wave plate
transparent anisotropic medium
that introduces polarization-dependent phase
shifts on an optical wave.
wave polarization
a description of the
time-varying behavior of the electric field
vector as some fixed point in space. Elliptical
polarization is the most general polarization
and special cases include linear and circular
polarizations.
wave propagation
the transfer of energy
by electromagnetic radiation.
wave winding
an armature winding on a
DC machine in which the two ends of each
coil are connected to bars on opposite sides
of the commutator ring. The wave winding
provides two parallel paths through the ar-
mature winding, regardless of the number of
poles in the machine.
waveform coding
refers to the class of
signal compression methods that are based
on a criterion where the input waveform is
to be resembled as closely as possible ac-
cording to some criterion, e.g., minimum
squared error, by the reproduced coded ver-
sion. Waveform coding contrasts parametric
coding techniques.
waveform distortion
refers to a deviation
from a steady-state clean sine waveform.
waveform interpolation coding
para-
metric speech coding method where a char-
acteristic waveform, a prototype waveform,
is extracted from the speech signal at regu-
lar time instants and the intermediate signal is
interpolated. Waveform interpolation coding
is mostly used in low bit rate speech coding.
wavefront
front of a wave; often a surface
of constant phase.
waveguide
a system of conductive or di-
electric materials in which boundaries and
related dimensions are defined such that
electromagnetic waves propagate within the
bounded region of the structure. Although
most waveguides utilize a hollow or dielec-
tric filled conductive metal tube, a solid di-
electric rod in which the dielectric constant
of the rod is very much different from the di-
electric constant of the surrounding medium
can also be used to guide a wave. Waveguides
rapidly attenuate energy at frequencies below
the waveguide lower cut-off frequency, and
are limited in bandwidth at the upper end of
the frequency spectrum due to wave attenua-
tion as well as undesired mode propagation.
waveguide interconnect
interconnect
that uses a waveguide to connect a source
to a detector. A waveguide is used for im-
plementing a bus. The merits are large band-
width, high speed of propagation, and com-
patibility with integrated optics and opto-
electronics.
waveguide laser
a laser in which amplifi-
cation occurs within a waveguide that is con-
fining the laser modes in the transverse direc-
tion.
wavelength
a constant that describes the
distance a periodic wave must travel in or-
der to repeat itself. For example, if
v(z, t)
is a periodic wave and if the wave travels a
distance
λ, then v(z + λ, t) = v(z, t).
wavelength division multiplexing (WDM)
a technique to increase capacity and through-
put of systems by using a number of wave-
length channels simultaneously.
wavelet
a basis function that is obtained
by translating and dilating a mother wavelet;
it has such properties as smoothness, time-
frequency localization, orthogonality, and/or
symmetry.
wavelet coding
coding a signal by coding
the coefficients of the wavelet transform of
the signal. The discrete wavelet transform is
often used in image compression.
c
2000 by CRC Press LLC