Page 178 - Electrical Engineering Dictionary

satisfies −1 ≤ ρ ≤ 1, where |ρ|= 1 implies correspondence problem the problem of
a deterministic linear relationship between x matching points in one image with their cor-
and y, and ρ = 0 implies lack of correlation. responding points in a second image.
See also correlation.
corresponding point a point, in a set of
correlation detector the optimum struc- images representing a different view of the
ture for detecting coherent signals in the pres- same scene, onto which the same physical
ence of additive white Gaussian noise. point in the real world is projected.

corrugated horn a horn with grooves on
correlation function a mathematical de-
its inner walls. The grooves create the same
scription that describes the common relation-
boundary conditions on all four walls of the
ship between two processes. For a single
horn. This results in the elimination of spuri-
time dependent quantity, the autocorrelation
ous diffraction at the edges of the horn aper-
function describes the loss of information in
ture.
the process description of the quantity. See
autocorrelation function.
coset leader each possible error pattern
of the code word representing the left-most
correlation peak detector a photodetec-
column of the standard array.
tor array that detects and outputs only the
peak in a spatial correlation function. cosinemodulatedfilterbank afilterbank
with each of its analysis filters and synthe-
correlation receiver a receiver utilizing sis filters being the modulation of a low-pass
the autocorrelation or cross-correlation prop- prototype filter by a cosine function. In the
erties of the transmitted signal to detect the frequency domain, it is equivalent to shifting
desired information from the received signal. the low-pass prototype filter by different fre-
A correlation receiver is theoretically equiv- quencies to form a bank of bandpass filters
alent to a matched filter receiver. Correlation covering the entire frequency band.
receivers are often used in spread spectrum
systems and channel measurement systems. cosine roll-off filter a filter that has an
impulse response which satisfies the Nyquist
correlation sidelobes the correlation I criterion for zero intersymbol interference.
function other than the peak; particularly The filter has the following transfer function.
where signals are designed to give a sharply  π(1−α)
 1,
 |ω|≤ T

peaked correlation function.  cos 2 T

4α
H(ω) = π(1−α) π(1−α) π(1+α)
 |ω|− , < |ω| <
 T T T


 π(1+α)
correlation similarity the (unnormal- 0, |ω|≥ T
ized) correlation of two real vectors x = where T is the transmitted symbol period and
(x 0 ,...,x n ) and (y 0 ,...,y n ) is defined as α is a parameter that is known as the excess
their inner product: bandwidth (0 ≤ α ≤ 1). The case α = 0
yields the ideal low-pass filter, and the case
n
X α = 1 yields a filter referred to as the raised
C = x i y i .
cosine filter.
i=1
cosine transform a transform that con-
sists of a set of basis functions, which are co-
correlator a circuit that calculates the sine functions. Usually referred to as discrete
correlation function. See also correlation cosine transform. See also discrete cosine
function. transform.
c
2000 by CRC Press LLC