C

Conditional Access module. A unit in the form of a plug-in card which is inserted in a special socket in the digibox to receive encrypted television channels. The CA module is connected to a standardised interface. The viewer can then insert their viewing card into the CA module for access to the television channels.

Cable TV, cable television

The various techniques (including FEC) used for the transport of digital video, audio and data signals via a particular medium (e.g. satellite, cable and terrestrial). The channel coding specifications for interoperable digital systems were developed by the DVB.

More than one satellite located at the same orbital position.

The method of representing information (video, audio, data) with a series of discreet digital codes. Different from "conditional access".

Common Interface Connection for plug-in computer card (PCMCIA) in the receiver designed to carry the conditional access subsystem. In order to increase the usefulness of the Common Interface, seven extensions have been proposed and are on their way to adoption by DVB.

The geographical area covered by a satellite transponder. The area within which good quality reception can be guaranteed. Commonly known as the "footprint". A satellite may have transponders with different coverage areas and even have steerable "antenna beams" which can be aimed at different areas (this may vary during the life of the satellite). Outside the coverage area the signal declines rapidly and reception is normally not acceptable. Variations in signal strength occur here.