digital terrestrial television broadcasting - ITU

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DTTB HANDBOOK DIGITAL TERRESTRIAL TELEVISION BROADCASTING
IN THE
VHF/UHF BANDS Version 1.02 Radiocommunication Bureau © ITU 2013 All rights reserved. No part of this publication may be reproduced, by any
means whatsoever, without the prior written permission of ITU.
OVERALL INTRODUCTION
In view of their many advantages, digital television systems are destined
to replace the analogue television systems which have been used for more
than half a century to provide sound and vision services to countless
millions of people around the world. The ITU-R has decided to provide
guidance to engineers responsible for the implementation of digital
terrestrial television broadcasting (DTTB) in the form of a single handbook
which combines material dealing with both systems and planning aspects of
this new, exciting and yet highly complex topic. The result is a rather
large volume and anyone interested in the subject of digital television
should find something in it which is both informative and useful. It is not to be expected that all existing analogue television services
will be replaced by digital services overnight. Rather, it will take
several, perhaps many, years for this to happen. It is hoped that this
handbook will continue to provide information and help throughout the
interesting years which lie ahead.
PART 1 SYSTEMS PART PART 1
TABLE OF CONTENTS Page CHAPTER 1 - Introduction 7 1.1 Scope 7 1.2 Background 7 CHAPTER 2 - An overview of the DTTB model 9 2.1 The challenge 9 2.2 The ITU DTTB model 10 CHAPTER 3 - Video and audio source coding 13 3.1 Definitions 13 3.1.1 Source and channel coding 13 3.1.2 Source coding 13 3.1.3 Progressive scanning 13 3.1.4 Square pixels 13 3.2 Benefits 13 3.3 Low bit rate video coding and service quality 14 3.4 Examples of video scanning standards 14 3.5 Video compression and coding [1] [2] [3] 14 3.5.1 Introduction 14 3.5.2 Introduction to MPEG 14 3.5.3 Digital compression techniques 15 3.5.4 Inter-frame prediction coding and motion compensation 16 3.5.5 Intra-frame coding 18 3.5.6 Discrete cosine transform (DCT) coding 18 3.5.7 Coefficient quantization 19 3.5.8 Run length coding 21 3.5.9 Variable length coding 21 3.5.10 MPEG video encoder 22 3.5.11 I, B & P-frames 23 3.6 MPEG-2 video bit stream 24 Page 3.7 Audio compression and coding 29 3.7.1 Introduction 29 3.7.2 Characteristics of a DTTB audio system 30 3.7.3 Overview of the DTTB audio system 32 3.7.4 Overview and basics of audio compression 33 3.8 The ISO/IEC IS 13818-3 (MPEG-2) Layer II system 34 3.8.1 Introduction 34 3.8.2 Principal user features of ISO/IEC 13818-3 Layer II 35 3.8.3 MPEG-2 Layer II technical details 43 3.8.4 Conclusion 46 3.9 AC-3 system description 46 3.9.1 Introduction 46 3.9.2 AC-3 technical details 47 3.9.3 Bit stream syntax 50 3.9.4 Loudness and dynamic range 51 3.9.5 Main, associated, and multilingual services 54 3.9.6 Conclusion 58 3.10 Ancillary Data 58 3.10.1 Teletext 59 3.10.2 Programme subtitles 59 3.10.3 Broadcast multimedia ervices 59 3.11 The MPEG-2 multiplexing structure 59 3.11.1 Packetized elementary stream 61 CHAPTER 4 - Service multiplex and transport 65 4.1 Available structures 65 4.1.1 ATM 65 4.1.2 MPEG-2 65 4.1.3 ISDB 66 4.2 Multiplexing of video, audio, and data 66 4.2.1 Introduction 66 4.2.2 Program versus Transport Stream multiplexing 67 4.2.3 Advantages of the fixed length packetization approach 68 4.2.4 Overview of the transport subsystem 69 Page 4.3 Higher level multiplexing functionality 70 4.3.1 Single program transport multiplex 70 4.3.2 System multiplex 71 4.4 The PES packet format 72 4.5 The packetization approach and functionality 80 4.5.1 Overview 80 4.5.2 The "link" layer 81 4.5.3 The Adaptation layer 84 4.5.4 PSIs and the pointer_field. 88 4.6 Features and services 92 4.6.1 Introduction 92 4.6.2 Audio compression types and language identification 92 4.6.3 Program information 92 4.6.4 Captioning 92 4.6.5 Closed captioning 92 4.6.6 Program source and program identification 93 4.6.7 Conditional access identification 93 4.6.8 Picture structure information 93 4.6.9 Colorimetry 93 4.6.10 Colour field identification 93 4.6.11 Scene changes and clean-insertion points 93 4.6.12 Field/frame rate and film pull-down 94 4.6.13 Pan and scan 94 4.6.14 Random entry into the compressed bit stream 94 4.6.15 Local program insertion 94 4.6.16 Individual programme identification 95 4.6.17 Other channel information 95 CHAPTER 5 - Physical Layer - Channel coding and modulation 97 5.1 Introduction 97 5.2 Spectral efficiency 97 5.3 Modulation techniques 98 5.3.1 General considerations 98 5.3.2 Single-carrier modulation (SCM) 98 5.3.3 Multi-carrier modulation (MCM) 99 Page 5.4 Channel coding (error correction coding) 105 5.5 Comparisons of early implementations of single- and multi-carrier
systems 106 5.5.1 Impulse interference 107 5.5.2 Multipath distortion 107 5.5.3 Co-channel interference from analogue TV 108 5.5.4 Peak and average power ratio issues 109 5.6 Coverage issues 110 5.6.1 Hierarchical transmission 110 5.6.2 Multi-transmitter systems 111 CHAPTER 6 - Systems overview 113 6.1 The ATSC system 113 6.2 The DVB-T system 113 6.3 The ISDB-T system 115 6.3.1 Transmission bandwidths of ISDB-T 115 6.3.2 Hierarchical transmission 116 6.3.3 Partial reception 116 6.3.4 Multiplex for Hierarchical Transmission 117 6.3.5 Functional Block Diagram of the ISDB-T 118 6.3.6 Transmission parameters 119 CHAPTER 7 - List of ITU-R Recommendations relating to digital
terrestrial television broadcasting (DTTB) 125 PART 2
(See page 127) CHAPTER 1 INTRODUCTION 1.1 Scope
This part of the Handbook provides tutorial information and an overview on
the subject of digital terrestrial television broadcasting (DTTB) systems.
It describes a system designed to transmit high quality audio and video
services over a single 6, 7, or 8 MHz broadcasting channel and provides a
tutorial on the technologies that support the Recommendations developed by
the former Task Group 11/3 during the period 1992 through 1996. It also
provides a summary of the state of development in systems specifications
and plans for service implementation up to the end of 1998. 1.2 Background
The majority of established broadcasters use terrestrially-based emission
systems operating in the VHF/UHF frequency bands. The issue of delivery of
high-definition television (HDTV) picture signals and associated sound
services within a single 6, 7, or 8 MHz VHF/UHF channel resulted in a
review of the application of digital coding techniques in terrestrial
transmission. The migration from a television service dependent primarily on the
application of analogue technologies to one that is based on digital
technologies has been evolving over the past thirty years. This television
service migration is part of a natural outgrowth of the convergence of the
television, telecommunications, and computer arts and sciences through the
shared use of digital technology. The input and output signals of television systems, at the camera and at
the receiver, respectively, are inherently analogue. Thus, the question
"why digital?" is a natural one. While signal degradations in the analogue signal are cumulative and the
characteristics of the degradations make them difficult to distinguish from
the video signal, the ability to regenerate a digital pulse train exactly
renders the digital signals theoretically immune to impairments from
external sources. Digital bit streams can be interleaved within a single
channel. This interleaving process allows fo