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LENCO
TFT-711
ENGLISH
Multiplexer (Mux)
A physical device which is capable of inserting data into and extracting data from an MPEG-2
transport stream.
NorDig
A Scandinavian organization specifying a common platform for Digital Television to be used
within the Nordic region (Denmark, Finland, Iceland, Norway and Sweden). The NorDig test
specifications (NorDig Unified 1.0.2) are regarded as one of the most strict in the world and
are followed by many broadcasters, network operators and manufacturers of receivers.
On-Screen Display (OSD)
On screen display of menu for user’s setup of receiver’s operating parameters. Also refers to
display of choices and interaction with receiver and/or program.
Orthogonal Frequency
Division Multiplexing
(OFDM)
A modulation system which uses a very large number of separate radio frequency carriers
each of which carries a small proportion of the total information content to be sent. DVB based
digital television broadcasts use Coded OFDM.
Packet Identifier (PID)
A unique integer value used to identify elementary streams of a program in a single- or multi-
program MPEG-2 stream. Carried within each 4byte packet header (13 bits).
Phase Alternate Line (PAL)
An analog encoding system for color television. Compatible with analog monochrome systems
of the same scanning rates. It has a high frequency sub carrier to carry two color component
signals, similar to the principles used in NTSC but alternates the phase of one of the color
signals so that the receiver may correct color errors with a delay line.
Polarisation
Orientation of the wave transmitted by the transmitter. The majority of emissions are
horizontal, some are vertical.
Quadrature Amplitude
Modulation (QAM)
A method of modulating digital signals onto a radio-frequency carrier signal involving both
amplitude and phase coding.
Quadrature Phase-Shift
Keying (QPSK)
A method of modulating digital signals onto a radio-frequency carrier signal using four phase
states to code two digital bits.
Service multiplex and
transport
In an MPEG system, ‘service multiplex and transport’ refers to the division of the digital data
stream into ‘packets’ of information and the means of uniquely identifying each packet or
packet type. Also the appropriate methods of multiplexing these video data stream packets
with audio data stream packets and ancillary data stream packets into a single data stream
consisting of a sequence of 188-byte transport packets.
Service Information (SI)
In an MPEG data stream, Service information (SI) is included within a DVB MPEG-2 transport
stream to assist the user in selection of services and/or events within the digital multiplex, and
so that the receiver can automatically configure itself for the selected service. Information
carried within SI allows for identification of services or events for the user and may also
provide information on services carried by different multiplexes and even other networks. SI
data complements the Program specific information (PSI) tables by providing other data to aid
automatic tuning of decoders, and information intended for display to the user. In general, SI
augments and extends the relevant PSI specified in ISO/IEC 13818-1 (MPEG-2 Systems), the
Program association table (PAT) and Program map table (PMT).
SFN (Single Frequency
Network)
A network of synchronized DVB-T stations sharing the same radio frequency channel and
transmitting identical signals.
Transmitter
Pylon fitted with antennas which re-transmits channels (digital or analogue) and to which
directional antenna’s should be directed. Note: a transmitter does not necessarily have to
transmit all available channels.
Transport Stream (TS)
In MPEG-2, a packet-based method of multiplexing into a single stream, one or more
packetised elementary streams each consisting of related digital streams of various material.
This material may be video, audio and other information such as teletext, bit-mapped subtitles.
Transport stream packets
A way of breaking up the continuous stream of MPEG compressed video, audio and other
data for ease of passing through various transmission systems such as broadcast. In MPEG-
2, the packet length is 188-bytes including a 4-byte header which contains a ‘PID’ for
identification. The 184 byte payload may include data from the PES packets (i.e. video, audio,
etc.), information on the format of the contents (PSI) and/or adaptation fields or stuffing bytes.
UHF-Channel
In UHF, the channels are numbered from 21 to 69 and in frequency range 470 to 582 MHz
(Band IV) and 582 to 862 MHz (Band V)
Vertical Blanking Interval
(VBI)
Present in conventional, uncompressed TV signals, this unseen space at the top of a TV
picture is now used to carry ancillary data, such as teletext including closed captions.
VHF-Channel
In UHF, the channels are numbered from 5 to 12 and in frequency range 174 to 230 MHz
(Band III)
