminals required to. pro.vide co.mmunicatio.n between distant Po.ints. Transmissio.n Engineering is the part o.f Co.mmunicatio.n Engineering which deals with the channels, the trans- missio.n systems which carry the channels, and the co.mbinatio.ns o.f the many types o.f channels and systems which fo.rm the netwo.rk o.f facilities. It is a discipline which co.mbines many skills fro.m science and technolo.gy with an understanding o.f eco.no.mics, human facto.rs, and system o.peratio.ns.

This three-volume bo.o.k is written fo.r the practicing Transmissio.n Eng,ineer and fo.r the student o.f transmissio.n engineering in an under- graduate curriculum. The material was planned and o.rganized to.

make it useful to. anyo.ne co.ncerned with the many facets o.f Co.mmuni- catio.n Engineering. Of necessity, it represents a view o.f the status o.f co.mmunications techno.Io.gy at a specific time. The reader sho.uld be co.nstantly aware o.f the dynamic nature o.f the subject.

Vo.lume 1, Principles, co.vers the transmissio.n engineering prin- ciples that apply to. co.mmunicatio.n systems. It defines the charac- teristics of various types o.f signals, describes signal impairments arising in practical channels, pro.vides the basis fo.r understanding the relatio.nships between a communicatio.n network and its compo.nents, and pro.vides an appreciatio.n o.f how transmissio.n o.bjectives and aohievable perfo.rmance are interrelated.

Volume 2, Facilities, emphasizes the applicatio.n of the principles of Vo.lume 1 to. the design, implementatio.n, and o.peratio.n of trans- missio.n systems and facilities which fo.rm the teleco.mmunications

iii

network. The descriptions are illustrated by examples taken from modern types of facilities most of which represent equipment of Bell Laboratories design and Western Electric manufacture; these examples are used because they are familiar to the authors.

Volume 3, Networks and Services, shows how the principles of Volume 1 are applied to the facilities described in Volume 2 to pro- vide a variety of public and private telecommunication services. This volume reflects a strong Bell System operations viewpoint in its con- sideration of the problems of providing suitable facilities to meet customer needs and expectations at reasonable cost.

The material has been prepared and reviewed by a. large number of technical personnel of the American Telephone and Telegraph Company, Bell Telephone Companies, and BeH Telephone Labora- tories. Editorial support has been provided by the Technical Publica- tions Organization of the Western Electric Company. Thus, the book represents the cooperative efforts of many people in every major organization of the Bell System and it is difficult to recognize indi- vidual contributions. One exception must be made, however. The material in Volume 1 and most of Volume 2 has been prepared by Mr. Robert H. Klie of the Bell Telephone Laboratories, who was associated in this endeavor with the Bell System Center for Technical Education. Mr. Klie also coordinated the preparation of Volume 3.

C. H. Elmendorf, III Assistant Vice President - Transmission Division.

American Telephone and Telegraph Company

Volume 1 - Principles

Preface

This volume, comprised of five sections, covers the basic principles involved in transmitting communication signals over Bell System facilities. Section 1 provides a broad description of the transmission environment and an overview of how transmission parameters affect the performance of the network. The second section consists of a review of most of the mathematical relationships involved in trans- mission engineering. A wide range of subj ects is discussed, from an explanation of and justification for the use of logarithmic units (decibels) to a summary of information theory concepts.

The third section is devoted to the characterization of the prin- cipal types of signals transmitted over Bell System facilities. Speech, television, PICTUREPHONE®, digital and analog data, address, and supervisory signals are described. Multiplexed combinations of signal types are also characterized. The fourth section describes a variety of impairments suffered by signals transmitted over practical chan- nels, which have imperfections and distortions. Also discussed are the units in which impairments are expressed and the methods by which they are measured. The fifth section discusses the derivation of transmission objectives, gives many established values of these objectives, and relates them to requirements applied to system design and operation. The section concludes with a chapter on international communications and internationally applied transmission objectives.

v

Contents

Introduction Preface

SECTION 1 BACKGROUND

Chapter 1. The Transmission Environment 1-1 Transmission Paths

The Station Set ... . Customer Loops Switching Machines Trunks ... ~., .. .

1-2 Switching Arrangements ... . The Local Switching Hierarchy The Toll Switching Hierarchy

1-3 Impact of System Multiplicity on Network Performance 1-4 Maintenance and Maintenance Support ...

Chapter 2. Introduction To Transmission ... .

iii

v 1

3 3 4 4 5 7 8 8 10 14 16 18

2-1 Message Signals ... 18

Speech. . . 19

Program... ... 20

Video ... 20

Data and Facsimile ... 21

Control Signals ... . . . 22

2-2 Channels ... . 23

2-3 Voice-Frequency (VF) Transmission ... . 25 25 27 Modes of Voice-Frequency Transmission

Voice-Frequency Repeaters ...

2-4 Carrier Systems ... . High-Frequency Line Equipment Modulating Equipment .... . Multiplex Equipment ... . 2-5 Ancillary Equipment and Functions

vii

28 31 32 32 33

SECTION 2 ELEMENTS OF TRANSMISSION ANALYSIS 35

Chapter 3. Fundamentals of Transmission Theory 37

37 39 45 3-1 Power and Voltage Relations in Linear Circuits ., ... .

The Decibel ... . Loss, Delay, and Gain ... . 3-2 Transmission Level Point ... .

Commonly Used TLPs ... . Illustrative Applications of TLP ... . 3-3 Signal and Noise Measurement ... .

Volume ... . Noise ... .

Display Techniques ... .

48 49 51 53 54 56 58

3-4 Addition of Power in DB ., 59

Chapter 4. Four-Terminal Linear Networks ... 63

64 64 65 4-1 The Basic Laws Ohm's Law ... . Kirchoff's Laws ... . 4-2 Application and Theorems ... 67

Equivalent Networks ... . . . . . . . 67

Thevenin's, or Pollard's, Theorem .. . . . 69

Superposition Theorem ... 70

Compensation Theorem ... 72

4-3 Network Impedance Relationships ... ... 73

Image Impedance ... 73

T-Network Equivalent ... 75

Transfer Effects ... 76

Sending-End Impedance ... . . . 78

Alignment Charts ... . . . 85

Insertion Loss and Phase Shift . . . . . . 90

Return Loss ... 90

Echo - Magnitude and Delay ... 92

Power Transfer '" . . . 94

Stability . . . 98

4-4 Network Analysis ... 100

Mesh Analysis. . . 100

Nodal Analysis ... 102

Determinants ... 103

Matrix and Linear Vector Space Analyses ... 103

4-5 Transformers ... 104

Impedance Matching ... 104

Separating and Combining ... 106 4-6 Resonant Circuits

4-7 Filters

109 110

Contents ^ix

Chapter 5. Transmission Line Theory .. 115

5-1 Discrete Component Line Simulation . . . 115

Characteristic Impedance ... 117

Attenu~tion Factor ... 119

Propagation Constant ... 120

5-2 Line With Distributed Parameters ... 121

Characteristic Impedance ... 122

Propagation Constant ... 123

Attenuation Factor ... 124

Velocity of Propagation ... 125

Reflections ... 125

5-3 Loaded Lines . . . .. 134

Analysis ... 134

Inductive Loading ... 136

5-4 Coaxial Cable ... 139

Chapter 6. Wave Analysis ... . 142

6-1 Instrumentation ... . 143

6-2 Periodic Signals ... 146

Fourier Series Representation ... 146

The (sin x) Ix Function. . . 156

6-3 N onperiodic Signals ... . The Fourier Transform Pair ... . Transmission Response ... . 157 157 160 Chapter 7. Negative Feedback Amplifiers ... 168

7-1 The Principle of Negative Feedback 168 7-2 Applications of Feedback ... . 169

7 -3 Benefits of Feedback ... 170

7-4 Circuit Configurations ... 172

Series and Shunt Feedback ... . . . .. 173

Bridge-Type Feedback ... 174 7 -5 Design Considerations ... .

Gain and Feedback ... . Nonlinear Distortion and Overload ... . Noise and Terminations ... . ... . Summary ... .

177 177 180 184 186

Chapter 8 Modulation 188 8-1 Propertie,s of Amplitude-Modulated (AM) Signals

Double Sideband with Transmitted Carrier ... . Double Sideband Suppressed Carrier ... . S,ingle Sideband ... . ... . Vestigial Sideband ... .

189 193 197 197 201

8-2 Properties of Angle-Modulated Signals ... 203

Phase Modulation and Frequency Modulation 203 Phasor Representation ... 207

Average Power of an Angle-Modulated Wave ... 208

Bandwidth Required for Angle-Modulated Waves 209 8-3 Properties of Pulse Modulation ... . . . 210

Sampling . . . 211

Pulse Amplitude Modulation ... . . . 212

Pulse Duration Modulation ... 214

Pulse Position Modulation ... 215

Pulse Code Modulation ... . . . 215

Chapter 9 Probability and Statistics .. , 9-1 Elements of Probability Theory Axioms ... . Set Operations ... . 9-2 Discrete and Continuous Functions ... .. Mapping ... . Cumulative Distribution Function Probability Density Function ... . 219 221 221 222 228 228 230 231 9-3 The Principal Parameters ... 233

Expec,ted Value ... 233

Variance ... . ... , 234

Standard Deviation ... . . . 235

9-4 Sums of Random Variables ... . 237

9-5 Distribution Functions ... . . . 239

Gaussian or Normal Distribution . . . 239

Poisson Distribution ... . . . 243

Binomial Distribution ... 244

Binomial-Poisson-Normal Relationships ... 246

Log-Normal Distribution ... . . . 246

Uniform Distribution ... , 247

Rayleigh Distribution ... 249

9-6 Statistics ... 249

Central Values and Dispersions ... .. ... 249

Histogram ... 251

Sampling . . . 252

Contents xi

Chapter 10. Information Theory ²⁵⁶

257 259 260 10-1 The Historical Basis of Information Theory

10-2 The Unit of Information 10-3 Entropy ... .

10-4 The Communication System ... " . . . 264

Coding ... 265

Noise ... 265

10-5 The Fundamental Theorems ... 266

The Noiseless Channel ... 267

The Discrete Channel with Noise ... . . . 268

Channel Capacity with an Average Power Limitation 268 10-6 Channel Symmetry ... . Chapter 11. Engineering Economy 11-1 Time Value of Money The Earning Power of Money Equivalent Time-Value Expressions 11-2 Economy Study Parameters Capital Costs ... . Plant Operations Costs Dynamic Effects on Analysis ... 269 273 275 275 276 277 280 285 287 11-3 Economy Study Techniques ... . . . 291

Analytic Alternatives ... . . . 292

Study Assumptions ... . . . 294

Summary of the Comparison Study Process . . . 296

SECTION 3 SIGNAL CHARACTERIZATION 299 Chapter 12. Speech Signals ... . 301

12-1 The Single-Channel Speech Signal . . . 302

Speech Signal Energy Distribution and Channel Response 302 Single Constant-Volume Talker ... 305

Sources of Volume Variation. . . 305

Single Variable-Volume Talker ... 308

12-2 Multichannel Speech ... 311

12-3 Load Capacity of Systems ... . . . .. 314

Multichannel Speech and Overload 315 Effect of Shaped TLP Characteristics ... ... . . .. 316

12-4 Program Signals ... . 318

Chapter 13. Signalling ... . 321

323 323 325 328 332 13-1 13-2 Signalling on Loops ... . ... . Common Battery Operation. . ... . Supervision on Loops and PBX-CO Trunks Address Signalling on Loops ... . Alerting Signals on Loops ... . ... . Signalling on Trunks ... . DC Loop Signalling on Trunks .. Panel Call Indicator (PCI) System Revertive Pulsing . . . Derived DC Signalling on Trunks . A C Signalling on Trunks .. 335 336 339. 339 342 346 13-3 Out-of-Band ~igna11ing ... . 348

349 349 13-4 Out-of-Band SF Signalling ... . Out-of-Band Digital Systems ... . Special Services Signalling Tandem Signalling Links Service Demands and Plant Complexities 349 350 350 Chapter 14. Data Signals ... . 351

14-1 Digital Signal Transmission Considerations . . . 352

14-2 Signal Amplitudes ... 352

Error Rate and Signal-to-Noise Ratio ... 354

Channel Characteristics ... . . . .. 355

Digital Signal Characteristics ... . Amplitude Shift Keyed Signals Phase Shift Keyed Signals ... . Frequency Shift Keyed Signals ., 358 359 372 373 14-3 Analog Data Signals ... . . . 375

Medium-Speed Voiceband Data. . . 376

Low-Speed Medical Data ... 376

Low-Speed Analog Data ... " . . . .. 377

Chapter 15. Video Signals ... 379

15-1 Television Signals ... 379

Standard Monochrome Baseband Signals ... . . . .. 380

Baseband Color Signals ... 388

Broadcast Signals ... . . . 390

Closed Circuit Signals ... . . . . . . .. 392

15-2 Picturephone Signals ... .. . . .. 393

Scanning ... 394

Modulation ... . ... 394

Amplitude ... 396

Contents 15-3 Telephotograph Signals

Scanning. . ... . Bandwidth ..

Chapter 16. Mixed Signal Loading 16-1 Mixed Signals and Overload 16-2 Mastergroup Speech Signal Load

16-3 Mastergroup Mixed Signal Load ... . Speech and Idle Channel Signals Speech and Address Signals ...

Speech and Data Signals Speech and Video Signals 16-4 System-Signal Interactions

System Misalignment ..

Carrier and Pilot Signals ... . Compandors ... ..

TASI ... . Microwave Radio Systems

SECTION 4 IMPAIRMENTS AND THEIR MEASUREMENT Chapter 17 Noise and Crosstalk

17-1 Coupling ... .

Currents and Circuit Relationships Coupling Paths and Their Control 17 -2 Induced Noise and Crosstalk ....

17-3

17-4

Power System Noise ... .

Impulse Noise ... . Single-Frequency Interference .

Crosstalk ... .

System-Generated Noise and Crosstalk. . . . . ... . Random Noise ... . ... . Intermodulation Noise and Crosstalk

Digital Signal Noise Impairments Noise and Crosstalk Measurements

Parameters and Units - Noise Measurements ... . Speech Crosstalk Measurements ... . Digital Measurements ... .... . . . ... . Random Noise Measurements

xiii 397 397 398

399 400 401 402 402 405 406 407 407 407 407 408 408 409

410 413 413 414 416 421 421 423 424 425 427 427 431 435 436 437 438 447 449

Chapter 18. Amplitude/Frequency Response

18-1 TelephO'ne Channels - Speech Signal TransmissiO'n Channel Bandwidth ...

Circuit LO'SS and Loss VariatiO'ns Amplitude /Frequency DistO'rtiO'n Measurements ... .

18-2 TelephO'ne Channels - Data TransmissiO'n Available Bandwidth ... . Loss and Loss Changes ... . Inband DistO'rtiO'n

Measurements ... . 18-3 Wideband Digital Channels

Available Bandwidths Measurements

18-4 VideO' Channels ... .

18-5

Bandwidth ... . CutO'ff Characteristics Loss and Loss Changes Differential Gain ...

Inband DistO'rtion Measurements TransmissiO'n Systems

Bandwidth ... . Inband DistO'rtiO'n ... . LO'ss-Time VariatiO'ns ..

Chapter 19. Timing and Synchronization Errors 19-1 Frequency Offset ... .

Speech and PrO'gram Signal Impairment Digital Data Signal Impairment AnalO'g System Impairments

Digital System Impairment ... . 19-2 Other Incidental MO'dulatiO'n ..

Gain and Phase Hits ... . Jitter ... . Dropouts ... . 19-3 The SynchrO'nizing NetwO'rk ... . Chapter 20. Echo in Telephone Channels 20-1 EchO' SO'urces ... . 20-2 Nature O'f EchO' Impairments.

Speech Signals ... . Digital Data Signals ... . TelephO'tO'graph Signals ... .

455 455 456 457 458 459 459 460 461 461 462 463 464 465 465 465 466 466 467 467 468 470 471 471 472 474 474 477 477 477 478 479 479 479 480 481 482 482 486 486 491 491

Contents 20-3 Echo Measurement and Control ..

Echo Return Loss ... . Singing Return Loss ... . Echo Suppressors .... . Chapter 21. Phase Distortion ... .

21-1 Phase/Frequency Mathematical Characterization Departure From Linear Phase

Phase Delay ... . Delay Distortion .... ... . Envelope Delay ... . Envelope Delay Distortion Illustrative Characteristics Intercept Distortion

Quadrature Distortion ... . Differential Phase ... . 21-2 Phase Distortion in Telephone Channels

Phase / Frequency Impairments Quadrature Distortion

21-3 Phase Distortion in Broadband Channels Phase/Frequency Distortion

Quadrature Distortion

Differential Phase ... .

xv 492 492 494 494 496 496 496 498 499 500 501 501 501 505 509 511 511 512 513 513 513 514 21-4 Measurement, Evaluation, and Control of Phase Distortion ... 514 Phase/Frequency Measurement and Evaluation . . . 514

Phase Distortion Control .... 516

Chapter 22. Maintenance and Reliability ..

22-1 Maintenance ... . Sources of Deterioration and Failure Maintenance Systems and Equipment 22-2 Reliability· ... .

Sources of Failure ... .

Designs for Reliability ... .

Network Operating Methods and Procedures ....

SECTION 5 OBJECTIVES AND CRITERIA Chapter 23. Subjective Testing

23-1 Subjective Test Methods ... . Threshold Testing ... . Pair-Comparison Testing ... .

Comment Scale Testing - Category Judgments

520 521 522 523 526 527 529 531 533 536 537 537 538 539

23-2 Test Plan and Procedures 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 541 541 542 543 545 Setting Goals ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} Test Locale ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} Teost Conditions ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} Test Procedures ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 23-3 Data Analysis ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 546 Chapter 24. Grade of Service ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 551 24-1 A Graphic Derivation of Grade of Service ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 551 Customer Opinion Distributions ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 552 Relation of Connection Losses to Subjective Test Results ^{0 0 0 0 0 0 0 0 0 0} 553 24-2 Mathematical Derivation of Grade of Service ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 556 24-3 Uses of the Grade-of-Service Concept ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 566 Engineering Compromises ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 566 Performance Evaluation ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 568 Time Effects on Grade of Service ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 569

24-4 Loss-Noise-Echo Grade of Service ^{0 0} 570

571 573 573 574 Connection Loudness Loss and Noise Model

Talker Echo Model ^{0 0 0 0 0 0 0 0 0 0 0 0} Loss-Noise-Echo Model ^{0 0} Subjective Opinion Models

Chapter 25. Determination and Application of Objectives 577 577 25-1 Determination ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 25-2 Interpretation ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 578

Static Impairment Characteristics ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 579 Probabilistic Characteristics ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 580 Multiple Impairments ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 581 Objectives, Requirements, and Limits ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 581 25-3 Allocation ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 583 Allocation Assuming Power Addition ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 583 Cost Effects ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 584

Allocation for Digital Transmission 586

25-4 Translation ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 588 Objectives to Requirements ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 588 Transmission Level Point Translations ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 589 Indices ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 589 System Parameter Effects ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 590 Chapter 26. Transmission Objectives ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 593 26-1 Voice-Frequency Channel Objectives ^{0 0 0 0} 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 593 Bandwidth ^{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0} 594 Frequency Resonse Characteristic Distortion 594

Contents Network Loss Design Plans

Echo Objectives .... . Loss Objectives ... . Loss Maintenance Limits Message Circuit Noise ... . Impulse Noise ... . Intelligible Crosstalk ... . Single-Frequency Interference

Frequency Offset ... . Overload ... .

Miscellaneous Impairments. . ... . Telephone Station Sets ... .

xvii

595 601 603 606 607 608 609 610 611 611 611 612

26-2 Wideband Digital Signal Transmission Objectives ... . 612

613 615 Performance Evaluation ... . Design Applications ... . 26-3 Video Transmission Objectives ... . . . 617

Random Noise ... 617

Low-Frequency Noise ... 619

Impulse Noise ... ... 619

Single-Frequency Interference ... . . . 620

Echo.. . ... .... . ... ... .. . ... . . ... ... .... . . . ... .. .. 620

Crosstalk . . . 623

Differential Gain and Phase .. . . . 624

Audio/Video Delay . . . .. 624

Luminance / Chrominance Delay . . . 625

Chapter 27. Economic Factors 627 27-1 27-2 27-3 Objectives ... . Determination of Objectives .. . Allocation of Objectives Economic Objectives Design Compromises Circuit Devices ... . Circuits ... . Physical Design .... . Systems .... , .. " .... .

Application Compromises Components ... . Systems ... . Chapter 28. International Telecommunications 627 627 629 630 631 631 632 632 634 636 636 637 638 28-1 The International Telecommunication Union. . . 639

Organizational Structure of the ITU ... 641

28-2

28-3

Index

Study Groups and Working Parties ... . Characteristics of International Operations

The Evolving International Network ... . World Numbering Plan ... . Signalling ... . Traffic and Operating ... . Routing Plan ... . Transmission and Maintenance ... . ... . Transmission Parameters and Objectives ... .

Noise ... . Channel Loading . . . . ... .

642 644 644 644 646 646 647 649 650 650 652 654

Telecommunications Transmission

Engineering

Section

Background

The Bell System should be regarded as a single, huge, and far-flung telecommunications system made up of station sets, cables, switching systems, transmission systems, wires, and a conglomeration of other hardware of all sorts and sizes. This telecommunications system has grown rapidly and is still growing at a rapid rate. It has within it a large number of interconnected and interrelated systems and sub- systems, each of which was designed with an approach that provided for successful development and overall Bell System evolution. This relationship between the parts and the total has permitted the orderly growth of a giant and the rendering of telecommunications services throughout the United States, Canada, and indeed the world.

Historically, the first telephone systems consisted of two remote station sets interconnected by wires normally used for telegraph communications. As interest in telephone communication built up, the transmission capabilities of the station sets and the interconnect- ing wires were gradually improved. Soon, manually operated switch- ing systems were introduced in local communities to provide flexible interconnections among people living close together and sharing a high community of interest. These switching systems and the surrounding station sets and interconnecting wires have become known as the local plant.

The expanding local areas, the increasing demands for a wider range of services, and improvements in technology soon permitted the interconnection of one central office with another. As these interconnections increased in numbers and distances over which service had to be provided grew larger, the evolving long distance network became a separate entity known as the toll plant. Larger and more complex switching and transmission systems were designed to meet the unique needs of this part of the overall system.

Chapter 1 provides an overview of the operating Bell System plant with emphasis on the transmission and switching facilities that pro- vide nationwide telephone service. Equipment used for other services that share the message network facilities is also briefly discussed.

An introduction to transmission concepts is given in Chapter 2.

Brief descriptions of telephone, program, television, and data signals are presented, transmission terminology is defined, and basic tech- niques and modes of transmission are explained. Some specialized equipment, used to improve plant performance, is described to illustrate the interactions of various parts of the network.