ETSI EN 300 744 V1.2.1 (1999-07)

Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for digital terrestrial television

REN/JTC-DVB-87

Digitalna videoradiodifuzija (DVB) – Struktura okvirov, kodiranje kanalov in modulacija za digitalno prizemno televizijo (DVB-T)

General Information

• Status: Published
• Publication Date: 22-Jul-1999
• Technical Committee: BROADCAS - EBU/CENELEC/ETSI on Broadcasting
• Current Stage: 12 - Completion
• Due Date: 11-Jun-1999
• Completion Date: 23-Jul-1999
• Mandate: T-304
• Ref Project: SIST EN 300 744 V1.2.1:2005 - Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for digital terrestrial television

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 300 744 V1.2.1:2005
01-november-2005
Digitalna videoradiodifuzija (DVB) – Struktura okvirov, kodiranje kanalov in
modulacija za digitalno prizemno televizijo (DVB-T)
Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for
digital terrestrial television
Ta slovenski standard je istoveten z: EN 300 744 Version 1.2.1
ICS:
33.170 Televizijska in radijska Television and radio
difuzija broadcasting
SIST EN 300 744 V1.2.1:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 300 744 V1.2.1:2005

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SIST EN 300 744 V1.2.1:2005
ETSI EN 300 744 V1.2.1 (1999-07)
European Standard (Telecommunications series)
Digital Video Broadcasting (DVB);
Framing structure, channel coding and modulation for
digital terrestrial television
European Broadcasting Union Union Européenne de Radio-Télévision
EBU
UER

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SIST EN 300 744 V1.2.1:2005
2 ETSI EN 300 744 V1.2.1 (1999-07)
Reference
REN/JTC-DVB-87 (6w000ioo.PDF)
Keywords
DVB, digital, video, broadcasting, terrestrial,
MPEG, TV, audio, data
ETSI
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Copyright Notification
No part may be reproduced except as authorized by written permission.
The copyright and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1999.
© European Broadcasting Union 1999.
All rights reserved.
ETSI

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SIST EN 300 744 V1.2.1:2005
3 ETSI EN 300 744 V1.2.1 (1999-07)
Contents
Intellectual Property Rights . 5
Foreword. 5
1 Scope. 6
2 References . 6
3 Definition, symbols and abbreviations . 6
3.1 Definition. 6
3.2 Symbols . 7
3.3 Abbreviations. 8
4 Baseline system . 8
4.1 General considerations. 8
4.2 Interfacing. 10
4.3 Channel coding and modulation. 10
4.3.1 Transport multiplex adaptation and randomization for energy dispersal . 10
4.3.2 Outer coding and outer interleaving. 11
4.3.3 Inner coding . 13
4.3.4 Inner interleaving . 14
4.3.4.1 Bit-wise interleaving. 14
4.3.4.2 Symbol interleaver. 18
4.3.5 Signal constellations and mapping . 20
4.4 OFDM frame structure. 24
4.5 Reference signals . 26
4.5.1 Functions and derivation . 26
4.5.2 Definition of reference sequence. 26
4.5.3 Location of scattered pilot cells . 27
4.5.4 Location of continual pilot carriers . 28
4.5.5 Amplitudes of all reference information. 28
4.6 Transmission Parameter Signalling (TPS) . 29
4.6.1 Scope of the TPS. 29
4.6.2 TPS transmission format . 30
4.6.2.1 Initialization. 30
4.6.2.2 Synchronization. 30
4.6.2.3 TPS length indicator. 30
4.6.2.4 Frame number. 31
4.6.2.5 Constellation. 31
4.6.2.6 Hierarchy information . 31
4.6.2.7 Code rates. 31
4.6.2.8 Guard Intervals . 32
4.6.2.9 Transmission mode. 32
4.6.2.10 Error protection of TPS . 32
4.6.3 TPS modulation. 33
4.7 Number of RS-packets per OFDM super-frame . 33
4.8 Spectrum characteristics and spectrum mask. 34
4.8.1 Spectrum characteristics. 34
4.8.2 Out-of-band spectrum mask (for 8 MHz channels) . 35
4.8.3 Centre frequency of RF signal (for 8 MHz UHF channels). 38
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SIST EN 300 744 V1.2.1:2005
4 ETSI EN 300 744 V1.2.1 (1999-07)
Annex A (informative): Simulated system performance for 8 MHz channels. 39
Annex B (informative): Definition of P and F . 41
1 1
Annex C (informative): Interleaving example. 43
Annex D (informative): Guidelines to implementation of the emitted signal . 44
D.1 Use of the FFT. 44
D.2 Choice of "baseband" centre frequency. 45
D.3 Other potential difficulties. 45
Annex E (normative): Values for 6 MHz and 7 MHz channels . 46
History. 49
ETSI

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SIST EN 300 744 V1.2.1:2005
5 ETSI EN 300 744 V1.2.1 (1999-07)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect
of ETSI standards", which is available free of charge from the ETSI Secretariat. Latest updates are available on the
ETSI Web server (http://www.etsi.org/ipr).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in SR 000 314 (or the updates on the ETSI Web server)
which are, or may be, or may become, essential to the present document.
Foreword
This European Standard (Telecommunications series) has been produced by the Joint Technical Committee (JTC)
Broadcast of the European Broadcasting Union (EBU), Comité Européen de Normalisation ELECtrotechnique
(CENELEC) and the European Telecommunications Standards Institute (ETSI).
NOTE: The EBU/ETSI JTC Broadcast was established in 1990 to co-ordinate the drafting of standards in the
specific field of broadcasting and related fields. Since 1995 the JTC Broadcast became a tripartite body
by including in the Memorandum of Understanding also CENELEC, which is responsible for the
standardization of radio and television receivers. The EBU is a professional association of broadcasting
organizations whose work includes the co-ordination of its members' activities in the technical, legal,
programme-making and programme-exchange domains. The EBU has active members in about 60
countries in the European broadcasting area; its headquarters is in Geneva.
European Broadcasting Union
CH-1218 GRAND SACONNEX (Geneva)
Switzerland
Tel: [phone]
Fax: [phone]
Digital Video Broadcasting (DVB) Project
Founded in September 1993, the DVB Project is a market-led consortium of public and private sector organizations in
the television industry. Its aim is to establish the framework for the introduction of MPEG-2 based digital television
services. Now comprising over 200 organizations from more than 25 countries around the world, DVB fosters
market-led systems, which meet the real needs, and economic circumstances, of the consumer electronics and the
broadcast industry.
National transposition dates
Date of adoption of this EN: 11 June 1999
Date of latest announcement of this EN (doa): 30 September 1999
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 31 March 2000
Date of withdrawal of any conflicting National Standard (dow): 31 March 2000
ETSI

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SIST EN 300 744 V1.2.1:2005
6 ETSI EN 300 744 V1.2.1 (1999-07)
1 Scope
The present document describes a baseline transmission system for digital terrestrial TeleVision (TV) broadcasting. It
specifies the channel coding/modulation system intended for digital multi-programme LDTV/SDTV/EDTV/HDTV
terrestrial services.
The scope is as follows:
- it gives a general description of the Baseline System for digital terrestrial TV;
- it identifies the global performance requirements and features of the Baseline System, in order to meet the service
quality targets;
- it specifies the digitally modulated signal in order to allow compatibility between pieces of equipment developed
by different manufacturers. This is achieved by describing in detail the signal processing at the modulator side,
while the processing at the receiver side is left open to different implementation solutions.
However, it is necessary in this text to refer to certain aspects of reception.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
• References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies.
•
A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same
number.
[1] ISO/IEC 13818: "Information technology - Generic coding of moving pictures and associated
audio information - Part 1 (Systems), 2 (Video), 3 (Audio)".
[2] EN 300 421: "Digital Video Broadcasting (DVB); Framing structure, channel coding and
modulation for 11/12 GHz satellite services".
[3] EN 300 429: "Digital Video Broadcasting (DVB); Framing structure, channel coding and
modulation for cable systems".
3 Definition, symbols and abbreviations
3.1 Definition
For the purposes of the present document, the following definition applies:
constraint length: number of delay elements +1 in the convolutional coder
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3.2 Symbols
For the purposes of the present document, the following symbols apply:
A(e) output vector from inner bit interleaver e
a bit number w of inner bit interleaver output stream e
e,w
aconstellation ratio which determines the QAM constellation for the modulation for hierarchical
transmission
B(e) input vector to inner bit interleaver e
b bit number w of inner bit interleaver input steam e
e,w
b output bit number do of demultiplexed bit stream number e of the inner interleaver demultiplexer
e,do
c complex cell for frame m in OFDM symbol l at carrier k
m,l,k
C' Complex modulation for a reference signal at carrier k
k
C' , Complex modulation for a TPS signal at carrier k in symbol l
l k
C/N Carrier-to-noise ratio
Dtime duration of the guard interval
d convolutional code free distance
free
f centre frequency of the emitted signal
c
G , G convolutional code Generator polynomials
1 2
g(x) Reed-Solomon code generator polynomial
h(x) BCH code generator polynomial
H(q) inner symbol interleaver permutation
H (w) inner bit interleaver permutation
e
i priority stream index
I Interleaving depth of the outer convolutional interleaver
I0,I1,I2,I3,I4,I5 inner Interleavers
j branch index of the outer interleaver
k carrier number index in each OFDM symbol
K number of active carriers in the OFDM symbol
K , K carrier number of the lower and largest active carrier respectively in the OFDM signal
min max
l OFDM symbol number index in an OFDM frame
m OFDM frame number index
m' OFDM super-frame number index
M convolutional interleaver branch depth for j = 1, M = N/I
n transport stream sync byte number
N length of error protected packet in bytes
N inner symbol interleaver block size
max
p scattered pilot insertion index
p(x) RS code field generator polynomial
P (f) Power spectral density for carrier k
k
P(n) interleaving Pattern of the inner symbol interleaver
r code rate for priority level i
i
s TPS bit index
i
t number of bytes which can be corrected by the Reed-Solomon decoder
T elementary Time period
T duration of an OFDM symbol
S
T Time duration of a frame
F
T Time duration of the useful (orthogonal) part of a symbol, without the guard interval
U
u bit numbering index
v number of bits per modulation symbol
w value of reference PRBS sequence applicable to carrier k
k
x input bit number di to the inner interleaver demultiplexer
di
x' high priority input bit number di to the inner interleaver demultiplexer
di
x" low priority input bit number di to the inner interleaver demultiplexer
di
Y output vector from inner symbol interleaver
Y' intermediate vector of inner symbol interleaver
y bit number q of output from inner symbol interleaver
q
y' bit number q of intermediate vector of inner symbol interleaver
q
z complex modulation symbol
ETSI

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SIST EN 300 744 V1.2.1:2005
8 ETSI EN 300 744 V1.2.1 (1999-07)
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ACI Adjacent Channel Interference
AFC Automatic Frequency Control
BCH Bose - Chaudhuri - Hocquenghem code
BER Bit Error Ratio
D/A Digital-to-Analogue converter
DBPSK Differential Binary Phase Shift Keying
DFT Discrete Fourier Transform
DVB Digital Video Broadcasting
DVB-T DVB-Terrestrial
EDTV Enhanced Definition TeleVision
FEC Forward Error Correction
FFT Fast Fourier Transform
FIFO First-In, First-Out shift register
HDTV High Definition TeleVision
HEX HEXadecimal notation
HP High Priority bit stream
IF Intermediate Frequency
IFFT Inverse Fast Fourier Transform
LDTV Limited Definition TeleVision
LO Local Oscillator
LP Low Priority bit stream
LSB Least Significant Bit
MPEG Moving Picture Experts Group
MSB Most Significant Bit
MUX MUltipleX
NICAM Near-Instantaneous Companded Audio Multiplex
OCT OCTal notation
OFDM Orthogonal Frequency Division Multiplexing
PAL Phase Alternating Line
PCR Program Clock Reference
PID Program IDentifier
PRBS Pseudo-Random Binary Sequence
QAM Quadrature Amplitude Modulation
QEF Quasi Error Free
QPSK Quaternary Phase Shift Keying
RF Radio Frequency
RS Reed-Solomon
SDTV Standard Definition TeleVision
SECAM Système Sequentiel Couleur A Mémoire
SFN Single Frequency Network
TPS Transmission Parameter Signalling
TV TeleVision
UHF Ultra-High Frequency
VHF Very-High Frequency
4 Baseline system
4.1 General considerations
The system is defined as the functional block of equipment performing the adaptation of the baseband TV signals from
the output of the MPEG-2 transport multiplexer, to the terrestrial channel characteristics. The following processes shall
be applied to the data stream (see figure 1):
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- transport multiplex adaptation and randomization for energy dispersal;
- outer coding (i.e. Reed-Solomon code);
- outer interleaving (i.e. convolutional interleaving);
- inner coding (i.e. punctured convolutional code);
- inner interleaving;
- mapping and modulation;
- Orthogonal Frequency Division Multiplexing (OFDM) transmission.
The system is directly compatible with MPEG-2 coded TV signals ISO/IEC 13818 [1].
Since the system is being designed for digital terrestrial television services to operate within the existing VHF and UHF
(see note) spectrum allocation for analogue transmissions, it is required that the System provides sufficient protection
against high levels of Co-Channel Interference (CCI) and Adjacent-Channel Interference (ACI) emanating from existing
PAL/SECAM/NTSC services. It is also a requirement that the System allows the maximum spectrum efficiency when
used within the VHF and UHF bands; this requirement can be achieved by utilizing Single Frequency Network (SFN)
operation.
NOTE: The OFDM system in the present document is specified for 8 MHz, 7 MHz and 6 MHz channel spacing.
The basic specification is the same for the three bandwidths except for the parameter elementary period T,
which is unique for the respective bandwidths. From an implementation point of view the elementary
period T can normally be seen as the inverse of the nominal system clock rate. By adjusting the system
clock rate the bandwidth and bit rate are modified accordingly.
To achieve these requirements an OFDM system with concatenated error correcting coding is being specified.
To maximize commonality with the Satellite baseline specification (see EN 300 421 [2]) and Cable baseline
specifications (see EN 300 429 [3]) the outer coding and outer interleaving are common, and the inner coding is
common with the Satellite baseline specification. To allow optimal trade off between network topology and frequency
efficiency, a flexible guard interval is specified. This will enable the system to support different network configurations,
such as large area SFN and single transmitter, while keeping maximum frequency efficiency.
Two modes of operation are defined: a "2K mode" and an "8K mode". The "2K mode" is suitable for single transmitter
operation and for small SFN networks with limited transmitter distances. The "8K mode" can be used both for single
transmitter operation and for small and large SFN networks.
The system allows different levels of QAM modulation and different inner code rates to be used to trade bit rate versus
ruggedness. The system also allows two level hierarchical channel coding and modulation, including uniform and multi-
resolution constellation. In this case the functional block diagram of the system shall be expanded to include the
modules shown dashed in figure 1. The splitter separates the incoming transport stream into two independent MPEG
transport streams, referred to as the high-priority and the low-priority stream. These two bitstreams are mapped onto the
signal constellation by the Mapper and Modulator which therefore has a corresponding number of inputs.
To guarantee that the signals emitted by such hierarchical systems may be received by a simple receiver the hierarchical
nature is restricted to hierarchical channel coding and modulation without the use of hierarchical source coding.
A programme service can thus be "simulcast" as a low-bit-rate, rugged version and another version of higher bit rate and
lesser ruggedness. Alternatively, entirely different programmes can be transmitted on the separate streams with different
ruggedness. In either case, the receiver requires only one set of the inverse elements: inner de-interleaver, inner decoder,
outer de-interleaver, outer decoder and multiplex adaptation. The only additional requirement thus placed on the
receiver is the ability for the demodulator/de-mapper to produce one stream selected from those mapped at the sending
end.
The price for this receiver economy is that reception can not switch from one layer to another (e.g. to select the more
rugged layer in the event of reception becoming degraded) while continuously decoding and presenting pictures and
sound. A pause is necessary (e.g. video freeze frame for approximately 0,5 seconds, audio interruption for
approximately 0,2 seconds) while the inner decoder and the various source decoders are suitably reconfigured and
reacquire lock.
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SIST EN 300 744 V1.2.1:2005
10 ETSI EN 300 744 V1.2.1 (1999-07)
Figure 1: Functional block diagram of the System
4.2 Interfacing
The Baseline System as defined in the present document is delimited by the following interfaces:
Table 1: Interfaces for the Baseline System
Location Interface Interface type Connection
Transmit Station Input MPEG-2 transport stream(s) multiplex from MPEG-2 multiplexer
Output RF signal to aerial
Receive Installation Input RF from aerial
Output MPEG-2 transport stream multiplex to MPEG-2 demultiplexer
4.3 Channel coding and modulation
4.3.1 Transport multiplex adaptation and randomization for energy
dispersal
The System input stream shall be organized in fixed length packets (see figure 3), following the MPEG-2 transport
multiplexer. The total packet length of the MPEG-2 transport multiplex (MUX) packet is 188 bytes.
This includes 1 sync-word byte (i.e. 47 ). The processing order at the transmitting side shall always start from the
HEX
MSB (i.e. "0") of the sync-word byte (i.e. 01 000 111). In order to ensure adequate binary transitions, the data of the
input MPEG-2 multiplex shall be randomized in accordance with the configurations depicted in figure 2.
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11 ETSI EN 300 744 V1.2.1 (1999-07)
Figure 2: Scrambler/descrambler schematic diagram
The polynomial for the Pseudo Random Binary Sequence (PRBS) generator shall be (see note):
14 15
1 + X + X
NOTE: The polynomial description given here is in the form taken from the Satellite baseline specification
EN 300 421 [2]. Elsewhere, in both the Satellite baseline specification and in the present document, a
different polynomial notation is used which conforms with the standard textbook of Peterson and Weldon
(Error correcting codes, second edition, MIT Press, 1972).
Loading of the sequence "100101010000000" into the PRBS registers, as indicated in figure 2, shall be initiated at the
start of every eight transport packets. To provide an initialization signal for the descrambler, the MPEG-2 sync byte of
the first transport packet in a group of eight packets is bit-wise inverted from 47 (SYNC) to B8 (SYNC).
HEX HEX
This process is referred to as "transport multiplex adaptation" (see figure 3b).
The first bit at the output of the PRBS generator shall be applied to the first bit (i.e. MSB) of the first byte following the
inverted MPEG-2 sync byte (i.e. B8 ). To aid other synchronization functions, during the MPEG-2 sync bytes of the
HEX
subsequent 7 transport packets, the PRBS generation shall continue, but its output shall be disabled, leaving these bytes
unrandomized. Thus, the period of the PRBS sequence shall be 1 503 bytes.
The randomization process shall be active also when the modulator input bit-stream is non-existent, or when it is
non-compliant with the MPEG-2 transport stream format (i.e. 1 sync byte + 187 packet bytes).
4.3.2 Outer coding and outer interleaving
The outer coding and interleaving shall be performed on the input packet structure (see figure 3a).
Reed-Solomon RS (204,188, t = 8) shortened code (see note 1), derived from the original systematic RS (255,239, t = 8)
code, shall be applied to each randomized transport packet (188 byte) of figure 3b to generate an error protected packet
(see figure 3c). Reed-Solomon coding shall also be applied to the packet sync byte, either non-inverted (i.e. 47 ) or
HEX
inverted (i.e. B8 ).
HEX
NOTE 1: The Reed-Solomon code has length 204 bytes, dimension 188 bytes and allows to correct up to 8 random
erroneous bytes in a received word of 204 bytes.
0 1 2 15
Code Generator Polynomial: g(x) = (x+l)(x+l)(x+l).(x+l), where l = 02
HEX
8 4 3 2
Field Generator Polynomial: p(x) = x + x + x + x + 1
The shortened Reed-Solomon code may be implemented by adding 51 bytes, all set to zero, before the information bytes
at the input of an RS (255,239, t = 8) encoder. After the RS coding procedure these null bytes shall be discarded, leading
to a RS code word of N = 204 bytes.
Following the conceptual scheme of figure 4, convolutional byte-wise interleaving with depth I = 12 shall be applied to
the error protected packets (see figure 3c). This results in the interleaved data structure (see figure 3d).
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The convolutional interleaving process shall be based on the Forney approach which is compatible with the Ramsey type
III approach, with I = 12. The interleaved data bytes shall be composed of error protected packets and shall be delimited
by inverted or non-inverted MPEG-2 sync bytes (preserving the periodicity of 204 bytes).
The interleaver may be composed of I = 12 branches, cyclically connected to the input byte-stream by the input switch.
Each branch j shall be a First-In, First-Out (F
...