Annex A

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 Mbps. 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 authorized subscribers through the transmission

 

of encrypted signals and the programmable regulation of their

 

decryption by a system such as viewing cards.

CAT

Conditional Access Table: Part of the MPEG-2 Program Specific

 

Information (PSI) data. Mandatory for MPEG-2 compliance if CA is

 

in use.

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.

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.

Channel Coding

A way of encoding data in a communications channel that adds

 

patterns of redundancy into the transmission path in order to

 

improve the error rate. Such methods are widely used in wireless

 

communications.

EN/LZT 790 0005 R1A

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