18WuD2x

scan rate • scientific notation 611
scan rate 1. The rate at which a controlled quantity
is checked periodically by a control computer.
2. See SCANNING FREQUENCY.
scan tuning Repetitive, automatic sweeping of a
frequency band by a tuned circuit containing a
varactor, whose capacitance is periodically varied
by a sawtooth voltage.
SCARA Abbreviation of SELECTIVE COMPLIANCE
ASSEMBLY ROBOT ARM.
SCA subcarrier An auxiliary carrier (commonly
67 kHz) superimposed on a main frequencymodulated
carrier to convey subsidiary communications,
such as music without commercials. Also see
SUBSIDIARY COMMUNICATION AUTHORIZATION.
scatter To disperse or diffuse transmitted electromagnetic
radiation.
scattering 1. The tendency of a concentrated beam
of energy to be spread out when it passes through
a given medium or substance. 2. The spreading
out of radio waves as they pass through the ionosphere
or troposphere.
schematic diagram An electronic circuit diagram.
Also called WIRING DIAGRAM and schematic.
schematic symbol A graphic symbol used to represent
electronic components in a circuit diagram.
Schering bridge A four-arm capacitance bridge in
which the unknown capacitance is compared
with a standard capacitance. This bridge is frequently
used in testing electrolytic capacitors, to
which a direct-current polarizing voltage is applied
during the measurement.
R X balance R 1
C X
R X
C 1
R 2
C S
C X = C S (R 2 /R 1 )
R X = R 1 (C 1 /C S )
Ionosphere
C X
balance
Transmitting
station
Earth
scattering
Receiving
station
scatter read In data processing, to distribute data
from an input record to several storage areas.
scatter transmission See BACK SCATTER and
FORWARD SCATTER.
S C band A section of the S BAND extending from
2000 to 2400 MHz.
scc Abbreviation of SINGLE-COTTON-COVERED
(WIRE).
SCDSB Abbreviation of SUPPRESSED CARRIER
DOUBLE-SIDEBAND (see DOUBLE-SIDEBAND
SUPPRESSED CARRIER).
SCE Abbreviation of saturated calomel electrode.
sce Abbreviation of SINGLE-COTTON-ENAMELED
(WIRE).
SCEPTRON Acronym for SPECTRAL COMPARA-
TIVE PATTERN RECOGNIZER.
schedule In computer operations, to establish the
order of importance of jobs to be run, and assign
the necessary resources for those jobs.
schedule method A method of waveform analysis
involving the evaluation of instantaneous amplitudes
at numerous points in time. The values are
obtained at specific intervals from the image of
one complete wave cycle, as displayed on an oscilloscope
or plotted on a graph.
Schering bridge
Schmidt optical system In projection television, a
lens system used between the bright-image picture
tube and the screen.
Schmitt limiter See SCHMITT TRIGGER.
Schmitt trigger A multivibrator that produces
uniform-amplitude output pulses from a variable-amplitude
input signal. This circuit has
many applications, one being the conversion of a
sine wave into a square wave.
Schottky diode A solid-state diode in which a
metal and a semiconductor form the pn junction.
Electrons injected into the metal have a higher
energy level than the charge carriers in a semiconductor,
and energy storage at the junction is
low because current flow is not accompanied by
hole movement. Also known as HOT-CARRIER
DIODE.
Schottky logic A form of integrated-injection logic
with enhanced operating speed.
Schottky noise The random noise resulting from
the emission of charged particles, usually electrons
or holes, from an electrode in an amplifying
device. This noise is usually of a wideband nature.
scientific language Any computer programming
language used primarily for mathematical or scientific
applications.
scientific notation The expression of very large
and very small numbers as a fixed-point part
(mantissa) and a power of the radix (usually 10).