Glossary
| A | B | C | D | E | F | H | I | J | L | M | N | O | P | R | S | T | U | V | W | X |
A
AAC
Advanced Audio CodingHE-AAC v2, a version of AAC, is used for both DAB+ and DMB.
AAC+
Used as a synonym for HE-AAC v2
aacPlus
Used as a synonym for HE-AAC v2
AIC
Auxiliary Information ChannelPart of the Main Service Channel (MSC) used to carry data which cannot be accommodated in the Fast Information Channel (FIC).
ASF
Advanced Systems Format
Advanced Systems Format (formerly Advanced Streaming Format, Active Streaming Format) is Microsoft's proprietary digital audio/digital video container format, especially meant for streaming media.
ASF Specification
B
Band III
Frequency band between 174 and 230 MHz of the VHF range, used for DAB services (formerly used for analogue television).
BIFS
Binary Format for ScenesScene description language of MPEG-4, designed for representing, delivering and rendering interactive and streamable rich-media services (including audio, video, 2D & 3D graphics).
BSAC
Bit Sliced Arithmetic CodingPart of the MPEG-4 standard (ISO/IEC 14496-3 subpart 4) for scalable audio coding. It uses a noiseless coding alternative to AAC, with the rest of the processing being identical to AAC. BSAC is one of the two audio codecs used for DMB, the other is HE-AAC v2.
BWS
Broadcast WebsiteAllows a service provider to deliver HTML content via DAB without the need for a return channel.
C
CA
Conditional AccessMechanism by which the user access to service components can be restricted.
CIF
Common Interleaved Framesserial digital output from the main service multiplexer which is contained in the Main Service Channel part of the transmission frame.
COFDM
Coded Orthogonal Frequency Division MultiplexSynonym: OFDM
Modulation method (division into small units, chronological nesting, transmission on various carrier frequencies). COFDM is used in DAB, DAB+ and DMB.
Convolutional Coding
Coding procedure which generates redundancy in the transmitted data stream in order to provide ruggedness against transmission distortions.
CRC
Cyclic Redundancy CheckA type of function that takes as input a data stream of any length and produces as output a value of a certain fixed size. Can be used as a checksum to detect accidental alteration of data during transmission or storage.
CU
Capacity UnitSmallest addressable unit of the Common Interleaved Frames (CIF), comprising of 64 bits. The CIF contains 864 CUs, and the MSC is made up of 1 to 4 CIFs, depending on the Transmission Mode.
D
DAB
Digital Audio BroadcastingMethod for the digital transmission of radio signals for mobile reception, developed by EUREKA project 147.
DAB+
Additional audio codec for 'Digital Audio Broadcasting', based on the new audio coding technology HE-AAC v2 (also known as AAC+ or MPEG-4). DAB+ is backwards compatible to the current DAB standard. DAB, DAB+ and DMB are all part of the Eureka-147 family of standards.
DAB+ upgradeable
A DAB receiver is called DAB+ upgradeable if it can be upgraded via USB to a DAB+ receiver.
DLS
Dynamic Label SegmentSupplementary data services in text form (up to 128 characters) running alongside the DAB or DAB+ radio programme. Similar to RDS on FM radio.
DMB
Digital Multimedia BroadcastingSynonym: T-DMB
Method for the digital transmission of multimedia signals (especially video services) for mobile reception. DMB is part of the same family of standards as DAB and DAB+.
DQPSK
Differential Quadrature Phase-Shift KeyingDigital phase modulation scheme that conveys data by changing or modulating the phase of the carrier wave. DQPSK is used in DAB, DAB+ and DMB.
DRC
Dynamic Range ControlWith help of the Dynamic Range Control (DRC) the receiver may reduce the dynamic range of the audio signal. The purpose of this is to adapt the dynamic range of the audio signal to listening in a noisy environment.
DRM
Digital Radio Mondiale
Method for the digital transmission of VHF radio signals (AM), deleloped by the DRM consortium.
Official Website
E
Ensemble
Entity of programme and data
services (usually about 9 to 12 DAB programmes or about 18 to 32 DAB+ programmes) with a fixed total capacity which is processed and transmitted.
The DAB multiplex data stream has a maximum capacity of 2.25 Mbit/s, normally shared by a number of services (radio / data). The name multiplex relates to the fact that the individual data streams are multiplexed (that is, they are transmitted alternately in chunks). A multiplex needs a bandwidth of about 1.5 MHz on the frequency band.
EPG
Electronic Programme GuideAn Electronic Programme Guide is an on-screen guide to scheduled radio or television programmes, allowing a viewer/listener to navigate, select, discover and record content by time, title, channel, genre, etc.
ES
Elementary StreamConsecutive flow of compressed mono-media data, i.e. one of the coded audio, coded video or other coded bitstreams.
ETSI
European Telecommunications Standards Institute
The European Telecommunications Standards Institute is an independent, non-profit, standardization organization of the telecommunications industry (equipment makers and network operators) in Europe, with worldwide projection.
Official Website
ETSI EN
ETSI European NormPart of ETSI document name, e.g. EN 300 401
ETSI TS
ETSI Technical SpecificationPart of ETSI document name, e.g. ETSI TS 102 428
EUREKA
Initiative for application-oriented research in Europe: framework for cross-border cooperative ventures in the fields of industry and science.
F
F-PAD
Fixed Programme Associated DataPart of the capacity allocated for supplementary programme data (see article on PAD). Two bytes at the end of each DAB audio frame are reserved for F-PAD.
FEC
Forward Error CorrectionForward Error Correction, in the form of Reed-Solomon (RS) outer error protection and outer interleaving, can be applied to sub-channels carrying service components in packet mode in order to further increase the error robustness of DAB data delivery.
FIB
Fast Information BlockThe FIB contains 256 bits and comprises an FIB data field and a CRC. The FIB data field consists of one or more Fast Information Group (FIG).
FIC
Fast Information ChannelThe FIC is a non-time-interleaved data channel with fixed equal error protection. In particular it is used to send the DAB Multiplex Configuration Information (MCI) and optionally Service Information and data services.
FIG
Fast Information GroupThe FIG carries the following parts: Multiplex Configuration Information (MCI), Service Information (SI), FIC Data Channel (FIDC) and Conditional Access (CA).
H
H.264
Synonym for MPEG-4 Part 10
HE-AAC v2
High Efficiency Advanced Audio Coding version 2Synonyms: AAC+, MP4, MPEG-4, aacPlus
High Efficiency AAC (HE-AAC) is a lossy data compression scheme for digital audio. It is an extension of Low Complexity AAC (AAC LC) optimized for low-bitrate applications such as streaming audio. HE-AAC version 1 (HE-AAC v1) uses Spectral Band Replication (SBR) to enhance the compression efficiency in the frequency domain. HE-AAC version 2 (HE-AAC v2) couples SBR with Parametric Stereo (PS) to enhance the compression efficiency of stereo signals.
I
ITU
International Telecommunication Union
ITU is the United Nations agency for information and communication technologies.
Official Website
J
Joint Stereo
Audio mode in which two channels forming a stereo pair (left and right) are encoded within one bit stream and for which stereophonic irrelevance or redundancy is exploited for further bit reduction.
L
L Band
Frequency band between 1 and 2,6 GHz of the UHF range, used for local DAB/DMB services.
LSF
Low Sampling FrequencyLow bitrate encoding with halved sampling rate.
M
M/S
Music/Speech indicationA two-bit flag which indicates whether the transmitted sound consists of music or speech. The receiver may use this information to balance the loudness of different types of programme according to the listener taste.
MCI
Multiplex Configuration InformationThe MCI lists all services that are available in a DAB ensemble, and defines how they are organised into sub-channels and service components.
MOT
Multimedia Object TransferMOT (EN 301 234) is the transmission protocol used in DAB for transferring file oriented data in DAB audio or data channels. It is tailored to the needs of multimedia services and the specific constraints given by the broadcasting characteristics of the DAB system. It supports two different transport modes, MOT header mode and MOT directory mode.
MOT Directory
Multimedia Object Transfer DirectoryMOT Directory can be used if file system structures with multiple files are broadcast as a data carousel, like in the Broadcast Website (BWS) application.
MOT Header
Multimedia Object Transfer HeaderMOT header mode is used if there is just one MOT object valid at any time (e.g. in the Slide Show application, where a new slide is received, processed, displayed and discarded).
MP2
Used as a synonym for MPEG Audio Layer II
MP4
Used as a synonym for HE-AAC v2
MPEG Audio Layer II
Synonyms: MP2, MPEG-1 Layer II, MUSICAMMPEG Audio Layer II is an audio codec defined by ISO/IEC 11172-3. It is a dominant encoding standard for audio broadcasting as part of the DAB digital radio and DVB digital television standards, and it is the core of the better known MP3 standard.
MPEG-1 Layer II
Used as a synonym for MPEG Audio Layer II
MPEG-4
Used as a synonym for HE-AAC v2
MPEG-4 AVC
Used as a synonym for MPEG-4 Part 10
MPEG-4 Part 10
Synonyms: H.264, MPEG-4 AVCStandard for video compression used in DMB. The two standard documents for MPEG-4 AVC (ISO/IEC 14496-10) and H.264 (ITU-T H.264 standard) are jointly maintained so that they have identical technical content.
MSC
Main Service ChannelThe MSC is a time-interleaved data channel divided into a number of sub-channels which are individually convolutionally coded, with equal or unequal error protection. Each sub-channel may carry one or more service components. used to carry audio and data service components.
Multiplex
Output of a multiplexer (often used as a synonym for ensemble).
Multiplexer
Synonym: MUXMultiplexer: Device that performs multiplexing by selecting one of many analog or digital data sources and outputting that source into a single channel.
MUSICAM
Masking Pattern Adapted Universal Subband Integrated Coding And MultiplexingUsed as a synonym for MPEG Audio Layer II
MUX
Used as a synonym for Multiplexer
N
NPAD
Non Programme Associated DataData services not associated with a radio programme.
O
OFDM
Orthogonal Frequency-Division MultiplexingUsed as a synonym for COFDM
P
Packet Mode
Mode of data transmission in which data are carried in addressable blocks called packets. The packet structure supports multiplexing of various service components in one sub-channel; a sequence of packets is conveyed in a sub-channel.
PAD
Programme Associated DataData services provided as supplementary information to a radio programme, such as Dynamic Label Segment (DLS) and Multimedia Object Transfer (MOT). Each DAB audio frame contains a number of bytes specifically for carrying Programme Associated Data (PAD). At the end of the DAB audio frame, a capacity of at least two bytes, called Fixed Programme Associated Data (F-PAD), is provided, irrespective of the sampling frequency, bit rate or the audio mode (i.e. single channel, stereo and dual channel modes will all have the same capacity of F-PAD). But the broadcaster may choose to extend this capacity, called Extended Programme Associated Data (X-PAD) in order to transmit more audio related data.
PES
Packetized Elementary StreamPacketized audio, video or data elementary stream (ES) to be fed into the transport stream (TS) multiplexer.
Protection Level
Level specifying the degree of protection against transmission errors provided by convolution coding.
PS
Parametric StereoFeature used in HE-AAC v2 to further enhance efficiency in low bandwidth stereo media. It performs sparse coding in the spatial domain, somewhat similar to what SBR does in the frequency domain. An HE-AAC v2 bitstream is obtained by downmixing the stereo audio to mono at the encoder along with 2-3 kbit/s of side info (the Parametric Stereo information) in order to describe the spatial intensity stereo generation and ambience regeneration at the decoder. By having the Parametric Stereo side info along with the mono audio stream, the decoder (player) can regenerate a faithful spatial approximation of the original stereo panorama at very low bitrates.
PTy
Programme TypeFeature allowing programme contents to be categorized according to their intended audience.
R
RDS
Radio Data SystemTransmission of additional text data via FM broadcast.
RS
Reed-SolomonError-correcting code that works by oversampling a polynomial constructed from the data. The polynomial is evaluated at several points, and these values are sent or recorded. By sampling the polynomial more often than is necessary, the polynomial is over-determined. As long as "many" of the points are received correctly, the receiver can recover the original polynomial even in the presence of a "few" bad points. Reed-Solomon error correction is used in DAB+ and DMB.
S
SBR
Spectral Band ReplicationTechnology to enhance audio or speech codecs, especially at low bit rates and is based on harmonic redundancy in the frequency domain. SBR replicates higher frequency content by transposing up harmonics from the lower and mid-frequencies at the decoder.
Service Following
Synonym for Service Linking
Service Linking
Allows cross-referencing to other modes of reception of the same programme, such as FM, DRM, AM and other DAB ensembles. Receivers allowing this function will automatically switch to other modes of reception if the current one becomes unavailable (e.g. when leaving the coverage area). Synonym: Service Following
SFN
Single Frequency NetworkNetwork of DAB transmitters sharing the same radio frequency to achieve a large area coverage.
SI
Service InformationThe SI provides supplementary information about audio and data services, which is not included in the Multiplex Configuration Information (MCI). The Service Information (SI) features which may be carried in the FIC include the following: service component language, service linking, date and time, Programme Number, Programme Type (PTy), announcements, regional identification, other ensembles, FM and AM services information, frequency information, transmitter identification information, ensemble, service and service component labels, etc.
SL
Synchronization LayerProvides timing and synchronization information between elementary stream components in a transport stream (TS).
Stream Mode
Mode of data transmission allowing one service component per sub-channel to be transmitted transparently at a fixed bit rate.
Synchronization Channel
Used internally within the DAB transmission system for basic demodulator functions, such as transmission frame synchronization, automatic frequency control, channel state estimation, and transmitter identification.
T
T-DMB
Terrestrial Digital Multimedia BroadcastingUsed as a synonym for DMB
TMC
Traffic Message ChannelChannel for traffic information.
TPEG
Transport Protocol Experts GroupThe group of experts that developed a standard (of the same name) for transmitting traffic information via digital systems such as DAB and DVB.
Transmission Frame
Each transmission frame in the DAB transmission system combines three channels: Synchronization Channel, Fast Information Channel (FIC) and Main Service Channel (MSC).
Transmission Mode
There are 4 different transmission modes defined in DAB: Transmission mode I (intended for SFN in Bands I, II and III), transmission mode II (intended for local services in Bands I, II, III, IV, V and L-band), transmission mode III (intended for frequencies below 3 GHz and cable) and transmission mode IV (intended for local services in Bands I, II, III, IV, V and L-band).
TS
Transport StreamCommunications protocol for audio, video, and data. Allows multiplexing of digital video and audio and synchronisation of the output, and offers features for error correction for transportation over unreliable media.
U
UHF
Ultra high frequencyRange of electromagnetic waves whose frequency is between 300 MHz and 3 GHz (3,000 MHz). Also known as the decimeter band or decimeter wave as the wavelengths range from ten to one decimeters.
V
VHF
Very High FrequencyRadio frequency range from 30 MHz to 300 MHz, also known as the meter band or meter wave as the wavelengths range from ten to one meters.
W
World DMB Forum
Used as a synonym for WorldDMB
WorldDAB
Former name of WorldDMB
WorldDMB
Synonym: World DMB ForumThe WorldDMB Forum is an international non-governmental organisation whose objective is to promote, harmonise and co-ordinate the implementation of DAB Digital services based on the Eureka 147 DAB system. It is dedicated to encouraging international co-operation and co-ordination between sound and data broadcasters, network providers, manufacturers, governments and official bodies, thus gaining consensus for the smooth introduction of DAB based services.
X
X-PAD
eXtended Programme Associated DataPart of the capacity reserved for supplementary programme data (see article on PAD). X-PAD can be allocated dynamically at the end of each DAB audio frame.