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BROADCASTING DIVISION
APPLICATION NOTE
The most common abbreviations
used in the standards for digital TV:
MPEG2, DVB and ATSC
Products:
MPEG2 DTV RECORDER GENERATOR DVRG
MPEG2 MEASUREMENT GENERATOR DVG
MPEG2 REAL TIME MONITOR DVRM
MPEG2 MEASUREMENT DECODER DVMD
QAM TEST RECEIVER/DEMODULATOR EFA
TV TEST TRANSMITTER SFQ
7BM27_0E
The most common abbreviations used in the
standards for digital TV:
MPEG2, DVB and ATSC
The introduction of the transmission of compressed TV signals to MPEG2 and DVB for cable,
satellite and terrestrial (COFDM) lead to the creation of many abbreviations that have to be
explained to the "uninitiated". In the previous three lines, three abbreviations whose meanings are
not obvious have already been mentioned. A table explaining what these abbreviations mean is
therefore essential.
1 MPEG2 Abbreviations
DFD Displaced Frame Difference
Differential picture if there is
Adaptation Field
motion
Ancillary program data
(especially PCR) which are
DPCM Differential Pulse Code
uncoded and are transmitted
Modulation
at least every 100ms acc. to
MPEG2 or 40 ms acc. to DVB
specifications DTS Decoding Time Stamp
BAT Bouquet Association Table Stamp for decoding time, only
Table describing a bouquet of transmitted if not identical with
programs offered by a PTS; reference to PID
broadcaster
EIT Event Information Table
Block 8x8 pixel block, MPEG2 TV guide
coded
ES Elementary Stream
CA Conditional Access Compressed data stream for
Information of whether the video, audio or data.
program is scrambled Preliminary stage to
PES
CAT Conditional Access Table
GOP Group of Pictures
(PID=1):
Reference to scrambled
programs I, P, and B pictures
Intra-coded pictures (I),
CIF Common Intermediate predicted pictures (P) and bi-
directional prediction pictures (B)
Format
Picture format
IRD Integrated Receiver Decoder
Receiver with (MPEG)
CRC Cyclic Redundancy Check
decoder
MPEG Motion Picture Experts
DCT Discrete Cosine
Group
Transform
sometimes called Moving Picture
Experts Group
-1
DCT / IDCT Inverse Discrete Cosine
MUSICAM Masking Pattern Adapted
Transform
Universal Subband Integra-
ted Coding and Multiplexing
Compression method for
audio coding
2
BROADCASTING DIVISION
NIT Network Information Table PTS Presentation Time Stamp
Information about orbit, Time stamp for vision and
transponder etc. sound, transmitted at least
every 0.7 sec. Integrated into
PAT Program Association PES
Table (PID=0):
List of all the programs Q Quantization
contained in TS Multiplex
with reference to PID of PMT Q-1 Inverse quantization
Pay Load Useful data in TS QS Quantization scaling
PCM Pulse Code Modulation RLC Run Length Coding
Coding of data with different
PCR Program Clock Reference number of bits. Frequently
Reference in TS for the reoccurring data has the smallest
27-MHz clock recovery. number of bits, data seldom
Transmitted at least every reoccurring have the highest
0.1 sec number of bits.
PES Packetized Elementary RST Running Status Table
Stream Accurate and fast adaptation
Video and audio data packets to a new program run if time
and ancillary data of changes occur in the schedule
definable length
Section A table is subdivided into
PES Header Ancillary data for an several sections. If there is a
elementary stream change, only the section
affected is transmitted
PID Packet Identification
Identification of programs in SI Service Information
the transport stream All the data required by the
receiver to demultiplex and
PMT Program Map Table: decode the various
Reference to packets with programs in the TS
PCR
Name of programs, copyright, SIF Source Input Format
reference of the data streams
with PIDs etc. belonging to the SCR System Clock Reference
relevant program Reference in ES for synchro-
nizing the system demultiplex
Prediction Prediction of a picture (P or B) clock in the receiver,
with indication of a motion transmitted at least every
vector 0.7 sec. Integrated into PES
Profile Subdivision of video coding SDT Service Description Table
into different resolutions Description of programs
offered
PS Program Stream
Multiplex of several audio and STC System Time Clock
video PES using the same 27-MHz clock, regenerated
clock. from PCR for a jitter-free
PSI Program Specific Informa- readout of MPEG data
tion
Data transmitted in TS for the
demultiplexer in the receiver
(eg PAT, PMT, CAT)
3
BROADCASTING DIVISION
SYNC(_byte) Synchronization byte in TS UTC Universal Time, Co-
header value 0x47 ordinated
Greenwich meantime
TS Transport Stream
VBR Variable Bit Rate
TS Header The first 4 bytes of each TS
packet contain the data (PID) VLC Variable Length Coding
required for the demultiplexer Coding of data with
in addition to the sync byte variable number of bits (also
(0x47). These bytes are see RLC)
never scrambled.
ZigZag Scan Zigzag scan of
TDT Time and Date table quantized DCT coeffi-
UTC time and date cient matrix. This gives an
efficient run length coding
TOT Time Offset Table (RLC)
UTC time and date with
indication of local time offset
4
BROADCASTING DIVISION
2 DVB and ATSC Abbreviations DVB Digital Video Broadcasting
Broadcasting TV signals
ADSL Asymmetric digital subscrib- to a digital standard
er line
A COFDM-coded digital data DVB-C Digital Video Broadcasting-
stream with a rate up to Cable
8 Mbit/s (down stream) and Broadcasting TV signals
1 Mbit/s (up stream) is to a digital standard by cable
transmitted via telephone DVB-S Digital Video Broadcasting-
lines, mainly for video on Satellite
demand. Broadcasting TV signals
to digital standard
ATSC Advanced Television via satellite
Systems Committee
american standardization DVB-T Digital Video Broadcasting-
group for digital terrestrial Terrestrial
transmission Terrestrial broadcasting of TV
signals to digital standard
CNR Carrier to Noise Ratio
Indicates how far the noise Convolutional Coding
level is down on carrier level The data stream to be trans-
mitted via satellite and
COFDM Coded Orthogonal Frequen- terrestrial (DVB-S, DVB-T) is
cy Domain Multiplex loaded bit by bit into shift
Up to 6817 single carriers registers. The data which is
1.116 kHz apart are QAM- split and delayed as it is
modulated with up to 64 shifted through different
states. registers is combined in
"Coded" means that the data several paths. This means that
to be modulated has error double the data rate (2 paths)
control. is usually obtained. Puncturing
Orthogonality means that follows to reduce the data rate:
the spectra of the individual the time sequence of the bits
carriers do (almost) not is predefined by this coding
influence each other as a and is represented by the
spectral maximum always trellis diagram.
coincides with a spectrum zero
of the adjacent carriers. FEC Forward Error Correction
A single-frequency network Error control bits added to use-
is used for the actual ful data in the QAM/QPSK
transmission. modulator for DVB-C, -S and
DVB-T.
Constellation Diagram
Way of representing the I and Single-frequency network
Q components for QAM Transmitter network in which
or QPSK modulation. The all the transmitters use the
position of the points in the same frequency. The
constellation diagram coverage areas overlap.
provides information about Influece of echoes are
distortions in the QAM minimized by guard intervals.
or QPSK modulator as well as The transmitters are separated
about distortions after the by up to 60 km. The special
transmission of digitally coded feature of these networks is
signals. efficient frequency utilization
Guard interval additional safety margin
between two transmitted sym-
5
BROADCASTING DIVISION
bols in the COFDM standard. bits of a data stream are
The guard interval ensures transmitted with one symbol,
that echoes occurring in the depending on the QAM level
single-frequency network are (4, 16, 32, 64, 128, 256). This
eliminated until the received type of modulation is used in
symbol is processed. cable systems and for coding
the COFDM single carriers
Interleaver The RS-protected transport
packets are reshuffled byte by QEF Quasi Error Free
byte by the 12-channel Less than one uncorrected
interleaver. (RS FEC Reed error per hour at the input of
Solomon FEC) Due to this the MPEG2 decoder.
reshuffle what were (BER 10-11)
neighbouring bytes are now
separated by a maximum of QPSK
2244 bytes from other TS Quadrature Phase Shift
packets. The purpose of this is Keying
the burst error control for Type of modulation for digital
defective data blocks signals (DVB-S and -T). The
digital, serial signal
Mapping Conversion of bytes (8 bits) components I and Q directly
to 2n-bit wide symbols. control phase shift keying. The
n is thus the bit width for the I constellation diagram with its
and Q quantization; eg at four discrete states is obtained
64 QAM the symbol width is by representing the signal
2n = 6 bit, n = 3, ie components using the I and Q
I and Q are subdivided into signals as coordinate axes.
23 = 8 amplitude values each Due to the high nonlinear
distortion in the satellite
Puncturing Puncturing (DVB-S and -T) channel, this type of
follows to reduce the in- modulation is used for satellite
creased data rate after transmission: The 4 discrete
convolutional coding: Various states all have the same
registers are not used. The amplitude that is why non-
additional redundancy is used linear amplitude distortions
for error control. The two data have no effect.
streams after puncturing are
directly applied as I and Q RS Protection Code RS(204,188,8)
input signals to the QAM or (RS = Reed Solomon)
QPSK modulator after filtering 16-byte long error control code
to fulfil the first Nyquist added to every transport
criterion. packet consisting of 187
(scrambled) bytes +1 syncbyte
QAM Quadrature Amplitude with the following result:
Modulation The packet has a length of 204
Type of modulation for digital bytes and the decoder can
signals (DVB-C and -T). Two correct up to T = 8 errored
signal components I and Q are bytes. This code ensures a
each quantized and modulated residual Bit Error ratio BER of
onto two orthogonal carriers as approx. 1x10-11 at an input
-4
appropriate for the QAM level error ratio of 2x10 .
(4, 16, 32, 64, 128, 256). The
constellation diagram is
obtained by plotting the signal
components with I and Q as
the coordinate axes.
Therefore, 2, 4, 5, 6, 7 or 8
6
BROADCASTING DIVISION
SFN Single Frequency Network searched for through the trellis
diagram and incorrectly
transmitted bits are corrected.
Trellis Diagram
The time sequence of the bits n VSB Modulation
(DVB-S and -T) is predefined Transmission of n discrete
by convolutional coding and, amplitude values using the
like the state diagram of a vestigial sideband method
finite automaton, is on normal terrestrial (ATSC)
represented as a trellis channels and conventional IF
diagram. modulators. The most
common variant is 8-VSB
Viterbi Decoding transmission already tested in
Viterbi decoding makes the US. With 8 VSB, 3 bits
use of the predefined time (23 = 8) of the data stream are
sequence of the bits through transmitted per amplitude
convolutional coding (DVB-S value
and -T). Thanks to a series of
logic decisions, the most
probably correct way is
3. ATSC Tables and Protocols
PMT TS Program Map Table:
ATSC Advanced Television Reference to packets with
Systems Committee PCR
american standardization Name of programs, copyright,
group for digital terrestrial reference of the data streams
transmission with PIDs etc. belonging to the
relevant program
CAT Conditional Access Table Table ID 0x02
(PID=1):
Reference to scrambled PSIP Program and System
programs Information Protocol
Table ID 0x01
PTC Physical Transmission
CVCT Cable Virtual Channel Table Channel
Table ID 0xC9
RRT Rating Region Table
EIT Event Information Table Table ID 0xCA
Table ID 0xCB
SI Sytem Information
ETT Extended Text Table
Table ID 0xCC STT System Time Table
Table ID 0xCD
ETM Extended Text Message
TVCT Terrestrial Virtual Channel
MGT Master Giude Table Table, Table ID 0xC8
Table ID 0xC7
8 VSB Vestigial Side Band
PAT Program Association Modulation
Table (PID=0): digital terrestrial broadcast
List of all the programs mode
contained in TS Multiplex
with reference to PID of PMT 16 VSB Vestigial Side Band
Table ID 0x00 Modulation
PIT Program Identification Table High Data Rate mode
especially for Cable Systems
7
BROADCASTING DIVISION
4 The Digital TV System
The second area consists of transmission
The transmission of digitized vision and sound
levels DVB - C, DVB - S, DVB - T
together with different ancillary data is
At the transmitter end this comprises
subdivided into precisely defined areas.
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