Harmonic ProView 7000 User Manual page 195

Glossary
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Numerics A B
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AAL5
ATM Adaptation Layer 5. Performs the functions necessary to adapt frame oriented data
information, such as MPEG transport streams and IP datagrams, to the ATM cell format.
AC-3
Also known as Dolby Digital.
ACG
Access Control Group. An identifier that links control words (CWs), entitlement control
messages (ECMs), and packet identifiers (PIDs) to a common group.
ACM
A card for the MN20 multiplex. The ACM supports DES and DVB protocols.
adapter
A circuit board in a Harmonic encoder. Adapters have input or output ports. Also known as a
card or a blade.
AEM
Audio adapter used in MN20 remultiplex, it can compress two stereo pairs of either analog or
digital audio into the MPEG-1 layer II.
AES3 Standard
The standard for serial transport of digital audio in professional devices, developed by the Audio
Engineering Society (AES) originally in 1992. It has been revised a number of times since then,
with the current revision published in 2010, breaking the original document into multiple Parts.
Some obsolete references term it "AES/EBU," since the EBU also published the original
document in 1992 as EBU Tech. 3250.
AFD
Active Format Descriptor. Signaling describes certain spatial characteristics of a high definition or
standard definition video image. AFD and Bar Data are intended to be broadcast with the video
signal that they describe. AFD information is intended to assist DTV displays in optimizing the
displayed images. AFD may also be used by intermediate professional video equipment in
conversion of video images of one aspect ratio into a image of another aspect ratio. Bar Data
information is used to signal the precise unused areas of active video when the active image does
not completely fill the picture area, in particular widescreen cinema material carried letterboxed in
a frame with bars top and bottom. AFD is documented by SMPTE 2016 (multiple part
document) and its carriage in compressed video is documented in DVB/ETSI TS 101 154, ATSC
A/53 Part 4, ATSC A/72 Part 1, SCTE 128, and other standards.
AGC
Automatic Gain Control. Keeps the output signal of a circuit constant while the input signal
amplitude varies.
© 2011 Harmonic Inc.
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ProView 7000 v.2.4, Rev. A
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