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collinear antenna A broadside directional antenna faulty color reproduction resulting from incom-
consisting of two or more half-wave radiators; plete separation of the red, green, and blue chan-
the current is kept in phase in each section by nels.
quarter-wave stubs between each radiating sec- color-coordinate transformation In a color televi-

tion. The radiators are stacked end to end horizon- sion system, the computation (performed electri-
tally or vertically. Also called FRANKLIN ANTENNA. cally in the system) of the tristimulus (primary)

Collins coupler A single-section, pi-filter circuit, values with reference to one set of primaries, from
used to match a radio transmitter to a wide range the same colors derived from another set of pri-
of antenna impedances. Also called pi coupler and maries.
Collins network. color depth An expression for the extent to which
collodion A viscous solution of pyroxylin and a an image can accurately render color. Generally
solvent (such as acetone, alcohol, or ether) some- expressed in bits or in number of colors. Some
times used as a binding agent for coils and other systems can reproduce millions of different colors.
components. color-difference signal Designated B-Y, G-Y, and
cologarithm Abbreviation, colog. The logarithm of R-Y. The signal resulting from reducing the am-

the reciprocal of a number; colog x = log (1/x) = plitude of a color signal by an amount equal to
log x “1 = “log x. the luminance-signal amplitude. Also see B-Y
color A perceived characteristic, and a direct func- SIGNAL, G-Y SIGNAL, and R-Y SIGNAL.
tion, of visible-light wavelength. Seen by the hu- color dot 1. A phosphor spot on the screen of a
man eye as a spectrum of hues, ranging from red color television picture tube. 2. One of the spots
at the longest visible wavelengths, through or- stamped on a capacitor, indicating the capaci-
ange, yellow, green, blue, indigo, and finally violet tance, voltage, and tolerance (see COLOR CODE,
at the shortest visible wavelengths. See HUE. 1). 3. A spot stamped on a resistor, indicating the
coloration In audio applications, a blending of number of zeros to be added to the value indi-
sounds as a result of mixing among components cated by the color bands.
at different frequencies. Sometimes this is done color edging In a color television picture, an aber-
deliberately; in other instances, it is undesirable. ration consisting of false color at the boundaries
color balance In a color television receiver, adjust- between areas of different color.
ment of the beam intensities of the individual color encoder In a color television transmitter, the
guns of a three-gun picture tube. Compensates circuit or channel in which the camera signals
for the difference in light emissivity of the red, and the chrominance subcarrier are combined
green, and blue phosphors on the tube screen. into the color-picture signal.
color bar-dot generator A radio-frequency (RF) color equation A mathematical means of deter-
signal generator that produces a bar or dot pat- mining the resultant color obtained by adding
tern on the screen of a color television picture primary colors in various proportions.
tube. Used for testing and alignment. color fidelity The faithfulness with which a color
color-bar pattern A color television test pattern of television system, lens, or film reproduces the
vertical bars”each of a different color. colors of a scene.
color breakup A transient separation of a color color filter A transparent plate or film that trans-
television picture into its red, green, and blue mits light of a desired color, and eliminates or at-
components, as a result of a sudden disturbance tenuates all other colors.
of viewing conditions (blinking of eyes, moving of color flicker In a color television system, image in-
head, intermittent blocking of screen, etc.). stability that occurs when the luminance and
color burst As a phase reference for the 3.579545- chromaticity both fluctuate.
MHz oscillator in a color television receiver, ap- color fringing In a color television picture, false
proximately nine cycles of the chrominance color around objects, sometimes causing them to
subcarrier added to the back porch of the hori- appear separated into different colors.

color generator • color spectrum

color generator A special radio-frequency (RF) sig- image. 2. In color television, the combination of
nal generator to adjust or troubleshoot a color chrominance and luminance signals minus
television receiver. The color signals it delivers blanking and sync signals.
are identical to those produced by a broadcast color picture tube A specialized type of cathode-
station. ray tube (CRT), used in color television receivers
color graphics Computer graphics displayed in and computer displays. Three different images
color on a cathode-ray tube (CRT) or liquid- are produced: one in red, one in blue, and one in
crystal display (LCD). green. The three monochrome images are com-
colorimeter A device used to quantitatively mea- bined to form a complete color image.
sure the color intensity of a sample relative to a color primaries 1. Also called additive primaries or
standard. primary colors. In color television, the hues red
colorimetric A characteristic of visible light, repre- (R), green (G), and blue (B). When these colors are
senting the wavelength concentration. Refers to mixed in various ratios, any visual color can re-
the perceived color of a light beam. sult. 2. Also called subtractive primaries or pri-
colorimetry The science and art of color measure- mary pigments. In color printing, the hues
ment. magenta (M), cyan (C), and yellow (Y). These
color killer In a color television receiver, a circuit roughly correspond to red (R), blue (B) and yellow
that, in the absence of a color signal, delivers a (Y). Sometimes black (K) is also included. When
negative bias to cut off the bandpass amplifier. these pigments are mixed in various ratios, any
color match In photometry, the condition in which visual pigment can result.
color agreement exists between the halves of an color purity The ratio of wanted to unwanted com-
area. Also see COLOR MATCHING. ponents in a color. In a pure color, there are no
color matching The art of selecting colors that are components other than those required to produce
identical in hue, saturation, and brilliance. This the color. Color, in this context, includes white,
can be done with the unaided eye or with the help black, and all shades of gray.
of an instrument. color-purity magnet A permanent magnet on the
color media Substances that transmit essentially neck of a color television picture tube, used to
one color of visible light while blocking other col- help ensure color purity by maintaining proper
ors. displacement of the electron beam.
color meter A photoelectric instrument for mea- color registration In color television reception, the
suring color values, and comparing and matching precise superimposition of red, green, and blue so
colors. that the composite is free from COLOR EDGING.
color mixture An additive combination of two or color rendering index A mathematical expression
more colors. Thus, red + yellow = orange, blue + defining the effect of the color of a light source on
red = violet, red + blue + green = white, etc. an object. For example, in red light, a blue object
color oscillator The oscillator in a color television appears nearly black.
receiver that coordinates the color response. This color sampling rate The number of times per sec-
oscillator is operated at 3.579545 MHz, to within ond that each primary color is sampled in a color
plus or minus 10 Hz. television receiver.
color palette In a color video image, the total num- color saturation A measure of the purity of a hue.
ber of possible colors that can be displayed. The extent to which a hue is without a white com-
color phase In color television, the phase differ- ponent; 100% saturation indicates a complete
ence between an I or Q chrominance primary sig- absence of white.
nal and the chrominance carrier reference. color sensing In machine vision systems, the abil-
color-phase diagram In color television, a quad- ity to distinguish between light of different wave-
rant diagram showing (for each of the three pri- lengths. Usually done with red, green and blue
mary and complementary colors) the difference in color filters and three separate cameras.
phase between the color-burst signal and the color sensitivity 1. The degree of which a photo-
chrominance signal, as well as the peak ampli- sensitive device, such as a photocell or camera
tude of the chrominance signal. Also shown are tube, responds to various colors of light. 2. The
the peak amplitude and polarity of both in-phase degree to which photographic film responds to
and quadrature components required for the various colors of light.
chrominance signals. For color TV receiver ad- color signal See COLOR PICTURE SIGNAL.
justment, the color-phase diagram is displayed, color spectrum The band of electromagnetic en-
in effect, by a VECTORSCOPE when a suitable ergy containing visible light; it extends from red
signal from a color generator is applied to the re- (at the longest wavelengths) to violet (at the short-
ceiver. est). Commonly measured in nanometers (nm),
where 1 nm = 10“9 m. Also expressed in
color picture signal 1. In color television and/or
Angstroms, where 1 Angstrom = 10“10 m = 0.1
computer graphics, an electrical signal contain-
ing components corresponding to the hue, satu- nm. In order of decreasing wavelength, the colors
ration, and brilliance of a fixed or changing visual are red at 750 to 700 nm (7500 to 7000
128 color spectrum • coma lobes

as violet, blue, green, yellow, orange, and red, in
ultraviolet, order of increasing intensity.
Xrays, Colpitts oscillator A radio-frequency (RF) oscilla-
Gamma rays tor that uses a single, untapped inductor. A com-
bination of two fixed capacitors in series is
Violet 0.4
connected in parallel with the inductor. The feed-

Wavelength, µm
back is controlled by the ratio of capacitances. A
Blue 0.5
permeability-tuned coil or a roller inductor can be
Green used to obtain variable-frequency operation. Sta-
Yellow 0.6 bility is enhanced when the output of the oscilla-
Orange tor is taken from the emitter or source portion of
Red the circuit. To prevent the output signal from be-
ing short-circuited to ground, an RF choke is con-
To nected in series with the emitter or source.
infared, Compare HARTLEY OSCILLATOR.
radio waves

color spectrum

Angstroms), orange, yellow, green, blue, indigo,
and violet at 410 to 390 nm (4100 to 3900
color subcarrier A modulated monochrome signal
whose sidebands convey color information.
color-sync signal See COLOR BURST.
color system Also called RGB color model. A means
of representing a color in terms of mathematical
coordinates. This can be done in three dimen-
sions because there are three COLOR PRI-
MARIES. Each color primary is represented by an Colpitts oscillator
axis. Any COMPOSITE COLOR can be repre-
sented by a unique vector. The relative amount of
each color primary is given by the length of the columbium Symbol, Cb. The former name of the
composite-color vector components along each metallic element niobium. Atomic number, 41.
axis. Atomic weight, 92.9064.
color television Television in which the picture column See CARD COLUMN.
approximates natural color. It operates on the ba- columnar graph A graphical presentation of data,
sis of mixing three primary colors (red, blue, and in which the ordinates are represented by vertical
green) of phosphors on the picture tube screen. columns whose height depends on the value.
color television receiver A television receiver de- Commonly used in presentation graphics, but less
signed to reproduce color pictures. common in analytical graphics.
color television signal The signal transmitted by column binary Binary number representation on
a color television transmitter, containing all of the punched cards, wherein consecutive digits corre-
information needed to reproduce a complete, full- spond to consecutive column punching positions.
color, moving image. column speaker An acoustic speaker with a long
color transmission The television transmission of cabinet, so that a large column of air is used for
a picture in color. resonating or reinforcing purposes. This type of
color triad On the screen of a color picture tube, speaker radiates over a wide azimuth angle, while
one of the color cells, each of which contains one providing a narrow beam in the elevation plane.
of the three phosphor dots: red, green, and blue. column split On a punched card machine, the de-
color triangle A triangle that can be inscribed on a vice for reading, as two separate characters or
chromaticity diagram to reveal the chromaticity codes, two parts of a single column.
range resulting from adding the three color pri- COM 1. Abbreviation for communications port.
maries. 2. Abbreviation for computer output on microfilm.
color TV signal The complete signal (video, color, coma An aberration that causes the beam spot on
and sync components) required for transmitting a the screen of a cathode-ray tube to resemble a
picture in color. comet.
color weather radar A computer-enhanced radar coma lobes An aberration in the radiation or re-
rendition of weather patterns, usually showing sponse pattern of a dish antenna that occurs
various intensities of precipitation as different when the radiating element is not exactly at the
colors. Commonly, areas of precipitation show up focal point of the reflector. When the directional
coma lobes • commercial data processing

pattern is altered by moving the driven element, combination speaker Two or more loudspeakers
rather than turning the entire antenna, these combined into one (e.g., a COAXIAL SPEAKER).
lobes appear. combination tone An acoustic tone resulting from
comb amplifier An arrangement of several sharply the combination of two other acoustic tones. If
tuned bandpass amplifiers whose inputs are con- the original tones have frequencies f1 and f2
nected in parallel and whose outputs are sepa- (where f1 is higher than f2), then the first-order
rate; the amplifiers separate various frequencies combination frequencies are f1 + f2 and f1 “ f2.
from a multifrequency input signal. The name is Higher-order combination tones can result from
derived from the comb-like appearance of the re- mixing among the original tones and the first-
sponse pattern of various output peaks displayed order combination tones.
along a frequency-base axis. combinatorial logic A form of digital logic, in
comb filter A selective device that passes several which the output states depend on the input
narrow bands of frequencies within a larger band, states, but on no other factor.
while rejecting frequencies in between the narrow combined head See READ-WRITE HEAD.
bands. So called because its frequency-response combined reactance The net reactance (X) in a
curve resembles the teeth of a comb when ob- circuit, obtained by vectorially adding the induc-
served on a spectrum analyzer. Also see COMB tive reactance (XL ) and the capacitive reactance
combiner A circuit or device for mixing various sig-
nals to form a new signal. Also see MIXER.
combiner circuit In a color television camera, the
circuit that combines the chroma and luminance
with the sync.

comeback A spurious response in a bandpass or
band-rejection filter, at a frequency well above or
below the passband or stopband.
command 1. In computer operations, the group of
selected pulses or other signals that cause the
Frequency computer to execute a step in its program. 2. In-
comb filter response command chain Part of a computer operation car-
ried out independently as a series of input/
output instructions.
comb generator 1. A signal generator that pro-
command control In automation, electronic con-
vides outputs at evenly spaced frequencies. So
trol, and computer operations, the performance
called because, on a spectrum analyzer, its out-
of functions in response to a transmitted signal.
put looks like the teeth of a comb. 2. A transmit-
command destruct signal A signal for instigating
ter with many spurious signals at its output.
the destruction of a missile in flight.
combination 1. A functional, usually stationary,
command guidance system A system in which a
installation consisting of two or more pieces of
guided missile and its target are both tracked by
equipment. Examples: transmitter/receiver com-
bination, motor/generator combination, and
command language A computer language made
tuner/amplifier combination. 2. In mathematics,
up of command operators.
a selection of several factors from a group, with-
command link In a command guidance system,
out regard to order. Thus, from the group ABC,
the section that transmits missile-steering com-
the three possible combinations are AB, AC, and
command network A radio communications net-
combinational circuit Two or more basic logic cir-
work in which the chain of command is rigor-
cuits, combined in such a way that the output
ously defined and followed.
state depends entirely on the input states.
command reference The current or voltage to
combination bridge A bridge that affords two or
which a feedback signal is referenced in a control
more classes of measurement, usually select-
system or servomechanism.
able by means of a function switch. Examples:
comment A statement written into a computer
capacitance-inductance bridge, and capacitance-
program for a documentation, rather than imple-
resistance bridge.
mentation (e.g., to describe the purpose of a step
combination cable A cable that has conductors
or subroutine).
grouped in pairs, threes, quads, or similar ar-
comment field A record or file in which instruc-
tions or explanations are given.
combination feedback See CURRENT-VOLTAGE
commercial data processing A commercial
(rather than industrial, scientific, or personal) ap-
combination microphone Two or more micro-
plication of data processing.
phones combined into one unit.
130 commercial-level security • common-mode input capacitance

commercial-level security See LEVEL-2 SECU- common-drain circuit A field-effect transistor cir-
RITY. cuit in which the drain terminal is the common
commercial killer A usually remote-controlled, (or grounded) electrode. Also called grounded-
electronic relay for disabling a radio or television drain circuit and SOURCE FOLLOWER.
receiver during advertisements. common-emitter circuit A bipolar transistor cir-
commercial language A computer programming cuit in which the emitter is the common (or
language for commercial applications (payroll, for grounded) electrode. Also called grounded-emitter
example). circuit.
common 1. Grounded. 2. Pertaining to a connec- common-gate circuit A field-effect transistor cir-
tion shared by several different points in a circuit cuit in which the gate is the common (or grounded)
or system. 3. See COMMON GROUND. electrode. Also called grounded-gate circuit.
common area A computer storage area usable by common-grid circuit A tube circuit in which the
several programs or segments within a program. control grid is the common (or grounded) elec-
common-base circuit A bipolar transistor circuit trode. Also called grounded-grid circuit.
in which the transistor base is the common (or common ground A single ground-point connection
grounded) electrode. Also called grounded-base shared by several portions of a circuit.
circuit. common impedance A single impedance shared
common battery 1. A battery shared by two or by parts of a circuit. Because currents from the
more different circuits or pieces of equipment. 2. various parts flow through this impedance simul-
In wire telephony, a central office battery that taneously, coupling (desired or undesired) can
supplies the entire system. occur between them.
common-battery office In wire telephony, a cen- common-impedance coupling See COMMON-
tral office that provides a common battery. CAPACITOR COUPLING, COMMON-INDUCTOR
common business-oriented language See COBOL. COUPLING, and COMMON-RESISTOR COU-
common-capacitor coupling The process of cou- PLING.
pling one tuned circuit to another by means of a common-inductor coupling The process of cou-
capacitor that is common to both circuits. pling one tuned circuit to another by means of an
inductor that is common to both circuits.
C1 C3
C1 C2
Input L1 (Common L2 Output
capacitor) Input L3 Output
L1 (Common

common-capacitor coupling
common-inductor coupling
common-carrier fixed station A fixed radio sta-
tion that provides public service. common language A language recognized by all
common-cathode circuit A tube circuit in which the equipment in a data processing system.
the cathode is the common (or grounded) elec- common logarithm Abbreviation, log10. Also
trode. Also called grounded-cathode circuit. called base-10 logarithm. A logarithm in which
common-channel interference Radio interference the base number is 10. Also see LOGARITHM.
resulting from two stations transmitting on the common mode Pertaining to signals or signal
same channel. It is characterized principally by components that are identical in amplitude and
beat-note (heterodyne whistle) generation, and duration.
suppression or capture of the weaker signal by common-mode characteristics In an operational
the stronger one. amplifier, characteristics denoting amplifier per-
common-collector circuit A bipolar-transistor formance when a common signal is applied to in-
circuit in which the collector is the common (or verting and noninverting inputs.
grounded) electrode. Also called grounded-collec- common-mode gain The voltage gain of a differen-
tor circuit and EMITTER FOLLOWER. tial amplifier with a common-mode input.
common communications carrier A communica- common-mode impedance input The impedance
tions company authorized by the licensing agency between ground and one of the inputs of a differ-
to furnish public communications. ential amplifier. Compare COMMON-MODE IN-
common-component coupling See COMMON- PUT IMPEDANCE.
CAPACITOR COUPLING, COMMON-INDUCTOR common-mode input capacitance In a differen-
COUPLING, and COMMON-RESISTOR COU- tial amplifier, the internal capacitance of the
PLING. common-mode input circuit.
common-mode input circuit • commutating capacitor

common-mode input circuit In a differential am- common-source circuit A field-effect transistor
plifier, the input circuit between ground and the circuit in which the source terminal is the
inputs connected together. common (or grounded) electrode. Also called
common-mode input impedance In a differential grounded-source circuit.
amplifier, the open-loop impedance between common-user channels Communication channels
ground and the inputs connected together. Com- open to all licensees in a particular service.
pare COMMON-MODE IMPEDANCE INPUT. communication band A band of frequencies
common-mode input signal A signal applied to whose use is authorized expressly for communi-
the common-mode input circuit of a differential cations, rather than for other services (such as
amplifier (i.e., to both inputs connected together). broadcasting, education, remote control, etc.).
Compare COMMON-MODE SIGNAL. communication channel 1. In radio or wire ser-
common-mode input voltage In a differential am- vice, a (usually auxiliary) channel for direct ex-
plifier, the maximum voltage that can be applied change of information between units of the
safely between ground and the inputs connected service (e.g., a “talking circuit” between a broad-
together. cast studio and the transmitter house). 2. A data
common-mode interference A form of interfer- transmission channel between two points (e.g., a
ence that occurs across the terminals of a remote terminal and a central computer system).
grounded system. communication link 1. Collectively, the equip-
common-mode rejection The extent to which a ment providing a communication channel be-
differential amplifier will reject a signal pre- tween two transmitters. 2. Data terminal
sented simultaneously to both inputs in phase, equipment.
or of two signals identical in amplitude, fre- communication protocol The specifications of a
quency, and phase applied separately to the two digital signal, including the speed in bits per sec-
inputs. Also see COMMON-MODE REJECTION ond (bps) or bauds, the code type, the bit dura-
RATIO. tion, the mark-to-space ratio, etc.
common-mode rejection ratio In a differential communications The science and art of using and
amplifier, the extent to which the amplifier can- developing electronic equipment and processes
cels undesired signals. It is the ratio of the differ- for the transmission and reception of informa-
ential gain to the common-mode gain. Also see tion.
COMMON-MODE REJECTION. communications common carrier An organiza-
common-mode signal The algebraic average of tion licensed to provide public communication
two signals applied simultaneously to the two services.
ends of a balanced circuit, such as a differential communications network An organization of
amplifier. Compare COMMON-MODE INPUT SIG- transmitting and receiving stations for the reli-
NAL. able exchange of intelligence. Also called net.
common-mode voltage The part of the input that communications receiver A general-coverage or
is common to both inputs of a differential ampli- multiband radio receiver, designed primarily for
fier circuit. It is quantitatively defined as the listening to amateur, weather, or other non-
arithmetic mean of the voltages at the inputs. broadcast stations. Compare BROADCAST RE-
common-mode voltage gain See COMMON- CEIVER.
MODE GAIN. communications satellites Satellites in earth or-
common-mode voltage range The range limited bit that provide propagation paths (e.g., by reflec-
by the maximum nonsaturating input voltage tion or retransmission) for radio waves between
that can be applied to both inputs of an opera- terrestrial transmitters and receivers. Also see
common pool An assigned memory store, utilized PASSIVE COMMUNICATIONS SATELLITE.
by two or more circuits or systems. community-antenna television Abbreviation,
common-resistor coupling The process of cou- CATV. A system in which an advantageously lo-
pling one circuit to another by means of a resistor cated receiving station receives television signals,
that is common to both circuits. amplifies them if necessary, and distributes them
in the community served by the system. Com-
monly called cable TV.
C1 C2 commutating capacitor 1. In a flip-flop circuit, a
capacitor connected in parallel with the cross-
coupling resistor to accelerate the transition from
R1 one stable state to the other. Also called speedup
Input (Common L2 Output
capacitor. 2. A capacitor connected in parallel be-
tween silicon-controlled rectifier (SCR) stages to
momentarily reverse the current going through
the SCR, thereby causing the SCR to go into the
cutoff condition.
common-resistor coupling
132 commutation • compass

commutation 1. In a direct-current (dc) generator, companding law The mathematical function used
periodic reversal of the current in the armature for companding. It is an output-amplitude versus
coils as the coils alternately pass the north and input-amplitude function for the compression at
south poles of the magnetic field. When the ends the transmitter, and the inverse of this function
of each coil are connected to opposite bars of the for the expansion at the receiver.
commutator, the electrical polarity at the com- companion keyboard An auxiliary keyboard con-
mutator brushes remains constant. 2. In a thyra- nected to a regular keyboard and operated re-
tron or silicon-controlled rectifier (SCR) circuit, motely.
momentarily reversing the polarity to cut the de- companionship machine A computer or robot
vice off. with sufficient machine intelligence to provide en-
commutator 1. In a direct-current (dc) motor, tertainment and mental stimulation for humans.
generator, or rotating selector, an arrangement comparator 1. An integrated circuit (IC) with two
of parallel metal bars or strips on a rotating inputs, called A and B. The device compares the
drum. As the drum turns, the bars contact one voltages that appear at these inputs. If the input
or more brushes that are in sliding contact with voltage at A is significantly greater than the input
the commutator. 2. An electronic circuit that voltage at B, the output is about +5 V. If the in-
switches a single input sequentially to a series of put voltage at A is not greater than the input
output terminals, or switches a number of in- voltage at B, the output voltage is about +2 V.
puts sequentially to a single pair of output ter- These ICs are used to actuate, or trigger, other
minals. devices such as relays and electronic switching
commutator ripple The pulsating voltage super- circuits. 2. In general, any circuit that compares
imposed on the direct-current (dc) voltage deliv- some characteristic of two input signals and pro-
ered by an unfiltered dc generator. duces an output that depends on the relation-
compact disc Abbreviation, CD. A digital, high- ship between the inputs. 3. An instrument for
density optical disc, used in high-fidelity stereo checking the condition of a component by com-
sound systems. Also used to store computer data. paring it directly with an identical component of
The information is encoded as tiny pits on the known quality has a scale reading in percentage
surface of the disc, and is recovered by a laser, a deviation, or simply “GO/NO-GO.” Examples: ca-
sensor and a digital-to-analog (D/A) converter. pacitor comparator, resistor comparator, coil
These disks have largely superseded magnetic comparator.
tapes, and have rendered long-playing vinyl disks compare In computer operations, a relational test
and turntables obsolete. See also COMPACT- performed on two quantities to determine their
DISK READ-ONLY MEMORY. relative magnitude, including an indication of the
compact-disk read-only memory Abbreviation, test result and, sometimes, the taking of action.
CD-ROM. A digital COMPACT DISC used for the Example: the process and acton resulting from
long-term storage of computer data and/or soft- execution of the statement “IF A > B THEN GO TO
ware programs. Usually the same size as a high- LINE 250.”
fidelity stereo disk, it can hold over 600 comparison 1. An expression of the relationship be-
megabytes of data. Although data can be read tween two voltages, currents, phase angles, com-
from the disk, it cannot be overwritten. ponent values, or other quantities in an electrical
compander Term for compressor/expander. In the or electronic circuit or system. 2. An examination
transmission and reception of audio-frequency of different data bits or items, which results in a
(AF) intelligence, a system that uses an amplitude conclusion about some aspect of their relationship.
compressor at the transmitter and an amplitude comparison bridge A bridge designed especially
expander at the receiver. The compressor reduces for the quick comparison of components (e.g., the
the dynamic range before transmission, and the comparison of resistors with a standard resistor,
expander restores it after reception. Provides im- inductors with a standard inductor, and capaci-
proved signal-to-noise ratio under marginal com- tors with a standard capacitor).
munications conditions. Also increases the ratio comparison measurement A measurement in
of average power to peak power. See COMPAND- which a quantity or component is compared with
ING. a known, similar quantity or component value,
companding A process in which a signal is com- rather than having the measurement displayed
pressed at the transmitting end of a circuit and directly by a meter. Examples: bridge measure-
expanded at the receiving end, yielding a signal ments, potentiometric measurements, and fre-
like the original at the receiver output. Signals quency matching.
are more efficiently transmitted when they are compass 1. Any of several instruments for deter-
compressed because the average power in- mining direction on the earth™s surface [e.g., mag-
creases, relative to the peak power. This improves netic (mariner™s) compass and gyrocompass]. 2. A
the average signal-to-noise ratio for weak signals. radio direction finder. 3. An instrument for draw-
See COMPANDER. ing circles.
compatibility • compensation theorem

compensating diode A junction diode used to
compatibility 1. A desirable condition in which
temperature-stabilize a transistor circuit. It is
devices or systems can function efficiently to-
usually forward-biased in the base-bias network
gether, without any modification of equipment. 2.
of the transistor.
In computer operations, a desirable condition in
compensating filter 1. A selective filter used for
which different computers can run the same soft-
the purpose of eliminating some irregularity in
ware, without any modification of hardware or
the frequency distribution of received energy. 2. A
filter used to change the wavelength distribution
compatible color television A color-television
of electromagnetic energy.
system whose transmissions can be received in
compensating resistor 1. A low-value resistor
black and white by any ordinary monochromatic
of known temperature coefficient, connected in
series with a main resistor to reduce the
compatible integrated circuit A hybrid integrated
resistance/temperature drift to zero, or to some
circuit (IC) that has an active element inside the
desired positive or negative value. 2. See TRIM-
integrated structure and a passive element de-
posited on its insulated outer surface.
compensated amplifier A wideband amplifier
whose frequency range is extended by special
components and circuit modifications. Also see
compensated diode detector A diode detector in
which a positive dc voltage from the automatic- Main
gain-control (AGC) rectifier is applied to the diode
anode. The voltage is always proportional to the
signal carrier. The arrangement allows the diode
to handle a heavily modulated AM signal without
producing excessive distortion.
compensated-impurity resistor A resistor con-
sisting of a diffused semiconductor material to
which are added controlled amounts of n- or p-
type dopants (impurities). Comp
compensated-loop direction finder A direction
finder whose loop antenna is complemented by compensating capacitor, 1.
another antenna for polarization-error compen-
compensated semiconductor A doped semicon-
ductor material in which the acceptor impurity
cancels the effects of the donor impurity.
compensated volume control A combination vol-
ume-tone control that provides bass boost at low compensating resistor, 1.
volume levels to compensate for the ear™s defi-
ciency at low frequencies.
compensating capacitor 1. A capacitor that has a compensation Adjusting a quantity, manually or
temperature coefficient of capacitance numerically automatically, to obtain precise values, or to
equal to, but having the opposite sign from, that of counteract undesired variations. Example: tem-
another capacitor in a tank or other circuit. When perature compensation of electronic components.
the capacitors are connected in parallel, a temper- For illustration, see COMPENSATING CAPACI-
ature-induced value change in the main capacitor TOR, 1.
is balanced by an equal and opposite change in compensation coil In a video amplifier, an induc-
the compensating capacitor; the net capacitance of tor connected in series with the collector or drain
the circuit does not change. This greatly reduces resistor, or in the coupling path between stages,
frequency drift. 2. In a video amplifier, a large ca- or both, to boost high-frequency response.
pacitance connected between ground and a tap on compensation filter See COMPENSATING CA-
the collector or drain resistor to boost low- PACITOR, 2.
frequency response. Compare COMPENSATION compensation signal A signal recorded on a tape
COIL. 3. A usually low-capacitance capacitor of track containing computer data, to ensure that
known temperature coefficient, operated in combi- the tape plays back at exactly the correct speed at
nation with a main capacitor to reduce capaci- all times.
tance/temperature drift of the latter to zero or to compensation theorem An impedance (Z ) in a
some desired positive or negative value. network can be replaced by a generator having
134 compensation theorem • complementary wave

zero internal impedance, and whose generated which logic gates are formed by n-channel/
voltage equals the instantaneous potential differ- p-channel pairs of metal-oxide-semiconductor
ence produced across Z by the current flow- field-effect transistors (MOSFETs) fabricated on a
ing through it. Compare MAXIMUM POWER substrate. Noted for high speed and low current
RECIPROCITY THEOREM, SUPERPOSITION complementary operator The logical negation
compensator A device or circuit that facilitates the complementary pushpull circuit See COMPLE-
adjustment of a quantity, manually or automati- MENTARY-SYMMETRY CIRCUIT.
cally, to obtain precise values, or to counteract complementary rectifier In the output circuit of a
undesired variations. magnetic amplifier, nonsaturating half-wave rec-
compilation time The period during which a pro- tifier elements.
gram is compiled, as distinct from RUN TIME. complementary silicon-controlled rectifier A
compile 1. To unify computer subroutines into an silicon-controlled rectifier that has polarity
all-encompassing program. 2. To gather infor- opposite from the usual silicon-controlled recti-
mation or data together into a single file or file fier.
set. complementary-symmetry circuit A bipolar-
compiler In computer operations, a program that transistor circuit that uses an npn and pnp tran-
changes a HIGH-LEVEL LANGUAGE, such as sistor. The transistors conduct during opposite
BASIC, C, C++, COBOL, or FORTRAN, into MA- half-cycles of the input signal, the result being
CHINE LANGUAGE. A compiler must be written that push-pull output is provided with a single-
especially for the high-level language being used. ended input; no phase-splitting input circuit is
compiler language Any computer language that required. The complementary-symmetry circuit
serves as an interface between the operator and offers very low output impedance, permitting a
the computer. loudspeaker voice coil (or other low-impedance
compiler program A program that converts com- load) to be operated directly without a coupling
piler language into machine language. transformer.
compiling routine In digital computer operation, a
routine permitting the computer itself to con-
struct a program to solve a problem.
complement 1. The difference between a number
and the radix (modulus or base) of the number
system. For example, the complement of 7 is
equal to 3 (because 10 “ 7 = 3) in the decimal
(radix-10) number system. 2. Also called ones +
complement. In computer operations, a repre-
sentation of the negative value of a binary num-
ber. All the available digits are set to 1, and then
the number in question is subtracted. For ex-
ample, the complement of 101 is equal to 010
(because 111 “ 101 “ 010); the complement of
1001 is equal to 0110 (because 1111 “ 1001 =
complementary A Boolean operation whose result
is the same as that of another operation, but with
the opposite sign; thus, OR and NOR operations
are complementary.

complementary colors 1. In the additive color
system, two colors that produce light gray or
complementary-symmetry circuit
white when combined. 2. In the subtractive
color system, two pigments that produce dark
gray or black when combined. 3. Colors or pig- complementary tracking A control system in
ments that are opposite each other on the color which several secondary (slave) devices are con-
wheel. trolled by a primary (master) device.
complementary constant-current logic A form of complementary transistors A transistor pair of
bipolar logic with high operating speed and high opposite polarity operated in a complementary-
component density. symmetry circuit or its equivalent.
complementary metal-oxide semiconductor complementary wave An electromagnetic wave in
Also sometimes called complementary metal-oxide a transmission line that occurs as a result of re-
silicon. Acronym, CMOS (pronounced “seamoss”). flection. Any impedance discontinuity will result
A digital integrated-circuit (IC) technology, in in complementary waves.
complementer • component

complementer A logic circuit that provides an out- complex permeability An expression of inductor-
put pulse when there is no input pulse, and vice core permeability, obtained from the mathemati-
versa. Also called INVERTER and NOT CIRCUIT. cal ratio of the magnitudes of the vectors
complement number In a base-n number system, representing the induction and electromagnetic
for a given positive integer p less than n, the posi- field strength within the core.
tive integer m such that m + p = n. For example, in complex plane A Cartesian coordinate system
the decimal (base-10) system, the complement of 4 with real numbers on the horizontal axis and
is 6, the complement of 7 is 3, and the complement imaginary numbers on the vertical axis. Used for
of 9 is 1. In the hexadecimal (base-16) number vectorial representation of complex numbers. See
system, the complement of 4 is 12, the comple- ARGAND DIAGRAM.
ment of 7 is 9, and the complement of 9 is 7. complex quantity A quantity containing both real
complement-number handling A computer sys- and imaginary components. Example: Im-
tem in which the operations are carried out via pedance (Z ) is a complex combination of resis-
the complements of the input numbers. tance R (a real component) and reactance jX (an
complement-setting technique A process of de- imaginary component): Z = R + jX.
termining the number of pulses required to com- complex radar target A radar target that is large
plete the switching of a counter circuit when it is enough in theory to be detected by radar, but, be-
started at some state higher than full zero. The cause of its geometry, cannot be detected. This ef-
number of pulses required for completion is equal fect is the result of phase combinations of signal
to the number that represents the starting state™s components reflected from various surfaces on
complement. the target.
complete carry In digital computer operation, a complex series permeability An expression of
system permitting all carries to generate carries. complex permeability of an inductor core under
complete circuit See CONTINUOUS CIRCUIT. actual operating conditions, assuming zero loss
complete modulation Modulation to the maxi- in the conductors of the coil winding. A series
mum extent possible while maintaining accept- combination of reactance and resistance.
able circuit or system operation. complex steady-state vibration Periodic vibration
complete operation In computer operations, the with more than one sine-wave component.
condition in which the machine rigorously follows complex tone An audio tone made up of more
program instructions. than one sine-wave component.
complete routine A vendor-supplied computer complex variable A variable having real and imag-
program that is usable without modification. inary parts.
complex function 1. A mathematical function of a complex waveform The shape of a COMPLEX
complex-number variable. 2. An integrated cir- PERIODIC WAVE. It is the resultant of the indi-
cuit (IC) containing two or more subcircuits that vidual sine-wave components (i.e., of the funda-
perform an operation more complicated that of mental and the harmonics).
any one of the circuits alone. complex-wave generator A signal generator
complex notation Notation taking into considera- whose output signal is any of several selectable
tion both the real-number and imaginary-num- waveforms and frequencies (or repetition rates).
ber components of a quantity. Thus, impedance Also see FUNCTION GENERATOR.
(Z ) is a complex quantity that includes a resistive compliance 1. The ease with which a material can
(real) component (R) and a reactive (imaginary) be flexed or bent, an important characteristic of
component ( j X ). See COMPLEX NUMBER and transducers (such as loudspeakers). Expressed
COMPLEX OPERATOR. in cm/dyne, compliance is the reciprocal of stiff-
complex number A number expressed in complex ness, and is the acoustical or mechanical equiva-
notation (e.g., a + jb, where a and b are real num- lent of capacitance. 2. A measure of the output
bers and j is the COMPLEX OPERATOR). Can impedance of a switched-current signal source.
also be expressed as a point or a vector in an AR- Generally given as maximum current for a certain
GAND DIAGRAM. change in the voltage.
complex operator The unit imaginary number, compliance range The voltage range required to
represented as j by engineers and as i by mathe- maintain a constant current throughout a load-
maticians. This number is defined mathemati- resistance range.
cally as the positive square root of “1. compliance voltage The range over which the out-
complex parallel permeability An expression of put voltage of a constant-current power supply
the permeability of an inductor core under actual must swing in order to maintain a steady current
operating conditions, assuming zero loss in the in a varying load.
conductors of the coil winding. A parallel combi- compliance-voltage range The output voltage
nation of reactance and resistance. range of a constant-current power supply.
complex periodic wave A periodic wave composed component 1. A device or part used in a circuit to
of a sine-wave fundamental and certain harmon- obtain some desired electrical action [e.g., a resis-
ics in specific proportions. tor (passive component) or an integrated circuit
136 component • compress

(active component)]. Also see ACTIVE COMPO- composition resistor A resistor made from a mix-
NENT and PASSIVE COMPONENT. 2. An at- ture of materials, usually finely powdered carbon
tribute inherent in a device, circuit, or and a binder.
performance (e.g., the REACTIVE COMPONENT compound A substance in which the atoms of two
of an inductor). 3. A specified quantity or term or more elements have united chemically to form
(e.g., the WATTLESS COMPONENT of ac power). a molecule. For example, an atom of cadmium
4. A piece of equipment in a high-fidelity sound (Cd) and one of sulfur (S) combine to form a
system. molecule of cadmium sulfide (CdS).
component density The number of components compound connection A direct connection of two
(see COMPONENT, 1) in an electronic assembly of transistors, the amplified output of the first being
a given physical volume. further amplified by the second. The connection
component failure rate 1. The percentage of provides extremely high current gain. Also called
components, out of a specified group, that can DARLINGTON PAIR.
be expected to fail within a specified length of compound generator A generator that has both
time. 2. The frequency with which a given com- series and shunt fields. Also called compound-
ponent, in a certain application, can be expected wound generator.
to fail. compound horn A horn reflector used for trans-
component layout The mechanical arrangement mission of microwave energy. The faces of the

of components (see COMPONENT, 1) in an elec- horn approach four geometric plane surfaces as
tronic assembly. the distance from the center increases.

component stress The electrical or mechanical compound modulation A system of successive
strain to which a component is subjected. In gen- modulation, the modulated wave from one step
eral, the greater the stress, the higher the compo- becoming the modulating wave in the next. Also
nent failure rate. called multiple modulation.
composite cable A cable containing other cables of
different types.
composite circuit A circuit handling telegraphy
and telephony simultaneously without causing
mutual interference.

composite color A color that is not one of the PA
COLOR PRIMARIES, but instead, consists of a
combination of the three color primaries.
composite color signal The complete color televi-
Data Mod Mod Mod
sion signal, including all picture, color, and con- Amp
in #1 #2 #3
trol components.
composite conductor A set of wires connected in
parallel. The wires are often, but not necessarily,
of identical size and constitution. Osc Osc Osc
composite current A current having both alter- #1 #2 #3
nating-current (ac) and direct-current (dc) com-
ponents; an alternating current superimposed on
compound modulation
a direct current. Also called fluctuating current.
composite curve A curve or pair of curves showing
two modes of operation, as of biased and unbi- compound motor An electric motor having both
ased conditions. series and shunt fields. Also called compound-
composite filter A filter consisting of more than wound motor.
one section. The sections might be, but often are compound transistor Two or more transistors di-
not, identical. rectly coupled in the same envelope for increased
composite video signal The television picture sig- amplification. Also see COMPOUND CONNEC-
nal containing picture information and sync TION.
pulses. compound-wound generator See COMPOUND
composite-video-signal distortion Distortion of GENERATOR.
the composite video signal as evidenced by over- compound-wound motor See COMPOUND MO-
shooting, ringing, and sync-pulse shortening. TOR.
composite voltage A voltage having both alternat- compress 1. In communications, to reduce or min-
ing-current (ac) and direct-current (dc) compo- imize the bandwidth of a signal. 2. In communi-
nents; an ac voltage superimposed on a dc cations, the processing of a signal to increase
voltage. Also called fluctuating voltage. low-level components and thereby raise the aver-
composite wave filter Two or more wave filters age power level relative to the peak power level. 3.
(not necessarily of the same type) operated in cas- In computer operations, to reduce or minimize
cade. the number of bits in a digital signal or file, while

compress • computer graphics

still retaining all the essential information. Com- Compton diffusion An effect that occurs when a
pare EXPAND. photon and electron collide. Some of the energy
compressed-air capacitor A high voltage air- from the photon is transferred to the electron. On
dielectric capacitor enclosed in a case in which a large scale, such collisions result in diffusion of
the air pressure is held at several atmospheres. electromagnetic waves.
The device exploits the dielectric strength of com- Compton effect The increase in wavelength (de-
pressed air, which is higher than that of air at crease in frequency) of X-rays scattered by the
normal pressure. electrons of lighter atoms bombarded with the
compressed-air speaker A speaker that uses an X-rays.
airtight chamber to enhance the acoustic repro- Compton shift See COMPTON EFFECT.
duction at certain frequencies. compute To perform a mathematical operation by
compression 1. In communications, the reduction means of a relatively simple process. Thus, a dig-
or minimization of signal bandwidth. 2. In com- ital computer solves intricate problems using
munications, the processing of a signal to in- simple arithmetic steps. Compare CALCULATE.
crease low-level components and thereby raise computer A device or machine for performing
the average power level relative to the peak power mathematical operations on data, and producing
level. Usually, a logarithmic function. 3. In com- the results as information or control signals.
puter operations, the reduction or minimization There are numerous types, the most common be-
of the number of bits in a digital signal or file, ing the digital computer.
while still retaining all the essential information. computer-aided design Abbreviation, CAD. The
Compare EXPANSION. use of computers in conceiving, developing, and
compression ratio In a system using COMPRES- perfecting new products.
SION, the ratio A1/A2, where A1 is the gain (or computer-aided manufacturing Abbreviation,
transmission) at a reference-signal level and A2 is CAM. The use of automated manufacturing sys-
the gain (or transmission) at a specified higher tems, such as assembly lines, that are partially or
signal level. totally controlled by computers.
compression wave A wave disturbance that trav- computer antibody Also called vaccine. A small
els via longitudinal motion of particles in a subprogram designed to eliminate viruses from
medium. Sound waves through air are the most computer systems.
common example. computer-assisted instruction Abbreviation, CAI.
The use of computers as teaching and training
computer code See MACHINE LANGUAGE.
computer consciousness The degree to which a
machine can be considered aware of its own exis-
tence. Until recently, this idea was considered
ridiculous. But as microprocessor power contin-
ues to grow, some researchers now consider it
worth thinking about.
computer-controlled catalytic converter A mi-
croprocessor-controlled system for automatically
supervising gaseous emissions exhausted by a
motor vehicle. An oxygen sensor monitors the ex-
haust stream, and the associated electronic sys-
tem adjusts the air-to-fuel ratio of the carburetor
to reduce smog-producing pollutants in the ex-
computer diode A semiconductor diode having
low capacitance and fast RECOVERY TIME, thus
suiting it to rapid switching in computer circuits
and to very-high-frequency applications.
computer engineer A person skilled in the theory
and application of computers, related equipment,
and associated mathematics.
computer file See FILE.
compressor A circuit or device that limits the am-
computer game See VIDEO GAME.
plitude of its output signal to a predetermined
computer graphics 1. The use of computers to
value, despite wide variations in input signal am-
assist in drawing and drafting, and in the pro-
cessing of video images such as photographs.
compressor driver unit A loudspeaker that works
2. Broadly, any computer-generated or computer-
into an air space connected by a throat to a horn,
processed image.
rather than by driving a diaphragm.
138 computer instruction • condenser microphone

computer instruction See INSTRUCTION. operated with their shafts coupled together. The
computer interfacing apparatus The equipment stator of the first motor is connected to the 3-
used to connect a computer to other systems, phase supply, and the slip rings of this motor are
and to peripherals. connected to the field of the second motor. The
computerized axial tomography Abbreviation, slip rings of the second motor are connected to
CAT. A multiple X-ray system that enables the the three ganged sections of a Y-rheostat used for
observer to obtain cross-sectional images of the adjusting the speed. 2. Arrangement of a set into
internal organs of the body. a series.
computer map A blueprint, used in conjunction concentrated-arc lamp A brilliant low-voltage
with machine vision, sonar, radar or beacons, lamp, containing nonvaporizing electrodes in an
that a mobile robot can use as a navigational aid. inert-gas atmosphere. An arc across the elec-
One or more such blueprints are stored in the trodes creates the light source.
robot controller™s main memory. concentrated winding A coil winding that has a
computer music 1. Music that is composed by a large number of turns in a small space.
computer. 2. See MUSICAL INSTRUMENT DIGI- concentration cell An electrolytic cell in which
TAL INTERFACE. two electrodes are immersed in solutions of the
computer program See PROGRAM. same compound but having different combina-
computer programmer A person skilled in devis- tions. The voltage is usually very small, 0.1 volt or
ing and/or writing the routines that a digital less.
computer uses to solve problems or process data. concentration gradient Between points in a semi-
computer storage tube A cathode-ray tube in conductor, the difference in electron or hole con-
which the electron beam scans and stores infor- centration.
mation in thousands of memory cells on a target. concentric cable See COAXIAL CABLE.
A cell “remembers” by acquiring and holding an concentric capacitor A fixed or variable capacitor
electrostatic charge when it is struck by the beam whose plates are concentric cylinders. Also called
from the writing gun. Information taken is read concentric-plate capacitor.
out of a cell by a second beam from the reading concentric jack See COAXIAL JACK.
gun. concentric line See COAXIAL LINE.
computer system A central processor and its as- concentric-line oscillator A stable, self-excited
sociated online and offline peripherals, such as a oscillator whose frequency-determining tank con-
monitor, modem, printer, optical scanner, mag- sists principally of a section of concentric (coax-
netic disk drives, CD-ROM drive, and tape ial) line. Used primarily at ultra-high frequencies
backup. (UHF).
computer technician A professional skilled in concentric plug See COAXIAL PLUG.
building, repairing, and maintaining computers, concentric receptacle See COAXIAL RECEPTA-
and who, occasionally, designs them. Usually CLE.
works under the supervision of a computer engi- concentric tank See COAXIAL TANK.
neer. concentric-wound coil A combination of two or
computer terminal 1. A teleprinter or video dis- more coils wound on top of, and insulated from,
play unit and keyboard, used by human opera- each other.
tor(s) of a computer. 2. An interface between a conceptual modeling A technique for solving
computer and its human operator(s). problems by devising a mathematical model
computer/TV interface A device or circuit for de- based on the results of an experiment; experi-
livering the output of a digital computer to a stan- ments performed on the model are used to verify
dard television receiver so that the latter can its validity.
serve as a GRAPHIC TERMINAL. concurrent conversion In computer operations,
computer virus A deliberately created and dissem- running conversion and conventional programs
inated subprogram or piece of programming code, together. Also see CONVERSION PROGRAM.
that electronically spreads through computer concurrent processing See MULTIPROGRAM-
systems and hinders operation. Usually diverts MING.
the computer(s) from intended functions; some- condenser 1. An obsolete term for CAPACITOR. 2.
times causes a catastrophic malfunction. Often A mirror or lens for concentrating light (on an ob-
exists undetected, being transferred from one ject, for example). 3. Something that condenses a
computer to another by means of diskettes or gas or vapor. 4. See CONDENSER MICRO-
software. PHONE.
computer word See WORD. condenser antenna A two-wire horizontal antenna
computing amplifier See OPERATIONAL AMPLI- system in which the radiator is a wire situated
FIER. above a counterpoise.
computing machine See COMPUTER. condenser microphone Also called capacitor mi-
concatenation 1. A method of speed control for a crophone. A microphone in which a tightly
3-phase motor in which two induction motors are stretched metal diaphragm forms one plate of an
condenser microphone • conductor

conducted heat Heat transferred by conduction
1/2 -Wave
through a material substance, as opposed to con-
vection and radiation. A heatsink conducts dissi-
pated energy away from a transistor, whereupon
Feed line
convection and radiation allow heat to escape
from the sink.
conduction 1. The propagation of energy through
Counterpoise a medium, depending on the medium for its
travel. 2. The transfer of electrons through a wire.
condenser antenna 3. The transfer of holes through a P-type semi-
conductor material. 4. Heat transfer through a
material object (see CONDUCTED HEAT).
air capacitor, and a closely situated metal plug
conduction angle See ANGLE OF CONDUCTION.
forms the other plate. A dc bias voltage is applied
conduction band In the arrangement of energy
to the arrangement. Impinging sound waves
levels within an atom, the band in which a free
cause the diaphragm to vibrate, varying the ca-
electron can exist; it is above the valence band in
pacitance and causing the output current to fluc-
which electrons are bound to the atom. In a
tuate accordingly.
metallic atom, conduction and valence bands
condensing routine In computer operations, a
overlap; but in semiconductors and insulators,
program that compresses data. See COMPRES-
they are separated by an energy gap.
SION, 3.
conduction current 1. The electromagnetic-field
condensite A plastic insulating material whose
flow that occurs in the direction of propagation. A
base is phenol formaldehyde resin.
measure of the ease with which the field is prop-
conditional Pertaining to a quantity or phe-
agated. 2. Current in a wire or other conductor.
nomenon that depends on some external factor,
conduction-current modulation In a microwave
and is therefore subject to change.
tube, cyclic variations in the conduction current;
conditional branch A point in a computer pro-
also, the method of producing such modulation.
gram where a relational test is performed, and
conduction electron See FREE ELECTRON.
the statement line in which the test is made is left
conduction error In a temperature-acutated
so that an out-of-sequence instruction can be im-
transducer, error caused by conduction of heat
plemented. Such a branch might be made, for ex-
between the sensor and the mounting.
ample, following a statement, such as “IF Z = Y
conduction field An energy field that exists in the
vicinity of an electric current.
conditional branch instruction The instruction
conductive coating A conducting layer applied to
in a computer program that causes a CONDI-
the glass envelope of a cathode-ray tube, such as
an oscilloscope tube or picture tube.
conditional implication operation A Boolean op-
conductive coupling See DIRECT COUPLING.
eration in which the result of operand values X
conductive material See CONDUCTOR.
and Y are such that the output is high only if in-
conductive pattern The pattern of conductive
put X is high and input Y is low. Also called inclu-
lines and areas in a printed circuit.
sion or if-then operation.
conductivity Unit, S/m (siemens per meter). An
conditional jump See CONDITIONAL BRANCH.
expression of conductance per unit length of a
conditional stop instruction In a computer pro-
material; the reciprocal of resistivity.
gram, an instruction that can cause a halt in the
conductivity meter A device for measuring elec-
run, as dictated by some specified condition.
trical conductivity. Generally, such a device is
conditional transfer See CONDITIONAL BRANCH.
calibrated in siemens.
condition code A set of constraints for a computer
conductivity modulation In a semiconductor, the
program; sets limits on what can be done with the
variation in conductivity that results from a vari-
computer under certain circumstances.
ation of charge-carrier density.
conditioning 1. The process of making equipment
conductivity-modulation transistor A transistor
compatible for use with other equipment. Gener-
in which the bulk resistivity of the semiconductor
ally involves some design or installation changes.
material is modulated by minority carriers.
2. Interfacing.
conductor 1. A material that allows charge carri-
Condor A continuous-wave navigational system
ers (usually electrons) to move with ease among
that produces a cathode-ray-tube display for au-
atoms. Examples are metals, electrolytes, and
tomatically determining the bearing and distance
ionized gases. Substances vary widely in their
from a ground station.
suitability as conductors; the conductivity of
conductance Symbol, G. Unit, siemens. The ability
commercial copper, for example, is almost twice
of a circuit, conductor, or device to conduct elec-
that of aluminum. Compare INSULATOR. 2. An
tricity. Conductance in siemens is the reciprocal
individual conducting wire in a cable, insulated
of resistance: G = 1/R, where R is the resistance
or uninsulated.
in ohms.
140 conduit • conic sections

conduit A hollow tube, made of plastic or metal, confidence level See CONFIDENCE FACTOR.
through which wires, cables, and other transmis- confidence limitations The maximum and mini-
sion media are fed. mum points of a confidence interval. Outside the
cone The conical diaphragm of a (usually dynamic) confidence-limitation points, the confidence fac-
loudspeaker. tor drops below the required minimum.
cone antenna An antenna in which the radiator is configuration 1. The characteristic arrangement
a sheet-metal cone or a conical arrangement of of components in an electronic assembly, or of
rods or wires. the equipment symbols in the corresponding cir-
Conelrad An early amplitude-modulation (AM) cuit diagram. 2. Computer system.
broadcast protocol, intended for use in the event configuration state In a computer system, an ex-
of a nuclear war. Now replaced by the EMER- pression of the availability status of a device for a
GENCY BROADCAST SYSTEM. given application. A configured-in device is avail-
cone marker A UHF marker beacon whose conical able; a configured-out device is available, but is
energy lobe radiates vertically from a radio-range restricted to certain users; a configured-off device
beacon station. Aircraft in flight use such mark- is unavailable.
ers to accurately locate the beacon station. configuration table Within a computer™s operating
cone of protection The zone surrounding a light- system, a table that provides the configuration
ning rod, in which the chances of a lightning state for various system units.
strike are greatly reduced. The cone has an apex configured-in See CONFIGURATION STATE.
angle of 45°, relative to the rod. Objects entirely configured-off See CONFIGURATION STATE.
within this cone are unlikely to be struck (al- configured-out See CONFIGURATION STATE.
though it is still possible). conformance The degree to which a quantity or
variable corresponds to a standard or to expecta-
conformance error The extent (usually expressed
as a percentage) to which conformance is lacking.
conical antenna See CONE ANTENNA.
conical horn A horn (antenna, loudspeaker, or
45° 45°
sound pickup) having the general shape of a
cone: the cross-sectional area varies directly as
the square of the horn™s axial length.
conical monopole antenna An unbalanced broad-
band antenna that derives its name from its
shape. It is usually constructed from wire and
must be operated against a good radio-frequency
(RF) ground.

protected Antenna
region conductor
cone of protection Cross
cone of silence A small zero-signal zone directly
over a low-frequency radio-range beacon. The
zone is the product of the combined directive
properties of the beacon transmitting antenna
and the antenna on an aircraft. Feed point
cone speaker A loudspeaker having a sound-
producing cone (diaphragm) made of specially
treated paper or other material, as opposed to a
loudspeaker having a flat diaphragm.
confetti On a color TV screen, color spots caused
by chrominance-amplifier noise.
conical monopole antenna
confidence The probability that a predicted result
will occur.
confidence factor Confidence, expressed either as conical scanning In radar transmission, a method
a fraction (between 0 and 1) or as a percentage. of scanning in which the beam describes a cone,
confidence interval The range over which a pa- at the apex of which is the antenna.
rameter can vary so that a given confidence factor conic sections The geometric plane figures that
is maintained. result from the intersection of a cone with a
conic sections • constant-current source

plane. These figures are the circle, the ellipse, the program, data items that remain unchanged for
parabola, and the hyperbola. each run.
conjugate For a given complex number A + jB, the constant-amplitude recording In sound record-
quantity A “ jB. When complex conjugates are ing, the technique of holding the maximum am-
multiplied together, the result is A2 + B2. plitude of the signal steady as the frequency
conjugate branches In a network, two branches of changes.
such a nature that a signal in one has no effect on constantan An alloy of copper and nickel used in
the other. some thermocouples and standard resistors.
conjugate bridge A bridge in which the detector constantan-platinum thermocouple A thermo-
and generator occupy positions opposite to those couple that uses the junction between constan-
in a conventional bridge of the same general type. tan and platinum wires, which is contained in
conjugate impedance For a given complex im- thermocouple-type meters.
pedance, R + jX, where R is the resistive compo- constant area As allocated by a computer pro-
nent and jX is the reactive component, the gram, an area of memory that holds constants.
impedance: R “ jX. The resistance is identical; the constant bandwidth In a broadband tuned cir-
reactance is of equal magnitude, but opposite cuit, bandwidth that does not change with fre-
sign (capacitive as opposed to inductive, or vice quency.
versa). constant current A current that undergoes no
conjunction The logical AND operation. change in value as it flows through a changing re-
connect To provide an electrical path between two sistance. Compare CONSTANT VOLTAGE.
points. constant-current characteristic A condition in
connection The point at which two conductors are which the current through a circuit remains con-
physically joined. stant”even if the voltage across the circuit in-
connective An operation symbol written between creases or decreases.
operands. constant-current curve A graph in which the de-
connector 1. A device that provides electrical con- pendent variable is an electric current that levels
nection. 2. A fixture (either male or female) at- off at, or approaches, a specific maximum. An ex-
tached to a cable or chassis for quickly making ample is the collector-current versus collector-
and breaking one or more circuits. 3. A symbol voltage curve for a bipolar transistor.
that connects points on a flowchart.
conoscope A device that uses focused polarized Max.
light to examine crystals (as in checking the opti-
cal axis of a quartz crystal).
consequent poles The poles of an equivalent sin-
gle magnet that is formed when two magnets are
Collector current

aligned with their two identical poles together.
Thus, when the two north poles are placed to-
current region
gether, the consequent poles are a south pole at
each end and a north pole at the center.
conservation of energy 1. The preservation of
the potential for work by a given quantity of en-
ergy”even when it undergoes a change in form
within a system. 2. The law of conservation of
energy, which states that energy can be neither
created nor destroyed, but only changed in
Collector voltage +10 V
console 1. The main station or position for the
constant-current curve
control of electronic and/or computer equipment.
2. The equipment at a fixed location. 3. An equip-
ment-containing cabinet that stands on the floor. constant-current drive Driving power obtained
4. Equipment permitting communication with a from a constant-current source.
computer. Also called dumb terminal. constant-current modulation See CHOKE-
consonance 1. Harmony between audio tones. 2. COUPLED MODULATION.
Acoustical or electrical resonance between bodies constant-current power supply See CONSTANT-
or circuits that are not physically connected. CURRENT SOURCE.
constant 1. A quantity whose value remains constant-current sink See CURRENT SINK.
fixed, such as the speed of light in a vacuum. constant-current source A power supply whose
Compare VARIABLE. 2. The value of a compo- current remains steady during variations in
nent specified for use in a particular electronic load resistance. Also called constant-current
circuit. 3. An electronic component, particularly supply and current-regulated supply. Compare
a capacitance or inductance. 4. In a computer CONSTANT-VOLTAGE SOURCE.
142 constant-current supply • contactor noise

constant-current supply See CONSTANT- contact arc The arc that initially occurs when
CURRENT SOURCE. current-carrying contacts are separated.
constant-current transformer A transformer sup- contact area 1. The face of an electrical contact.
plied from a constant-voltage source that auto- 2. The common area shared by two conductors in
matically delivers a constant current to a varying mutual contact.
secondary load. contact bounce The springing apart or vibration of
constant-k filter Also called a Zobel filter. A filter contacts upon making or breaking.
section in which Z1Z2 equals k2 at all frequencies, contact chatter The abnormal vibration of mating
where Z1 is the impedance of the series element contacts, caused by contact bounce or by an ex-
and Z2 is the impedance of the shunt element. traneous alternating current.
constant-power dissipation line A line connect- contact-closure input The input circuit of a de-
ing points on a family of current-voltage charac- vice, such as a control-system amplifier, that is
teristic curves, the points corresponding to the actuated by the closing of switching contacts.
maximum power that can safely be dissipated by Compare CONTACT-OPEN INPUT.
the device to which the curves apply. contact combination The set of contacts on a
constant-resistance network A circuit of resistors switch or electronic relay.
that, when terminated in a resistance load, pre- contact detector A rectifier or demodulator, com-
sents a constant resistance to a driving source posed of two dissimilar materials in contact with
under various conditions of operation. each other. Semiconductor diodes are of this gen-
constant-speed motor 1. Also called a shunt mo- eral type. Some contact-detector action can be
tor. A motor whose speed varies little, or not at all, obtained with two dissimilar fine wires (such as
with variations in the armature current. 2. A mo- copper and iron) by touching their tips lightly to-
tor that runs at an unvarying speed through the gether.
action of associated automatic electronic control contact EMF Short for contact electromotive force;
circuitry. also called contact potential. A low direct-current
constant voltage A voltage that does not change (dc) voltage that is sometimes generated by the
as the load resistance varies. Compare CON- contact of two dissimilar materials.
STANT CURRENT. contact follow The tendency of relay contacts to
constant-voltage, constant-current supply A follow the actuating signals.
combination current-regulated and voltage- contact force 1. The force with which relay con-
regulated power supply; delivers constant cur- tacts close with a given amount of coil current. 2.
rent to low load resistances and constant voltage The force with which a pair of relay contacts are
to high load resistances. held together when current flows through the
constant-voltage drive Driving power obtained coil. 3. In a mercury-wetted relay, the force ex-
from a CONSTANT-VOLTAGE SOURCE. erted by the mercury on the contacts as the relay
constant-voltage source A power supply whose closes.
output voltage remains steady during variations contact gap The distance between contacts when
in load current. Also called constant-voltage sup- they are open.
ply and voltage-regulated supply. contact load 1. The power dissipated by a load
constant-voltage transformer A special trans- that is connected to a power supply through a
former used to reduce variations in power-line closed set of contacts. 2. The current passing
voltage. A capacitor in the device causes a winding through a set of closed contacts.
to resonate at the line frequency (e.g., 60 Hz). This contact microphone A microphone placed in di-
tends to maintain a more constant current than rect contact with a vibrating surface for pickup.
would be the case in an ordinary transformer. Actuated by the vibration of a solid, rather than
construct A source (user™s) computer program by the movement of air molecules.
statement that, when implemented, produces a contact miss 1. The improper alignment of con-
predetermined effect. tacts in a switch or relay. 2. The condition of re-
consumer reliability risk 1. The chance a con- lay contacts not lining up properly.
sumer takes when buying a component or piece contact modulator An electromechanical CHOP-
of equipment that has not been subjected to PER.
quality-assurance/quality-control (QA/QC) test- contact-open input The input circuit of a device,
ing. 2. An expression of the failure rate for a con- such as a control-system amplifier, that is actu-
sumer item. ated by the opening of switching contacts. Com-
contact 1. A conducting body (such as a button, pare CONTACT-CLOSURE INPUT.
disk, or blade) that serves to close an electric cir- contactor A switch used for frequent opening or
cuit when pressed against another conductor. closing of a circuit. An example is a relay contac-
Example: switch contact and spring contact. 2. tor used for keying a transmitter.
The state of being touched together, as when two contactor noise 1. Electrical noise that is the
conductors are brought into contact to close a product of make-and-break contact action or
circuit. fluctuations in conduction when the contacts are
contactor noise • Continuous Commercial Service

Diaphragm contact wetting The use of mercury (a conducting
liquid) to improve the action of a relay contact or
Movable contacts.
magnet contact wipe A sliding motion between closed con-
Fixed coil
tacts. Helps to establish a good connection and to
keep the contact surfaces clean.
container file See CONTROLLING FILE.
contaminated material 1. A semiconductor mate-
rial containing some undesired substance. 2. A
material unintentionally made radioactive.
contamination 1. The presence of an impurity in a
substance. 2. The addition of a radioactive mate-
rial to a substance. 3. In a coaxial cable, the ten-
dency for the jacket material to bleed through the
outer braid into the dielectric, resulting in in-
creased loss.
content-addressed storage In a computer, mem-
ory- or data-storage locations identified by con-
tent (see CONTENTS), instead of by address. Also
called associative storage.
contention The result of interference among more
than one transmitting station on the same com-
munications channel.
Output contents 1. The data in a computer random-
access memory (RAM). 2. The data in a specific
storage location, such as on a hard disk, diskette,
or CD-ROM.
Object carrying context 1. The environment in which a word is
sound disturbance
used in a natural language (such as English,
Spanish, or Russian). Important in speech
contact microphone
recognition and speech synthesis. 2. The envi-
ronment in which a string of characters, com-
posing a data unit or word, is used in a
closed. 2. Sounds coming directly from contacts
computer program.
that are opening and closing.
Continental code A version of the Morse code
contact potential The small direct-current (dc)
used internationally in radiotelegraphy. Also
voltage that results from the bombardment of an
called International Morse code and general ser-
electrode by electrons, when the electrode has no
vice code. Compare AMERICAN MORSE CODE.
external voltage applied to it.
continuity A condition of being uninterrupted”
contact pressure The pressure that holds con-
especially pertaining to current flowing in an
tacts together.
electrical or electronic circuit.
contact protector A component (such as a diode,
continuity test A test of the completeness of an
capacitor, resistor, or combination of these) that
electrical path. Ideally, the only concern is
serves to suppress contact arcing.
whether the circuit is open or closed, but some-
contact rating The maximum current, voltage,
times circuit resistance is also of interest.
and/or power specified for a given set of contacts.
continuity tester A device (such as an ohmmeter,
contact rectifier A rectifier consisting of two dis-
battery and buzzer, and battery and lamp) with
similar materials in direct contact. Examples:
which a continuity test can be made.
copper and copper oxide, magnesium and copper
continuity writer The person who prepares copy
sulfide, selenium and aluminum, and germa-
for a radio or television broadcaster.
nium and indium.
continuous carrier A medium (such as a radio-
contact resistance The resistance of the closed
frequency wave) that will convey information (as
contacts of switches, relays, and other similar de-
when the carrier is modulated) with no disruption
vices. Normally, this is a very small resistance.
of the medium itself.
contact separation See CONTACT GAP.
continuous circuit An uninterrupted circuit.
contact strip See TERMINAL STRIP.
Continuous Commercial Service Abbreviation,
contact switch An electromechanical switch that
CCS. A category in which safe operating parame-
uses contacts to make and break a circuit, as
ters are listed for electronic components and
compared with an electronic switch that uses
communications equipment operated over long,
semiconductor devices.
uninterrupted periods. Compare INTERMITTENT
contact travel The distance over which a relay or
switch contact must move to close a circuit.
144 continuous duty • contrast

Character Symbol continuous duty The requirement of a device to
sustain a 100-percent duty cycle for a prolonged
A •“
period of time.
B “••• continuous-duty rating A maximum current, volt-
C “ •“ • age, or power rating for equipment operated for
D “ •• extended periods at a 100-percent duty cycle.
E •
continuous load A load that requires a continuous
F ••“ •
feed for a prolonged period of time.
G ““• continuous memory See NONVOLATILE MEM-
H ••••
I ••
continuous-path motion In robotics, machine
J •“““
movement that occurs in a smooth fashion,
K “ •“ rather than in discrete steps. Allows precise posi-
L •“ ••
tioning of a mechanical arm or gripper.
M ““ continuous power The maximum sine-wave power
N “• that an amplifier can deliver for 30 seconds.
O “““ continuous recorder An instrument that provides
P •““ •
an uninterrupted recording.
Q ““ •“ continuous recording A record made on a contin-
R •“ •
uous sheet or tape, instead of on separate sheets
S •••
or tapes. An example is a continuous-playing
T “ tape used for repeated public announcements.
U ••“
continuous spectrum 1. The range of all electro-
V •••“
magnetic frequencies between a specified lower
W •““


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