Glossary

Audio compression scheme defined by MPEG-4. Used in conjunction with H.264 video encoding for DVB-H transmission.

Generally described as DVB-ASI (norm reference: ETSI TR 101 891). ASI defines the transport data format for carrying MPEG2-TS video streams. Electrical signaling levels are 800mV p-p.

Supplies the characteristics of a bouquet and the list of services.

BER is an indicator about the quality of the transmission. This is the ratio of the number of errorneous bits as regards to the the number of bits transmitted. Depending on the channel in use (satellite, terrestrial, mobile, cable transmittion), the BER is different. For DVB-T, the well-known quasi-error-free channel is attained with a BER of 10^-11, which implies an input BER of 2.10^-4 for the RS code.

CAT specifies the CA used and contains PIDs for Entitlement Management Message. These EMMs (generated by Conditional Access Provider) define authorization level (user rights) for conditional access systems. CAT is carried with PID = 1.

Contrary to satellite and cable, terrestrial broadcasting is characterized by high levels of multipath propagation (resulting in fading impairments). COFDM is particularly well-suited to cope with such interferences. FDM consists in dividing the available spectrum into many suchannels. Data is modulated onto a large number of carriers. The orthogonality of these carriers will ensure the receiver to retrieve carriers indepedently from each other. The term "coded" means error coding, interleaving and channel state information are used. DAB, T-DMB, DVB-T and DVB-H use COFDM modulation. In DVB-T, 2k and 8k mode referred to the number of carriers used. DVB-H added 4k mode.

Digital Audio Broadcasting standardized and developed by European project EUREKA 147.

Delta-t is located within MPE header and is intended for burst synchronization. DVB-H makes use of time-slicing for power consumption issue, which means no PCR information can be used (transmission interruption). Delta-t is one relative value that signals the next burst arrival time for the service under consideration. Delta-t is different for each MPE section. In one burst, we thus have as many delta-t value than MPE sections.

Chinese terrestrial digital television broadcasting developed by Tsinghua University of Beijing and Jiaotong University of Shanghai. This standard is to cover both fixed and mobile terminals.

European digital cable transmission defined in ETSI EN 300 429 v1.2.1. DVB-C uses QAM modulation and is adopted all over the world (China, Europe, Japan, US etc...).

Open DVB standard that enable Audio/Video services to be delivered to and through the home via Internet Protocol networking.

ECMs contain scrambled CW (control Word) for decrypting the transmitted program. That CW is first used by the encoder to scramble the programs. In DVB-H, CW is inserted in ECMs and sent encrypted along with the corresponding service. CW is frequently changed, the period is called crypto-period, and is most of the time equal to 10s.

EIT supplies the lists of events corresponding to a single service, and the characteristics of each of these events.

EMMs is an encrypted message that contains authorizations for the end-user wether it can or not acquire and view services as cable or satellite. The rights are sent for all the users, SIM based filtering is performed.

Transport interface specifications for DAB/T-DMB braodcasting. ETI is defined in ETS 300 799.

EVM is a measurement parameter for evaluating the quality of a modulation. It is especially used for quantifying the performance of a phase-shift modulation radio transmitter.

GOP is made of group of pictures betwenn two GOP headers. The first picture after a GOP header is an intra picture (also referred to as I-frame). This I-frame does not require any reference to other frame to be decoded. Following pictures are B-frames, and decoding process is based on previous one. GOP length if often referred to as the period by which an I-frame occurs.

GPS provides one very accurate clock reference for broadcast, especially for SFN networks. No localization information are used for SFN networks, only 1PPS and 10 MHz for both temporal and frequency synchronization.

Video compression defined in MPEG-4 part 10. DVB chose this video encoding type for DVB-H broadcasting.

Communication protocol used to manage the membership of Internet Protocol multicast groups. IGMP is used by IP hosts and adjacent multicast routers to establish multicast group memberships.

INT is a new SI table defined by DVB for DVB-H transmission. INT signals the availability of IP streams : it lists all multicast addresses in use, and corresponding DVB-H time slice/bursts characteristics. One burst may contain one or more multicast (IP) stream.

LDPC is a FEC code that allows data rate transmission close to theoretical maximum. Even if LDPC (as other FEC codes) does not guarantee perfect transmission, the probability of lost information can be made small. LDPC is the FEC core in DVB-S2 and DMB-TH.

Serial Parallel Interface that enables digital transmission information based on a voltage difference. The voltage difference is about 350 mVolts. The advantage of LVDS is to run at very high speed and accross cheap cables.

MER is defined by ETR 290 as a "figure of merit" of the modulated signal. For each symbol received, MER is calculated based on the ideal position within the constellation, and the one received. The closer the symbol is from the ideal position, the greater is the MER.

MFN is a broadcast network where all the transmitters transmit on different frequencies.

The aim of MIP packets is to set up SFN network. In SFN network, all the transmitter transmit at the same time. In order to synchronize the transmission, MIP table (PID=0x15) are inserted each megaframe. This MIP table contains information about the modulation/transmission parameters, and synchronization. addional optional data can be added to MIP packet for individual transmitter addressing. This process is performed by a MIP inserter (ENENSYS: NN6-MIP Inserter).

DSM-CC MPE is used in DVB-H for carrying IP data in MPEG-2 sections (TS packets). For this purpose, one section called datagram_section has been defined by DSM-CC, which extends DSM-CC private section format scope, enabling receiver filtering based on MAC addresses. Exactly one UDP datagram is embedded within one MPE section. Within MPE header, 6 bytes are allocated for MAC addresses, 2 of them are stored early in the datagram_section, which enables hardware filtering. Since 2 bytes are sufficient for MAC address, the following 4 bytes are used in DVB-H for storing delta-t synchronization information.

DVB-H improved FEC with longer interleaver (in-depth interleaving), but also introduced MPE-FEC correction, which makes DVB-H transmission more robust. MPE-FEC is a RS code based on the Application Data Table (ADT). Within ADT, IP datagrams are stored in columns, and RS code performed in line, hence additional natural interleaving.

Packetization defined in system norm ISO 13818 by MPEG-2. This packetization proved to be particularly efficient for services multiplexing and Audio/video synchronization. Packet size is fixed (188 bytes, 204 bytes if RS FEC), with variable size header. Payload can be either A/V, user-data or PSI/SI table.

Supplies network characteristics (identifier, name, link data etc...) and the lists of channels with characteristics such as broadcasting type, parameters (frequency, modulation parameters ...) etc... DVB-H broadcasting is most of the time signaled within the NIT (the other way is to signal DVB-H broadcasting within the BAT).

Combination of hardware and software used to monitor and administer a network.

See COFDM.

PCR information is carried in TS header (48 bits located in field adapation_field). This information enables clock synchronization of the encoder as regards to the decoder. In MPEG-2, video source is clocked at 27 MHz. Based on PCR sent by the encoder, the decoder regenerates the system clock (27MHz), by adjusting (either reset, slow down or speed up) its own STC (System Clock Time).

PMT lists all the PIDs (all TS packets) containing elements of a particular program (audio, video, data, and Program Clock Reference (PCR)). PMT's PID are specified by the PAT table.

MPEG-2 TS header 13 bits field used to identify uniquely the audio, video components and other data (like PSI/SI tables) for a particular service within one Transport Stream.

Recommendations for the transmission of professional MPEG-2 TS data over IP networks. Those recommendations cover the following points : transmission protocol, forward error correction (FEC) scheme (video-specific packet-based algorithm), timing, recovery, jitter tolerance and latency issues

Set of MPEG-2 data defined in ISO 13-818. These PSI tables provide means for retrieving the information for one particular program within the transport stream (TS). For that concern, MPEG-2 defined a certain number of tables :

QPSK can be seen as a special case of QAM where the amplitude of the modulating signal is constant (only the phase is varying).

RST indicates a change of status of one or more events without having to retransmit the corresponding EIT. RST is carried with PID = 0x13.

RTP protocol is defined in RFC 3550 and is built on top of User Datagram Protocol (UDP). RTP protocol is used to transmit services with real-time constraints (audio, video...). RTP enables:

Applications using RTP are very sensitive to delay (and very robust against packet loss). UDP is thus prefered to TCP for such applications.

SAP is a protocol used to announce multicast session. SAP packets are multicast periodically to a well-known multicast address, with port=9875. SAP payload is an SDP description, that will provide means for getting access to the session (multicast address, type of A/V encoding, ports used...). In DVB-H, SAP announcement are multicast by the H.264 encoder.

Supplies the list of services present within a given channel and the characteristics of each of these services. SDT is carried with PID = 0x11.

Network topology where all transmitters broadcast over the same frequency, the same OFDM symbols and at the same time. As digital services are evolving and various (terrestrial, mobile), there is a strong constraint to optimize bandwidth/spectrum. SFN is the solution: SFN build up is achieved using one Single Frequency Network Adapter (NN6-MIP^TM) that will insert MIP packet into TS stream. Synchronization between NN6-MIP^TM and modulators is achieved by means 1PPS and 10 MHz derived from GPS.

SNMP is used by network management systems to monitor network-attached devices for conditions that warrant administrative attention.

ST enables the replacement of complete tables due for invalidation.

Supplies the time reference in terms of UTC time/date, enabling joint management services events. ESG data processing and display depends on information provided by TDT (display of today, tomorrow, next week programs etc...).

In DVB-H, time-slicing consists of transmitting chunks of data in bursts, which alllows the receiver to be on only during a small period of time. The idea behind is clearly to reduce handset battery consumption for mobile reception. The target is 90% power saving. Between slice (off-time period), handset can monitor neighborhood for seamless handover.

UDP is one of the core protocols of the Internet Protocol suite. UDP datagram is encapsulated into one IP packet. UDP does not provide any means for reliability (order is not guaranteed, lost packets cannot be retrieved), but its advantage is fast content delivery, transmission simplicity, and a checksum to ensure content correctness. UDP header consists of one source port (16 bits), one destination port (16 bits), UDP datagram length (16 bits) and one 16-bits checksum.

Radio frequency range, from 300 MHz to 3 GHz.

UTC is a high precision atomic time standard, often referred to as Greenwich Time when it comes to describe time zones. Each time zone is expressed as a positive or negative offset from UTC.

Radio frequency range, from 30 MHz to 300 MHz.