| AAL |
ATM Adaptation Layer. The part of the ATM protocol that breaks up application data packets into ATM cells. There are six ATM adaptation layers:AAL-1: Constant Bit Rate (CBR)AAL-2: Variable Bit Rate (VBR)AAL-3/4: Available Bit Rate (ABR)AAL-5: Unspecified Bit Rate (UBR)AAL-6: MPEG-2.
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| ADSL |
Asymmetric Digital Subscriber Line. Modems using twisted pair copper wiring to transmit data asymmetrically. Data rates depend on distance, but maximum is 9 Mbits/s downstream and 800 kbits/s upstream.
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| AEC |
Acoustic Echo Cancellation. A method for removing acoustic echoes returned from a room that would otherwise cause closed-loop feedback in a full-duplex conferencing system.
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| AGC |
Automatic Gain Control. A method of automatically controlling the gain of an audio path. May be used as a sub component of an audio echo canceller.
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| AMR |
Adaptive Multi-Rate. An audio coder/decoder.
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| API |
Application Programming Interface. A defined set of calling conventions allowing a software application to access a particular set of services.
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| Artefact |
An unwanted visual aberration in a video image.
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| ASCll |
American Standard Code for Information Interchange. A method of encoding characters into bits. ASCII is the US version of the International Standards Organizations (ISO) character encoding set.
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| ASN.1 |
Abstract Syntax Notation number one. Language for abstractly describing messages to be exchanged over a variety of networks. See alsoX.680 to X.683. Used in conjunction with encoding rules such as BER or PER.
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| Aspect Ratio |
The relationship between the width and the height of an image. To avoid distortion this ratio must be kept constant when displaying an image on different screens.
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| AT-Commands |
Attention Commands. Text based protocol allowing a DTE to communicate with a DCE.
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| ATM |
Asynchronous Transfer Mode: A high-speed cell (i.e. packet) based data transmission protocol.
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