Page 134 - Electrical Engineering Dictionary

of these pulses are many times smaller than Cholesky decomposition a matrix-alge-
that of the information symbols leading to braic theorem that states that, for any positive
significantly greater spreading of the signal definite square matrix A, there exists a lower-
T
bandwidth. left triangular matrix G such that A = GG .
chip carrier a low-profile rectangular
chopper See buck converter and DC
component package, usually square, whose
chopper.
semiconductor chip cavity or mounting area
is a large fraction of the package size and
whose external connections are usually on all chopper - depth of modulation a marker
four sides of the package. normally associated with the monitoring of
the depth of modulation of a television broad-
chip chart this term is often used for cast signal on a waveform monitor. The
the “gray scale” chart used in the process of chopper reference is used to set the 0% mod-
aligningtelevisioncamerasystems. Thegray ulation point relative to the video signal. The
scale provides logarithmic reflectance rela- sync signal is typically at the 100% modula-
tionships. tion level.

chip select a control signal input to, e.g., chroma the portion of the video sig-
a memory chip, used to make this particular nal defining the color information in the im-
chip “active” in reading or writing the data age. The chroma signal is defined by changes
bus. Read or write is determined by another in the 3.579545 Mhz interlaced sinewave.
control input signal: the “R/W-signal.” Typ- Phase changes create changes in color, peak-
ically, some of the high order bits from the to-peak changes in the sinewave alter the sat-
CPU’s address bus are decoded to form the uration of the color while changes in the DC
chip select signals. level of the chroma signal alter the luminance
(brightness).
chip-to-chip optical interconnect opti-
cal interconnect in which the source and the
chromatic aberration (1) beam spread-
detector are connected to electronic elements
ing due to different momentum of the par-
in two separate chips.
ticles that are being bent by the quadrupole
fields at different angles.
chirp the varying in time of a carrier fre-
quency signal. See also chirp function. (2) the failure of a lens to simultaneously
focus all colors of light. It arises since the
chirp function a signal whose frequency refractive index of a material depends on the
varies monotonically with time, e.g., a lin- wavelength of light.
ear chirp possesses a linear-frequency or a
quadratic-phase variation.
chromaticity (1) the ratio of tune spread
to momentum spread of the beam. Chro-
chirp signal See chirp function.
maticity affects the focusing and bending
properties of magnets by making them sen-
chirping a shifting of the optical fre-
sitive to particle momentum. This results in
quency often observed in modulated semi-
focusing and bending dispersion of the beam
conductor lasers where the laser gain is mod-
in a manner analogous to an optical system.
ulated at high bandwidth; arises due to the
later portions of the modulating signal seeing (2) specification of color stimuli. The
a different refractive index, or carrier density, chromaticity coordinates are relative RGB
than the earlier portions. values correlated with hue and saturation.

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2000 by CRC Press LLC