ADR
ASTRA Digital Radio. Transmission system used by ASTRA in order to broadcast twelve stereo radio programmes in hi-fi quality on only one sound subcarrier of a satellite TV transponder.

AFC
Automatic Frequency Control. Electronic circuit that connects the undesirably deviations from a selected frequency in the receiver, in order to stabilize reception of a channel.

ASTRA
System currently comprising 10 satellites (ASTRA 1A to 1H) at 19.2° East, and ASTRA 2A at 28.2° East. (Societe Europenne des Satellites) based in Betzdorf, Luxembourg.

Audio
Sound signal. That part of a TV or radio transmission that is heard.

Audio Bandwidth
Term used for the sum total (range) of frequencies contained within a specific band.

AV
Abbreviation used to mark switches, buttons or connections intended to connect or activate audio-visual (audio and/or video) equipment. For instance, the AV connection between the receiver and the TV set is usually brought about by means of a Scart cable, as this provides better quality than using antenna cable.

AZ-EL
Abbreviation for a mounting system for parabolic dish antenna that can be adjusted in two axes - azimuth and elevation.

Azimuth
The compass direction of the satellite, as seen from the viewer's location, eg East, West, etc.