FUNDAMENTALS OF

DIGITAL TELEVISION
TRANSMISSION
FUNDAMENTALS OF
DIGITAL TELEVISION
TRANSMISSION

GERALD W. COLLINS, PE
GW Collins Consulting

A Wiley-Interscience Publication
JOHN WILEY & SONS, INC.
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Library of Congress Cataloging-in-Publication Data:

Collins, Gerald W.
Fundamentals of digital television transmission / Gerald W. Collins.
p. cm.
Includes index.
ISBN 0-471-39199-9 (cloth : alk. paper)
1. Digital television. I. Title.

TK6678 .C63 2000

621.388 — dc21 00-035919

Printed in the United States of America.

10 9 8 7 6 5 4 3 2 1
 To God
who created the electromagnetic force
and
the law that governs its operation in communications systems
and
To my beautiful wife Wilma
who, after 39 years of marriage,
still wonders why I’m thinking about my work!
CONTENTS

Preface xi

Acknowledgments xiii

1 Digital Television Transmission Standards 1

ATSC terrestrial transmission standard, vestigial sideband modulation,
DVB-T transmission standard, ISDB-T transmission standard, channel
allocations, antenna height and power, MPEG-2

2 Performance Objectives for Digital Television 21

System noise, external noise sources, transmission errors, error vector
magnitude, eye pattern, interference, cochannel interference, adjacent
channel interference, analog to digital TV, transmitter requirements

3 Channel Coding and Modulation for Digital Television 43

Data synchronization, randomization/scrambling, forward error
correction, interleaving, inner code, frame sync insertion, quadrature
modulation, 8 VSB, bandwidth, error rate, COFDM, flexibility,
bandwidth

vii
viii CONTENTS

4 Transmitters for Digital Television 67

Precorrection and equalization, up conversion, precise frequency
control, RF amplifiers, solid-state transmitters, RF amplifier modules,
power supplies, power combiners, Wilkinson combiner, ring
combiner, starpoint combiner, cooling, automatic gain or level control,
ac distribution, transmitter control, tube transmitters, tube or
solid-state transmitters, performance quality, retrofit of analog
transmitters for DTV

5 Radio-Frequency Systems for Digital Television 98

Constant-impedance filter, output filters, elliptic function filters,
cavities, channel combiners

6 Transmission Line for Digital Television 117

Fundamental parameters, efficiency, effect of VSWR, system AERP,
rigid coaxial transmission lines, dissipation, attenuation, and power
handling, higher-order modes, peak power rating, frequency response,
standard lengths, corrugated coaxial cables, wind load, waveguide,
bandwidth, waveguide attenuation, power rating, frequency response,
size trade-offs, which line? waveguide or coax? pressurization

7 Transmitting Antennas for Digital Television 150

Antenna patterns, elevation pattern, mechanical stability, null fill,
azimuth pattern, slotted cylinder antennas, gain and directivity, power
handling, antenna impedance, bandwidth and frequency response,
multiple-channel operation, types of digital television broadcast
antennas, antenna mounting

8 Radio-Wave Propagation 199

Free-space propagation, distance to the radio horizon, refraction,
multipath, ground reflections, surface roughness, effect of earth’s
curvature, Fresnel zones, linear distortions, diffraction, fading,
undesired signal, field tests, Charlotte, North Carolina, Chicago,
Illinois, Raleigh, North Carolina
CONTENTS ix

9 Test and Measurement for Digital Television 245

Power measurements, average power measurement, calorimetry,
power meters, peak power measurement, measurement uncertainty,
testing digital television transmitters

Symbols and Abbreviations 251

Index 261
PREFACE

Many engineers familiar with analog television broadcast systems are now faced
with designing, operating, and maintaining digital television systems. A major
reason for this introductory book is to make the transition from analog to digital
television broadcasting as painless as possible for these engineers. The emphasis is
on radio-frequency (RF) transmission, those elements of the system concerned with
transmitting and propagating the digitally modulated signal. I begin with the digital
signal as it emerges from the transport layer and end with the RF signal as it arrives
at the receiver. The emphasis is on factors affecting broadcast system performance.
The scope of this book is necessarily limited; some topics, such as studio-
to-transmitter links and receivers are not covered. It is intended as a self-study
resource by the broadcast system engineer, as well as a reference for the design
engineer, system engineer, and engineering manager. An index is included to
make it a more useful resource for future reference. It may be used as a text for
a formal training class.
Most people would agree that a useful engineering tool must include some
mathematics. For this reason, and to make the presentation as clear as possible,
concepts have been described verbally, mathematically, and in many cases,
graphically. The mathematics used include algebra, trigonometry, and a small
amount of calculus. For those not interested in the mathematical formulation, the
charts and graphs should be sufficient to grasp the key points.
For those who wish to probe further, extensive footnotes are provided. These
not only provide much more detail but are my attempt to give credit to the many
workers who have brought digital television to its present state of maturity. Even
with ample footnotes, I may have failed to give credit to all who deserve it. This
is by no means intentional; the references included are simply those sources of
which I am aware.
xi
xii PREFACE

To the extent possible I have used the mathematical symbols most commonly
used for the quantities discussed. However, the literature for the many subsystems
comprising a digital television transmission system use common symbols to
represent a large number of the quantities. To avoid confusion, I have added
subscripts and used alternative type fonts to distinguish such quantities where
necessary. When I found it necessary to use a nonstandard symbol, I attempted
to make the relationship between the quantity and its symbol as intuitive as
possible.
To the extent that information was available to me, I have discussed the
American ATSC, the European DVB-T system, and Japan’s ISDB-T system. My
personal experience and library are heavily biased in the direction of the ATSC
and DVB-T systems, however, a fact that will readily be apparent to the reader.
The information presented should not be considered an endorsement of a specific
system for any particular country or group of countries. There are many factors
to be considered when selecting a transmission system, not all of which are
determined by performance parameters such as transmitter peak-to-average ratio
or threshold carrier-to-noise ratio. These include the type of network, program
and service considerations, and the extent of the use of mobile receivers, as well
as language, industrial policy, and other issues. The information presented is
factual to the best of my understanding. Readers are left to draw the appropriate
conclusions for their applications.
My personal design background is in antennas, analog transmitter systems,
passive RF components, and propagation. When the transition to digital television
began, it became necessary to educate myself with regard to digital modulation
techniques, system design, and testing. This has required collaboration with many
experts and the study of many reports and papers. This book is the result of that
effort. If in some respect the presentation of any topic is incomplete, I take full
responsibility.
The implementation of digital television is a process that will continue for
many years to come. The transition periods will take up to 15 years in some
countries. The process will not start in Japan until after 2003. In the United States
the transition period has started and is mandated to be short. However, stations
whose initial channel is outside the core spectrum will be required to move to
a core channel after the transition. Those whose analog and digital channel is
inside the core will be permitted to chose their permanent channel. It is hoped
that this book will be helpful to those who are designing and implementing these
systems, both now and in the future.

JERRY COLLINS
December 1999
ACKNOWLEDGMENTS

I most certainly do not claim originality for much of the material included in
this book. In fact, the story of digital television builds on the many contributions
of workers since the beginning of radio and television transmission. Rather, this
book represents the result of my own attempt to understand and manage the
development of digital television broadcast equipment since 1989. I am especially
grateful to my former colleagues and the management of Harris Corporation
Broadcast Division for their outstanding efforts. Together we participated in
the process of developing digital television standards, designing equipment, and
testing broadcast systems. It is to them that I owe so very much.
In naming some, I’m sure I will miss some important contributors. However,
I must mention the very beginning of our work when Bob Plonka, Jim Keller,
I, and others worked with Charlie Rhodes of the ATTC to develop the RF test
bed by which the proponent transmission systems were tested. Bob and Jim
have continued their work developing, implementing, and testing new designs
and production equipment for Harris. Charlie’s name is almost synonymous with
DTV transmission. As soon as it was clear that the 8 VSB system would be
the standard for the United States, I involved others in my R&D group in the
development of the first series of 8 VSB exciters. These fine engineers included
Dave Danielsons, Ed Twitchell, Paul Mizwicki, Dave Nickell, Dave Blickhan,
Bruce Merideth, and Joe Seccia. The system engineering skills of Bob Davis
were vital. We started the work on power amplifier development soon after the
exciter. This could not have been accomplished without the able contributions of
the engineers at our sister facility in Cambridge, England, under the leadership of
Dave Crawford and Barry Tew. Dmitri Borodulin joined us in Quincy, Illinois for

xiii
xiv ACKNOWLEDGMENTS

solid state PA development, along with Jim Pickard who made many contributions
to the design of the IOT amplifier. I wish to emphasize the role of Harris
management — especially my good friend Bob Weirather — in the development
process. Without their support and encouragement we would have accomplished
very little. Finally, my sincere thanks to Bob for his review of the manuscript
and his constructive comments.