Page 34 - Electrical Engineering Dictionary

to deflect light to different angular positions acousto-optics the area of study of in-
based on the frequency of the acoustic wave. teraction of light and sound in media, and
its utilization in applications such as signal
acousto-optic space integrating convolver processing and filtering.
device that is the same as an acousto-optic
space integrating convolver except that it im- ACP See adjacent channel power.
plements the convolution operation.
acquisition (1) in digital communica-
tions systems, the process of acquiring syn-
acousto-optic space integrating correlator
chronism with the received signal. There
an acousto-optic implementation of the cor-
are several levels of acquisitions, and for a
relation function where two RF signals are
given communication system several of them
spatially impressed on two diffracted beams
have to be performed in the process of setting
from Bragg cells, and a Fourier transform
up a communication link: frequency, phase,
lens spatially integrates these beams onto a
spreading code, symbol, frame, etc.
point sensor that generates a photo current
representing the correlation function. (2) in analog communications systems,
the process of initially estimating signal pa-
rameters (for example carrier frequency off-
acousto-optic spectrum analyzer an
set, phase offset) required in order to begin
acousto-optic processor that produces at a
demodulation of the received signal.
photodetector output array the Fourier de-
(3) in vision processing, the process by
composition of the electrical drive signal of
which a scene (physical phenomenon) is
an acousto-optic device.
converted into a suitable format that al-
lows for its storage or retrieval. See also
acousto-optic time integrating convolver
synchronization.
same as the acousto-optic time integrating
correlator, except implements the signal con-
across the line starter a motor starter that
volution operation. See acousto-optic time
applies full line voltage to the motor to start.
integrating correlator.
This is also referred to as “hard starting” be-
cause it causes high starting currents. Larger
acousto-optic time integrating correlator
motors require reduced voltage or “soft start-
an acousto-optic implementation of the cor-
ing.”
relation function where two RF signals are
spatially impressed on two diffracted beams
ACRR See adjacent channel reuse ratio.
from Bragg cells, and a time integrating sen-
sor generates the spatially distributed corre-
ACSR aluminum cable, steel-reinforced.
lation results.
A kind of overhead electric power conduc-
tor made up of a central stranded steel cable
acousto-optic triple product processor overlaid with strands of aluminum.
signal processor that implements a triple inte-
gration operation using generally both space ACT See anticomet tail.
and time dimensions.
action potential a propagating change in
acousto-optic tunable filter (AOTF) an the conductivity and potential across a nerve
acousto-optic device that selects specific op- cell’s membrane; a nerve impulse in common
tical frequencies from a broadband optical parlance.
beam, depending on the number and frequen-
cies of acoustic waves generated in the de- activation function in an artificial neural
vice. network, a function that maps the net output

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