Page 228 - Electrical Engineering Dictionary

dissipation factor (DF) the ratio of the distance profile for convolutional codes,
effective series resistance of a capacitor to its the minimum Hamming weight of all se-
reactance at a specified frequency measured quences of a specific length emerging from
in percentage. Also known as loss tangent. the zero state. A distance profile for one code
is superior to that of another if
dissipation power (1) ratio of real power 1. all values of the distance profiles of the
(in phase power) to reaction power (shifted two codes up to a certain depth p (lower than
◦
90 out of phase). the constraint length) are equal; and
(2) the ratio of the imaginary to real parts 2. the superior distance profile code has
of the complex permittivity, expressed as a higher values of the distance profile for all
dimensionless ratio. depths above the given depth p.

dissipative half-space used for analy- distance protection relaying principle
based upon estimating fault location (dis-
sis of complex systems, it is constructed by
tance) and providing a response based upon
dividing the infinite space in two by some
the distance to the fault.
convenient fashion. The resulting two half-
spaces can both be infinite, or one finite and
distance relay See impedance relay.
one infinite. The resulting half-space is then
filled with a dissipative material (other than
distance resolution delay resolution
a perfect insulator or conductor).
mapped into the spatial domain, measured in
units of distance (meters). Each unit of time
dissipator a form of air terminal which is
delay corresponds to a unit of distance d trav-
meant to prevent lightning strikes to a struc-
eled by the radio wave through the equation
ture by reducing the surface charge on the
earths’s surface in the immediate region of d = cτ,
the structure.
where τ is the delay and c is the speed of
distance Seechamferdistance, chessboard light. Distance resolution gives the smallest
distance, Euclidean distance, Hamming difference in path length resolved by a signal.
distance, Hausdorff distance, inter-feature Is also a measure of the spatial resolution ca-
distance, Mahalanobis distance, Manhattan pability of a signal (or measurement system).
distance.
distance transform a map of all the pixels
distance between symbol strings a mea- in a shape showing the closest distance of
sure of the difference between two symbol each point in the shape from the background;
strings. The most frequently used distance also, an image in which the distance maps of
measures between two strings include Ham- all the shapes in the image are indicated. See
ming distance, edit or Levenshtein distance, also distance.
and maximum posterior probability distance.
distortion (1) addition of an unwanted
See also Hamming distance, edit distance,
component to an electronic signal.
maximum posterior probability distance.
(2) undesired change in a signal’s ampli-
tude and/or phase as the result of it passing
distance measure a function d(x, y) de-
through an active nonlinear circuit. Numer-
fined on a metric space, such that
ous figures of merit have been adopted to de-
d(x, y) ≥ 0, where = holds iff x = y,
scribe various aspects of signal distortion.
d(x, y) = d(y, x), and
d(x, y) ≤ d(s, z) + d(z, y). distortion cross modulation nonlinear
See also similarity measure. distortion of a system or carrier signal char-

c
2000 by CRC Press LLC