TANDBERG E5780, Справочное руководство

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Glossary
Page A-2 Reference Guide: evolution 5000 E5780 and E5782 Encoder
ST.RE.E10135.4
ATM
Asynchronous Transfer Mode: A connection orientated, cell based, data transport technology designed for
Broadband ISDN (B-ISDN). It provides a circuit-switched bandwidth-on-demand carrier system, with the flexibility
of packet switching. It offers low end-to-end delays and (negotiable on call set-up) Quality of Service guarantees.
Asynchronous refers to the sporadic nature of the data being transmitted. Cells are transmitted only when data is
to be sent; therefore the time interval between cells varies according to the availability of data.
ATSC Advanced Television Standards Committee: An organisation founded in 1983 to research and develop a digital
TV standard for the U.S.A. In late 1996, the FCC adopted the ATSC standard, the digital counterpart of the NTSC
standard.
B3ZS
Bipolar with Three Zero Substitution: A method of eliminating long zero strings in a transmission. It is used to
ensure a sufficient number of transitions to maintain system synchronisation when the user data stream contains
an insufficient number of 1s to do so. B3ZS is the North American equivalent of the European HDB3.
Backward Compatibility Refers to hardware or software that is compatible with earlier versions.
BAT Bouquet Association Table: Part of the service information data. The BAT provides information about bouquets.
It gives the name of the bouquet and a list of associated services.
baud rate
The rate of transfer of digital data when the data comprises information symbols that may consist of a number of
possible states. Equivalent to bitrate when the symbols only have two states (1 and 0). Measured in Baud.
BDU Bitstream Data Unit is a section of Vc-1 bitstream that is self-contained.
BER Bit Error Rate: A measure of transmission quality. The rate at which errors occur in the transmission of data bits
over a link. It is generally shown as a negative exponent, (e.g. 10
-7
means that 1 in 10,000,000 bits are in error).
BISS Basic Interoperable Scrambling System: Non-proprietary encryption from EBU (Tech3290).
Bitrate The rate of transfer of digital data when the data comprises two logic states, 1 and 0. Measured in bit/s.
Block; Pixel Block An 8-row by 8-column matrix of luminance sample values, or 64 DCT coefficients (source, quantised, or
dequantised).
Bouquet A collection of services (TV, radio, and data, or any combination of the three) grouped and sold together, and
identified in the SI as a group. A single service may be in several bouquets.
B-Picture; B-Frame Bi-directionally Predictive Coded Picture/Frame: A picture that is coded using motion-compensated prediction
from previous I or P frames (forward prediction) and/or future I or P frames (backward prediction). B frames are not
used in any prediction.
BPSK Binary Phase Shift Keying: A data modulation technique.
Buffer A memory store used to provide a consistent rate of data flow.
BW
Bandwidth: The transmission capacity of an electronic line such as (among others) a communications network,
computer bus, or broadcast link. It is expressed in bits per second, bytes per second or in Hertz (cycles per
second). When expressed in Hertz, the frequency may be a greater number than the actual bits per second,
because the bandwidth is the difference between the lowest and highest frequencies transmitted. High bandwidth
allows fast transmission or high-volume transmission.
Byte-mode Each byte is delivered separately in the ASI Transport Stream, with stuffing data added between the Bytes to
increase the data rate to 270 Mbit/s. See DVB Document A010 rev. 1, Section B3.3, (ASI) Layer-2 Transport
Protocol.
CA
Conditional Access: The technology used to control the access to viewing services to authorised subscribers
through the transmission of encrypted signals and the programmable regulation of their decryption by a system
such as viewing cards.
CABAC Context Adaptive Binary Arithmetic Coding is a form of entropy coding used in H.264 that has greater coding
efficiency than CAVLC but is more computationally expensive.
CAT Conditional Access Table: Part of the MPEG-2 Program Specific Information (PSI) data. Mandatory for MPEG-2
compliance if CA is in use.
CAVLC Context Adaptive Variable Length Coding is a form of entropy coding used in H.264 that has lower coding
efficiency than CABAC but is less computationally expensive.
C-Band The portion of the electromagnetic spectrum, which spans the frequency range of approximately 4 GHz to 6 GHz.
Used by communications satellites. Preferred in tropical climates because it is not susceptible to fading.
CBR Constant Bitrate where the bitrate of the bitstream out of the encoder remains constant over an extended period
of time within the buffer limits of the decoder.
CCIR See: ITU-R.
CCITT See: ITU-T.
Channel A narrow range of frequencies, part of a frequency band, for the transmission of radio and television signals
without interference from other channels.
In the case of OFDM, a large number of carriers spaced apart at precise frequencies are allocated to a channel.