18WuD2x

long-term input offset voltage stability • Lorentz force 419
which the input offset voltage in an integrated circuit
stays stable over long periods of time.
long-term stability Stability reckoned over a period
of weeks, months or years, as contrasted to
that noted for brief intervals of time (minutes or
hours).
long throw A speaker design term that describes a
woofer moving through long excursions; the objective
is to provide good low-frequency response
with low distortion.
long waves Low-frequency radio waves, particularly
those in the frequency range of 30 kHz to
300 kHz (10 km to 1 km).
long-wire antenna A horizontal or sloping wire antenna
measuring a full wavelength or more and
fed at a high-current point or at one end. As the
wire is made longer, the main radiation/response
lobes get more nearly in line with the antenna,
and their amplitudes increase. As the wire is
made shorter, the main lobes get farther from the
axis of the antenna, and their amplitudes decrease.
This antenna can produce high gain and
excellent low-angle radiation, provided it is
straight, is at least several wavelengths long, and
is clear of obstructions. However, it cannot be rotated
conveniently to change the direction in
which maximum gain occurs. Also, a great deal of
real estate is needed at medium and high frequencies.
lookup A computer programming technique in
which a data item identified by a key is selected
from an array.
loop 1. An electrical circuit consisting of elements
connected in series. 2. In a standing-wave system,
a maximum-response point (e.g., current
loop and voltage loop). Compare NODE, 2. 3. See
LOOP ANTENNA. 4. A signal path (e.g., feedback
loop). 5. A one- or two-turn coil for lowimpedance
coupling. Also see LINK, 1. 6. In a
computer program run, the repetitious execution
of a series of instructions that terminates when
some specified condition is satisfied by a relational
test, at which point the next instruction in
the main program is obeyed.
loop antenna 1. A small portable receiving antenna
in the form of a wire coil. 2. A half-wave
conductor bent into a circle or square. The conductor
is broken at the point opposite the feed
point. It can be used for transmitting and receiving.
3. A full-wavelength, continuous conductor
bent into a circle or square. It can be used for
transmitting and receiving.
loop checking A method of checking the accuracy
of data transmitted over a data link by returning
signals received at one terminal to the transmitting
terminal for comparison with the original
data.
looped amplification See FEEDBACK FACTOR.
looping plug A double phone-plug unit for simultaneously
plugging into two phone jacks. Completes
(loops) the circuit between the two jacks.
looping plug
loop-input signal A signal introduced into a feedback
control loop.
loop pulsing The regular, intermittent breaking of
the direct-current path at the transmitting end of
a transmission line; also called DIAL PULSING.
loop resistance The resistance of the electrical
path around a complete loop (see LOOP, 1).
loop response time In a security system, the
length of time between the first sensing of an abnormal
condition (e.g., an intrusion) and the
recognition of that condition by the controller.
loopstick antenna See FERRITE-ROD ANTENNA.
loop test A means of locating a discontinuity in a
circuit by creating a closed loop, including the
suspected fault point.
loose coupling Coupling that transfers only small
amounts of energy, as when a primary and secondary
coil are spaced so far apart that the coefficient
of coupling is small. Compare CLOSE
COUPLING.
loosely coupled twin In computer operations, a
system in which two processors, each having its
own operating system, are used with switches so
that they can use common peripherals. Also see
SWITCH.
lopplar Acronym for laser Doppler radar. Also abbreviated
as ladar.
lorac A radio-navigation system that operates by
means of phase comparison. Similar to LORAN.
Trade name of Seismograph Service Corporation.
loran A long-range radionavigation system in
which two pairs of ground stations transmit
pulsed signals that are used by aircraft and ships
to determine their positions. The name is an
acronym for long-range navigation.
loran C A radionavigation system that operates at
a frequency of 100 kHz. It operates on the hyperbolic
principle.
loran D A radionavigation system similar to loran
C. It is used by aircraft, operates independent of
ground stations, and prevents unwanted enemy
detection of aircraft position.
Lorentz force For a charge Q moving with velocity
v in a magnetic field B and an electric field E, the
force F = Q(E + (v × B)).