Page 243 - Electrical Engineering Dictionary

nically erasable programmable read-only
memory.
E earth electrode system a network of elec-

trically interconnected rods, plates, mats, or
grids installed for the purpose of establishing
a low-resistance contact with earth. The de-
E modes the wave solutions with the zero sign objective for resistance to earth of this
magnetic field component along the direction subsystem should not exceed 10 .
of propagation. Also known as transverse
magnetic (TM) modes. Earth station the interface point for com-
munications to and from a satellite. An earth
E plane in measuring an antenna’s radia- station (also known as a hub) consists of an
antenna and transmit and receive subsystems.
tion pattern, the plane that contains the cur-
rent in the element and therefore the electric
earth wire an overhead wire which is
field intensity vector field. This plane is per-
maintained at ground potential for purposes
pendicular to the H plane cut.
of lightning shielding and system grounding.
E-beam excitation See electron beam
earthing See grounding.
excitation.
EBCDIC See extended binary-coded-
E-plane sectoral horn a horn antenna
decimal inter-change code.
where the aperture is formed by flaring the
walls in the direction of the E plane. The H-
ebullient heat transfer the heat transfer
plane dimension is left unchanged from that
process associated with the formation and re-
of the waveguide feed.
lease of vapor bubbles on a heated surface.
early stopping a technique applied to net-
ECC See error-correcting code.
work training that is aimed at assuring good
generalization performance. Training on a
ECG See electrocardiography.
finite set of data eventually leads to over-
fitting, and this can be avoided by period- echo cancellation technique that re-
ically assessing generalization performance moves the unwanted effects that result from
on a set of test data. As training proceeds, impedance mismatch. Echo cancellation fre-
network performance on both the training set quently makes use of adaptive filtering algo-
and the test set gradually improves, but even- rithms that can be realized by digital filters.
tually performance on the test set begins to
deteriorate, indicating that training should be echo canceller in telephony, a filter that
stopped. The set of network weights that give removes echoes caused by leakage of the
the best performance on the test data should transmitted signal through a hybrid. The hy-
be employed in the trained network. brid is the interface between two wire (lo-
cal) and four wire (long-distance) facilities,
early vision the set of (mainly perceptual) and separates inbound and outbound signals.
processes occurring at an early stage of the Echo cancellers are used in analog telephony
vision process, typically at the retinal level. to cancel echoes from signals that traverse
the entire round-trip connection, and in full-
EAROM electrically alterable program- duplex voiceband modems, where the echo is
mable read-only memory. See also electro- due to leakage through the near-end hybrid.

c
2000 by CRC Press LLC