Page 42 - Electrical Engineering Dictionary

(2) material that attracts and holds (by Van Advanced Television Research Consor-
der Waal forces) molecular layers of dense tium an organization consisting of David
gases (i.e., very near condensation temper- Sarnoff Research Center, Thompson Con-
atures) on porous high surface/volume ratio sumer Electronics, North American Philips
materials. Corporation, NBC, and Compression Labo-
ratories.
ADTV See advanced digital television.
aeolian vibration a high-frequency me-
chanical vibration of electric power lines
advanced compatible television (ACTV)
caused by wind.
an extended definition television system that
can operate with existing bandwidths on ex-
aerial cable any fully-insulated electric
isting receivers and is compatible with the
power cable which is carried overhead upon
NTSC broadcasting system. The ACTV sys-
poles, as opposed to the use of the more usual
tem was proposed by the Advanced Televi-
overhead bare conductors.
sion Research Consortium and was the first
high definition television (HDTV) system. aerodynamic head See disk head.
HDTV system was tested by the FCC July
17, 1992. The additional picture information AFC See automatic frequency control.
needed to increase the picture width and to
increase the resolution to the HDTV format affine transform a geometric image
is transmitted in an augmented channel as transformationincludingoneormoretransla-
an alternative to simulcast transmission. See tions, rotations, scales, and shears that is rep-
Advanced Television Research Consortium. resented by a 4 × 4 matrix allowing multiple
geometric transformations in one transform
advanced digital television (ADTV) step. Affine transformations are purely lin-
a high definition television (HDTV) digital ear and do not include perspective or warping
transmission television system was proposed transformations.
to the Federal Communications Commission
by the Advanced Television Research Con- AFM See atomic force microscope.
sortium. The ADTV system introduced a
AFT See automatic fine tuning.
layered system to separately describe the dig-
ital transmission system, the video compres-
AFV See audio follow-video switcher.
sion system, and the data packet transport
system. The video compression method uses
AGC See automatic gain control or
a MPEG++ standard that provides for com-
automatic generation control.
patibility with multimedia computing. See
Advanced Television Research Consortium.
agent a computational entity that acts
on behalf of other entities in an autonomous
advanced mobile phone system (AMPS) fashion.
a standard for a cellular radio communi-
cations network originally developed in the agent-based system an application
1970s by AT&T and later adopted as an in- whose component are agents. See also
dustry standard by the U.S.-based Telecom- agent.
munications Industries Association (TIA). It
is the first cellular standard widely deployed aggregation an operation performed on
in North America. It is also referred to as the system variables whose purpose is to collect
analog cellular system. Frequency modula- them in a way enabling order and/or uncer-
tion with 30 kHz channels is used. tainty reduction. For linear systems both

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2000 by CRC Press LLC