<<

. 7
( 42)



>>

earth group. Atomic number, 58. Atomic weight, Cord
140.13.
cerium metals A group of metals belonging to
the rare-earth group: cerium, lanthanum, chain switch
neodymium, praseodymium, promethium, and
samarium.
cermet An alloy of a ceramic, such as titanium change dump In computer operation (especially in
carbide, and nickel, a metal. A thin film of cermet debugging), the display of the names of locations
is used as a resistive element in some microcir- that have changed following a specific event.
cuits. Cermet is an acronym for ceramic metal. change file See TRANSACTION FILE.
certified tape A magnetic recording tape that has change of control In a sequence of computer
been thoroughly checked and found to have no records being processed, a logical break that ini-
flaws. tiates a predetermined action, after which pro-
cesium Symbol, Cs. A metallic element of the al- cessing continues.
kali-metal group. Atomic number, 55. Atomic changer In a high-fidelity disk player, a device that
weight, 132.91. The oscillations of this element™s allows several disks to be played, one after the
atoms have been used as atomic time standards. other, without the need for manually exchanging
The element is used in some phototubes as the the disks.
light-sensitive material, and in some arc lamps. change record A computer record that changes in-
cesium-vapor lamp A low-voltage arc lamp used formation in a related master record. Also called
as an infrared source. transaction record.
109
change tape • character density


change tape See TRANSACTION TAPE. Max Channel
channel 1. A frequency (or band of frequencies) as- separation
signed to a radio or television station. 2. See KEY-
WAY. 3. A subcircuit in a large system [e.g., the
radio-frequency (RF) channel of a receiver, the




Amplitude
vertical-amplifier channel of an oscilloscope, or the
modulator channel of a radio transmitter]. 4. The
end-to-end electrical path through the semicon-
ductor body in a field-effect transistor. 5. One of
the independent audio circuits in a stereo sound
system (e.g., the left channel or the right channel).
Min
channel analyzer A (usually multiband) continu-
ously tunable instrument, similar to a tuned ra- f1 f2 f3
dio receiver, used in troubleshooting radio
Frequency
communications circuits by substituting a per- Higher
Lower
fect channel for one that is out of order.
channel balance The state in which the apparent
channel separation, 1.
amplitude of two or more channels is identical.
channel bank In a transmission system, the termi-
nal equipment used for the purpose of multiplex- channel slot On a carrier modulated by numerous
ing the individual channels. signals, the position or frequency of a specific
channel capacity The fullest extent to which a modulating signal.
channel can accommodate the information (fre- channel shift The interchange of communications
quencies, bits, words, etc.) to be passed through it. channels (e.g., the shift from a calling frequency
channel designator A name, number, or abbrevia- to a working frequency).
tion given to a channel in a communications sys- channel strip A fixed-channel amplifier for a tele-
tem. vision receiver.
channel effect The possible current flow through a channel time slot In a frame of transmitted infor-
high impedance between the collector and emitter mation, such as a television picture, a time inter-
in a bipolar transistor. val designated to a channel for the transmission
channel frequency The CENTER FREQUENCY of of a character signal or other information.
a communications channel. channel-to-channel connection A device, such as
channeling Multiplex transmission in which sepa- a channel adapter, used to transfer data rapidly
rate carriers within a sufficiently wide frequency between any two channels of two digital comput-
band are used for simultaneous transmission. ers, at the data speed of the slower channel.
channelizing The subdivision of a relatively wide channel-utilization index An indication of the ex-
frequency band into a number of separate sub- tent to which channel capacity is used. For a
bands. given channel, the index is the ratio of informa-
channel reliability 1. The proportion of time, usu- tion rate to channel capacity, each expressed in
ally expressed as a percentage, that a communica- units per second.
tions channel is useful for its intended purpose. channel wave An acoustic wave that travels
2. The relative ease with which communications within a region or layer of a substance because of
can be carried out over a particular channel. a physical difference between that layer and the
channel reversal In stereo reproduction, inter- surrounding material. An example of a channel
changing the left and right channels. wave is the propagation of sound over a still lake.
channel-reversing switch In a stereo system, a channel width In a frequency channel, the differ-
switch that allows channel reversal without the ence f2 “ f1, where f1 is the lower-frequency limit
need for reorienting speaker cables or connectors. and f2 is the upper-frequency limit of the channel.
channel sampling rate The rate at which individ- chapter A self-contained computer program section.
ual channels are sampled. For example, in the character 1. One of the symbols in a code. 2. In
electronic switching of an oscilloscope, the num- computer operations, a digit, letter, or symbol
ber of times per second each input-signal chan- used alone or in some combination to express in-
nel is switched to the instrument. formation, data, or instructions.
channel selector A switch or relay used to put any character code In a communications or computer
of a series of channels into functional status in a system, the combination of elements (e.g., bits)
system. representing characters.
channel separation 1. The spacing between com- character crowding A reduction of the time inter-
munications channels, expressed in kilohertz. 2. val between successive characters”especially
In stereo reproduction, the degree to which the those read from tape.
information on one channel is separate from the character density The number of characters that
other; usually expressed in decibels. can be stored in a given length or surface area of
110 character density • charge carrier


a medium. On a magnetic tape, it might be spec- characteristic underflow In floating-point arith-
ified in characters per millimeter; on a magnetic metic, the condition that occurs when a charac-
disk, it might be specified in characters per teristic exceeds the lower limit specified by a
square millimeter. program or computer.
character emitter A coded-pulse generator in a character modifier In address modification, a
digital computer. constant (compare VARIABLE) that refers to a
character generator A device that converts coded specific character™s location in memory.
information into readable alphanumeric charac- character-oriented A computer in which charac-
ters. ter locations, rather than words, can be ad-
characteristic 1. A quantity that characterizes dressed.
(typifies) the operation of a device or circuit. Ex- character printer A computer output device that
amples are emitter current, output power, and prints matter in the manner of a conventional
frequency deviation. 2. In floating point notation, typewriter.
the exponent. character reader Also called an optical scanner. In
characteristic curve A curve showing the relation- a digital computer, an input device that can read
ship between an independent variable and a de- printing and script directly.
pendent variable, with respect to the parameter(s) character recognition The reading of a written or
for a device or circuit. Example: the collector volt- printed character by a computer, including its
age-collector current characteristic curve of a identification and encoding.
transistor. character sensing The detection of characters by
characteristic distortion 1. In a digital signal, a computer input device. This can be done gal-
pulse distortion caused by the effects of the pre- vanically, electrostatically, magnetically, or opti-
vious pulse or pulses. 2. Distortion in the charac- cally.
teristic curve of a component or device. character set The set of characters in a complete
characteristic frequency The frequency peculiar language, or in a communications system.
to a given channel, service, or response. character signal The set of elements or bits repre-
characteristic impedance Symbol, Z0. 1. Theo- senting a character in a digital transmission sys-
retically, the impedance that would be simulated tem. The signal can also represent the quantizing
by a given two-conductor or coaxial line of uni- value of a sample.
form construction, if that line were of infinite characters per minute An expression of the speed
length. This value is determined by the materials of transmission of a digital signal. The number of
used for the two conductors, the dielectric used characters (on average) transmitted in a period of
to insulate the two conductors, the diameters of one minute. In Morse code (CW) transmission,
the conductors, and the spacing between them. this is generally taken as the number of times the
2. In practice, for a transmission line or wave- word paris plus the subsequent space, multiplied
guide terminated with a load that produces no by six (five letters and one space following), can
standing waves on the line, the ratio of radio-fre- be sent in one minute.
quency (RF) voltage to RF current. This ratio is characters per second An expression of the speed
the same at all points along the length of a per- of transmission of a digital signal. The number of
fectly matched line, and depends on the physical characters (on average) transmitted in a period of
construction of the line. Coaxial lines typically one second.
have Z0 between 50 and 100 ohms. Twinlead is character string A one-dimensional character ar-
available with 75-ohm and 300-ohm Z0 values. ray [i.e., a list of characters that, when printed or
Open-wire line has Z0 between 300 and 600 displayed, would appear in a row or column, but
ohms, depending on the spacing between the not both (as in a matrix)].
conductors, and also on the type of dielectric (in- character subset A classification of characters
sulating material) employed to keep the spacing within a set.
constant between the conductors. 3. Experimen- Charactron A cathode-ray readout tube that dis-
tally, the value of impedance that, if it terminates plays letters, numbers, and symbols on its
a transmission line or waveguide, results in no screen. More commonly called a monitor.
reflected power from the load end of line. This is charcoal tube In a system for producing a high
always a pure resistance; that is, it contains no vacuum, a trap containing activated charcoal,
reactance. which is heated to dull red, then cooled by liquid
characteristic overflow In floating-point arith- air to absorb gases.
metic, the condition that occurs when a charac- charge 1. A quantity of electricity associated with a
teristic exceeds the upper limit specified by a space, particle, or body. 2. To electrify a space,
program or computer. particle, or body (i.e., to give an electric charge).
characteristic spread The range of values over 3. To store electricity, as in a storage battery or
which a characteristic extends. For example, if an capacitor. Compare DISCHARGE.
amplifier™s output ranges from 15 W to 25 W, its charge carrier 1. An ELECTRON whose movement
characteristic spread is 10 W. constitutes a flow of electric current. 2. An elec-
111
charge carrier • checking program


tron deficiency (HOLE) whose movement consti- in amperes or milliamperes. For most cells and
tutes a flow of electric current. 3. Any particle, batteries, the rate is greatest initially, when the
such as a charged atom (ION), PROTON, ALPHA cell or battery is depleted or nearly depleted; the
PARTICLE, or BETA PARTICLE, whose movement rate decreases as the cell or battery becomes
constitutes a flow of electric current. charged. 2. The instantaneous rate at which
charge-coupled device Abbreviation, CCD. A charging current flows into a capacitor or capaci-
form of analog-to-digital converter that generates tance-resistance circuit, expressed in amperes,
a digital signal output representing an analog milliamperes, or microamperes.
image input. The transfer of stored charges pro- charged voltage 1. The voltage across a fully
vides the method of operation. Used in machine charged capacitor. 2. The terminal voltage of a
vision systems and in numerous scientific appli- fully charged storage cell.
cations. Charlie Phonetic alphabet code word for the letter C.
charge density The degree of charge or current- chassis A (usually metal) foundation on which
carrier concentration in a region. components are mounted and wired.
charged particle 1. See CHARGE CARRIER. 2. See chassis ground A ground connection made to the
ION. metal chassis on which the components of a cir-
charged voltage 1. The voltage across a fully cuit are mounted. When several ground connec-
charged capacitor. 2. The terminal voltage of a tions are made to a single point on the chassis, a
fully charged storage cell. COMMON GROUND results.
charge holding See CHARGE RETENTION. chatter 1. A rapidly repetitive signal, caused by in-
charge of electron The negative electric charge terruption or variation of a current (usually inter-
carried by a single electron. Approximately equal ference). 2. Extraneous vibration, as of the
to 1.602 — 10“19 coulombs. armature in a relay.
charger 1. See BATTERY CHARGER. 2. Any device chatter time The interval between the instant that
or circuit that charges a capacitor. contacts close (for example, in a relay) and the in-
charge retention 1. The holding of an electric stant at which chatter ends.
charge by a cell or battery when no current is be- cheater cord An extension cord used to conduct
ing drawn from it. 2. A measure of the ability of a power to a piece of equipment (especially a televi-
cell or battery to maintain an electric charge sion receiver) by temporarily bypassing the safety
when no current is drawn from it. Often specified switch or interlock. Use of such a cord presents a
in terms of shelf life. 3. The holding of a charge by potentially fatal shock hazard to personnel using,
a capacitor. or working on, the equipment.
charge-storage tube A cathode-ray tube that holds Chebyshev filter Also spelled Tschebyscheff or
a display of information on its screen until the op- Tschebysheff. A form of inductance-capacitance
erator removes it by pressing an erase button. (LC) lowpass, highpass, bandpass, or band-
charge-to-mass The ratio of the electric charge to rejection filter, characterized by an attenuation-
the mass of a subatomic particle. versus-frequency curve with ripple in the
charge-to-mass ratio of electron The ratio of the passband.
charge (e) of the electron to the mass (me) of the check 1. A test generally made to verify condition,
electron, in coulombs per kilogram (C/kg). For an performance, state, or calculations; specifically, in
electron at rest, e/me is approximately equal to computer operations, it applies to operands or re-
1.602 — 10“19 C divided by 9.11 — 10“31 kg = 1.76 sults. 2. The usually abrupt halting of an action.
— 1011 C/kg. check bit A binary CHECK DIGIT.
charge transfer 1. The switching of an electric check character In a group of characters, one
charge from one capacitor to another. 2. The cap- whose value depends on the other characters,
ture of an electron by a positive ion from a neutral which it checks when the group is stored or
atom of the same kind, resulting in the ion be- transferred.
coming a neutral atom, and the previously neu- check digit Also called check number. In computer
tral atom becoming a positive ion. operations, a number added to a group of digits,
charge transfer device A semiconductor in which forming a code that identifies entities in the sys-
an electric charge is moved from location to loca- tem (including personnel) and can be used for
tion. Applications include delay lines, video signal verification. The check digit is the remainder
processing, and signal storage. when the number code (for example, 459) is di-
charging 1. The process of storing electrical energy vided by a fixed number (for example, 5); in this
in a capacitor. 2. The process of storing electro- case, the check digit (the remainder of 459/5) is
chemical energy in a storage cell or battery. 4, and the amended code number is 4594.
charging current 1. The current flowing into a ca- check indicator An indication, made via a video
pacitor. 2. The current flowing into a previously display, that something has been shown to be in-
discharged storage cell. valid according to a check.
charging rate 1. The rate at which charging cur- checking program Also called checking routine.
rent flows into a storage cell or battery, expressed For debugging purposes, a diagnostic computer
112 checking program • chirp


program capable of detecting errors in another ample is the stored energy in terms of watt hours
program. in an electrolytic cell.
checkout A test routine that ascertains whether or chemical load An arrangement of a chemical ma-
not a circuit or system is functioning according to terial or device for the passage of electricity
specifications. through it. Examples: electroplater, electrolytic
checkout routine A routine used by programmers cell for the production of hydrogen gas, and stor-
to debug programs. age battery.
checkpoint A point in a digital-computer program chemically deposited printed circuit A printed
at which sufficient information has been stored to circuit in which the pattern of metal lines and ar-
allow restarting the computation from that point. eas are chemically deposited on a substrate.
checkpoint dump The process of recording details chemically pure Abbreviation, CP. Free from im-
of a computer program run. This process might purities.
be necessary in the event of a system failure that chemical rectifier See ELECTROLYTIC CELL.
requires reconstruction of a program or pro- chemical reduction The process of making a
grams. chemical compound (usually in solution) into a
checkpointing The writing of a computer program metal, by removing the nonmetallic component
in such a manner that, during a program run, in- from the compound. For example, when copper
formation is frequently dumped as insurance oxide is heated in the presence of hydrogen (a re-
against possible loss in the event of a system fail- ducting agent), the oxygen (the nonmetallic com-
ure. ponent) is driven out, and copper (along with
check problem A presolved problem used to check some water) remains.
the operation of a digital computer or program. chemical resistor See ELECTROLYTIC RESIS-
check register In some digital computers, a regis- TOR.
ter in which transferred information is stored so chemical switch See ELECTROCHEMICAL
that it can be checked against the same informa- SWITCH.
tion as it is received a second time. CHIL Abbreviation for current-hogging injection
check routine A special program designed to as- logic. A form of bipolar digital logic technology.
certain if a program or computer is operating cor- chip 1. An INTEGRATED CIRCUIT. 2. A small slab,
rectly. Also see CHECK PROBLEM. wafer, or die of dielectric or semiconductor mate-
checksum Used as part of a summation check, a rial, on which a subminiature component or cir-
sum derived from the digits of a number. For ex- cuit is formed or deposited.
ample, the checksum of 23,335 is 16. Also called chip capacitor A subminiature capacitor formed
HASH TOTAL. on a chip.
check symbol For a specific data item, a digit or chip resistor A subminiature resistor formed on a
digits obtained by performing an arithmetic chip.
check on the item, which it then accompanies chip tray A chad receptacle located at a card or pa-
through processing stages for the purpose of per tape punching site.
checking it. Chireix-Mesny antenna A high-frequency (HF)
check total See CONTROL TOTAL. beam antenna, in which each dipole section con-
check word A check symbol in the form of a word stitutes one side of a diamond. Cophased hori-
added to, and containing data from, a block of zontal and vertical components of current flow in
records. each of the diagonals, and radiation is broadside
chelate Pertaining to cyclic molecular structure in to the plane of the driven element.
which several atoms in a ring hold a central
metallic ion in a COORDINATION COMPLEX.
chemical deposition The coating of a surface with
a substance resulting from chemical reduction of
a solution. In mirror making, for example,
formaldehyde reduces a solution of silver nitrate, Maximum
and deposits metallic silver on the surface of pol- radiation
ished glass. Also see CHEMICALLY DEPOSITED
PRINTED CIRCUIT and CHEMICAL REDUCTION.
chemical detector See ELECTROLYTIC DETEC- Feed
TOR. line
chemical effect An alteration in the chemical
makeup of a substance or solution, resulting Chireix-Mesny antenna
from the passage of an electric current through it.
Examples include electrolysis, electroplating, and
the reduction of ores. chirp A rapid change in the frequency of a contin-
chemical energy Energy that is stored in the uous-wave Morse-code signal. The chirp usually
chemical bonds of a material or solution. An ex- occurs at the beginning of each dot or dash, and
113
chirp • chopper power supply


can go up or down in frequency. Chirp occurs be- Filter
choke
cause of a change in the output impedance of an
oscillator as it is keyed. Modern code transmitters
do not exhibit significant chirp.
+ +
chirp modulation A form of modulation in which
the frequency of a signal is deliberately changed
in a systematic way. Used in some radar systems.
+
chirp radar A radar system that uses CHIRP MOD- Filter
Pulsating Smoothed
ULATION. capacitor
dc input dc output
Chladni™s plates Conducting plates that are used
to evaluate the nature of a vibration in a solid ma-
terial. The plates are clamped to the material, and
’ ’
sand is sprinkled on the surface. This produces
patterns that indicate the nature of the vibra-
tions.
chlorinated diphenyl A synthetic organic sub-
stance used as an impregnant in some oil-filled choke-input filter
capacitors.
chlorinated naphthalene See HALOWAX.
chopper A device or circuit that interrupts a direct
chlorine Symbol, Cl. A gaseous element of the
current (dc) at some predetermined rate. Ideally,
halogen family. Atomic number, 17. Atomic
such a device is characterized by distinct on and
weight, 35.453.
off operation.
choke 1. To restrict or curtail passage of a particu-
chopper amplifier A circuit that amplifies the out-
lar current or frequency by means of a discrete
put of a CHOPPER. Used in conjunction with a
component, such as a choke coil. 2. See CHOKE
CHOPPER CONVERTER in dc amplification.
COIL.
chopper converter A device that interrupts a di-
choke air gap A fractional-inch opening in the iron
rect current (dc), and changes it to a pulsating,
core of a filter choke, usually filled with wood or
rectangular-wave current or voltage that can be
plastic. The gap prevents saturation of the core
handled by a stable ac amplifier and rectified to
when the choke coil carries maximum rated di-
supply amplified dc.
rect current.
chopper power supply Also called power inverter.
choke coil 1. A large-value inductor that provides
A circuit that delivers high-voltage ac from a dc
a high impedance to alternating current (ac),
source. The input is typically 12 volts dc, and the
while offering virtually no opposition to direct
output is usually 117 volts rms ac. These devices
current (dc). 2. In radio-frequency (RF) applica-
facilitate the use of small appliances such as
tions, an inductor that provides a high
computers, television sets, and communications
impedance to RF signals while showing low
radios in portable and mobile environments. The
impedance for audio-frequency (AF) signals and
output of a low-cost power inverter is generally
direct currents (dc).
not a good sine wave. More sophisticated invert-
choke-coupled modulation An amplitude-
ers produce good sine waves and have a fre-
modulation (AM) scheme, in which the modulator
quency close to 60 Hz.
is coupled to the radio-frequency (RF) amplifier
through a shared iron-core choke coil.
choke flange At the end of a waveguide, a flange in
which a groove forms a CHOKE JOINT.
choke-input filter A filter whose input component
is an inductor (choke). The choke-input power-
supply filter is distinguished by its superior
voltage regulation, compared with the
CAPACITOR-INPUT FILTER.
choke joint A joint connecting two waveguide sec-
tions and permitting efficient energy transfer
without requiring electrical contact with the in-
side wall of the waveguide.
chopped dc See INTERRUPTED DC.
chopped mode In a single-gun cathode-ray-tube
(CRT) oscilloscope, a technique for sequentially
displaying several signals that are not referenced
to the oscilloscope sweep.
chopped signal An ac or dc signal that is periodi-
cally interrupted, as by means of a CHOPPER.
114 chopper stabilization • chrominance modulator


chopper stabilization 1. Stabilization of direct- color in terms of dominant or complementary
current (dc) amplification by using a CHOPPER wavelength and purity.
CONVERTER ahead of a stable ac amplifier, and chromaticity coordinate For a color sample, the
rectifying the amplifier output. 2. In a regulated ratio of any one of the three tristimulus values
power supply, use of a CHOPPER AMPLIFIER at (primary colors) to the sum of the three.
the control-circuit input to improve regulation. chromaticity diagram A rectangular-coordinate
chopper-stabilized amplifier See CHOPPER AMP- graph in which one of the three CHROMATICITY
LIFIER and CHOPPER STABILIZATION, 1. COORDINATES of a three-color system is plotted
chopper transistor A transistor that provides against another coordinate.
rapid and repeated on/off switching of direct cur- chromaticity flicker Flicker caused entirely by
rent (dc), in the manner of an electromechanical chromaticity fluctuation (see CHROMATICITY, 2).
interrupter. See CHOPPER. chromel A nickel-chromium alloy with some iron
chopping frequency The frequency at which a content, used in thermocouples.
chopper interrupts a signal. chromel-alumel junction A thermocouple that
chord 1. A harmonious mixture of musical tones of uses wires of the alloys chromel and alumel.
various frequencies. 2. A straight line that joins chromel-constantan thermocouple A thermo-
two points on a curve (such as an arc of a circle). couple consisting of a junction between wires or
3. The width of an airfoil. strips of chromel and constantan. Typical output
chord organ An electronic organ that will sound a is 6.3 mV at 100°C.
musical chord when a key is pressed (see chrome plating The process of coating a metal
CHORD, 1). with chromium. Generally protects against corro-
choreographer program A computer program sion.
similar to one originally written by Charles Lecht chrome recording tape Also called chrome tape or
of Lecht Sciences, Inc. The computer operator chromium tape. Tape that is manufactured from
gives commands that cause a human form, por- the compound chromium dioxide. Noted for its
trayed on the display screen, to make various ability to faithfully record and reproduce music.
movements. Used in animated computer graph- chrominance In color television, the difference be-
ics. tween a reproduced color and a standard refer-
chorus Signals at very low radio frequencies ence color of the same luminous intensity.
(VLF), natural in origin, that sweep upward in chrominance amplifier In a color television cir-
frequency. Believed to result from lightning- cuit, the amplifier separating the chrominance
generated electromagnetic fields that circulate in signal from the total video signal.
the magnetosphere (earth™s magnetic field). The chrominance cancellation On a black-and-white
term is derived from the sound the signals make picture tube screen, cancellation of the fluctua-
in high-gain audio-frequency (AF) amplifiers con- tions in brightness caused by a chrominance sig-
nected directly to VLF receiving antennas. nal.
Christiansen antenna A radio-telescope antenna chrominance-carrier reference In color televi-
for obtaining high resolution. Two straight arrays sion, a continuous signal at the frequency of the
are placed at an angle, intersecting approxi- chrominance subcarrier; it is in fixed phase
mately at their centers. The resulting interference with the color burst and provides modulation
pattern has extremely narrow lobes. or demodulation phase reference for carrier-
Christmas tree A tree-like pattern on the screen of chrominance signals.
a television receiver, caused by loss of horizontal chrominance channel In color television, a circuit
synchronization. devoted exclusively to the color function, as op-
chroma The quality of a color: hue and saturation. posed to audio and general control channels.
chroma circuit In color television, one of several chrominance component In the NTSC color tele-
circuits whose ultimate purpose is to produce a vision systems, either of the components (I-signal
color component on the screen. or Q-signal) of the complete chrominance signal.
chroma-clear raster In color television reception, chrominance demodulator In a color television
the clear raster resulting from a white video sig- receiver, a demodulator that extracts video-
nal, or from operation of the chroma circuits of frequency chrominance components from the
the receiver (as if they were receiving a white chrominance signal, and a sine wave from the
transmission). Also called white raster. chrominance subcarrier oscillator.
chroma control In a color television receiver, a chrominance gain control A rheostat or poten-
rheostat or potentiometer that permits adjust- tiometer in the red, green, and blue matrix chan-
ment of color saturation through variation of the nels of a color television receiver, used to adjust
chrominance-signal amplitude before demodula- the primary-signal amplitudes.
tion. chrominance modulator In a color television
chromatic fidelity See COLOR FIDELITY. transmitter, a device that generates the chromi-
chromaticity 1. The state of being chromatic (see nance signal from the I and Q components and
CHROMA). 2. A quantitative assessment of a the chrominance subcarrier.
115
chrominance primary • circuit diagram


chrominance primary One of the transmission circuit 1. A closed path through which current
primaries (red, green, and blue) upon which the flows from a generator, through various compo-
chrominance of a color depends. nents, and back to the generator. (An electronic
chrominance signal The signal component in circuit is often a combination of interconnected
color television that represents the hues and sat- subcircuits.) 2. The wiring diagram of an elec-
uration levels of the colors in the picture. tronic device or system.
chrominance subcarrier In color television, the circuit analysis The careful determination of the
3579.545-kHz signal that serves as a carrier for nature and behavior of a circuit and its various
the I- and Q-signals. parts. It can be theoretical, practical, or both.
chrominance-subcarrier oscillator In a color tele- Compare CIRCUIT SYNTHESIS.
vision receiver, a crystal-controlled oscillator that circuit analyzer See CIRCUIT TESTER.
generates the subcarrier signal (see CHROMI- circuit board A panel, plate, or card on which elec-
NANCE SUBCARRIER). tronic components are mounted and intercon-
chrominance video signals Output signals from nected to provide a functional unit.
the red, green, and blue channels of a color tele- circuit breaker A resettable fuse-like device that is
vision camera or receiver matrix. designed to protect a circuit against overloading.
chromium Symbol, Cr. A metallic element. Atomic In a typical circuit breaker, the winding of an
number, 24. Atomic weight, 51.996. Commonly electromagnet is connected in series with the load
used as a plating for metals to improve resistance circuit and with the switch contact points. Exces-
to corrosion. sive current through the magnet winding causes
chronistor An elapsed-time indicator in which the switch to be opened.
current, flowing during a given time interval,
electroplates an electrode. The duration of the
interval is determined from the amount of de-
posit.
chronograph 1. An instrument that provides an
accurate time base along the horizontal axis of its
permanent record. 2. Stopwatch.
chronometer A precision clock. Electronic chron-
Armature
ometers often use a highly accurate and stable
crystal oscillator, followed by a string of multivi-
brators to reduce the crystal frequency to an au-
dio frequency (such as 1 kHz) that drives the Load circuit
clock motor. in series with coil
Springs
chronoscope An instrument for precisely measur-
ing small time intervals. Power supply
CHU Call letters of the Canadian time-signal sta-
tion whose primary frequency is 7.335 MHz.
circuit breaker
Ci Symbol for INPUT CAPACITANCE.
CIE Abbreviation for International Commission on
Illumination. circuit capacitance The total capacitance
cinching In a reel of magnetic tape, the slipping of (lumped, distributed, and stray) present in a cir-
tape as force is applied. cuit.
cinematograph See KINEMATOGRAPH. circuit capacity 1. The ability of a circuit to han-
cipher A code used for the purpose of preventing dle a quantity (such as current, voltage, fre-
interception of a message by third parties. quency, power, etc.) safely and efficiently. 2. The
circ 1. Abbreviation of circuit. 2. Abbreviation of maximum value of some parameter at which a
circular. circuit can function safely and efficiently (e.g., a
circle graph Also called a pie graph. A represen- circuit capacity of 50 A). 3. The number of chan-
tational device consisting of a disk subdivided nels that can be accommodated simultaneously
into various triangular areas (radiating from the by a circuit.
center of the circle), which are proportional to circuit component 1. Any of the electronic devices
represented quantities. or parts (capacitors, resistors, transistors, etc.)
circle of confusion A circular image of a point that are connected through wiring to form a cir-
source of light, resulting from an aberration in an cuit. 2. An electrical quantity required for, or
optical system. arising from, circuit operation. Examples: input
circle of declination The graduated circular scale voltage, feedback current, stray capacitance, and
of a declinometer. circuit noise.
circlotron amplifier A high-powered microwave circuit diagram A drawing in which symbols and
amplifier of the one-port, cross-field, nonlinear lines represent the components and wiring of
type using a magnetron. an electronic circuit. Also called CIRCUIT
116 circuit diagram • circular magnetic wave


SCHEMATIC, SCHEMATIC DIAGRAM, and connection is maintained even during periods of
WIRING DIAGRAM. silence (no data transmitted by either sub-
circuit dropout A momentary interruption of cir- scriber). Compare PACKET SWITCHING.
cuit operation, often caused by a break in the cir- circuit synthesis The development of a circuit un-
cuit. der the guidance of theoretical or practical knowl-
circuit efficiency A quantitative measure of the edge of basic electronics principles and
effectiveness of circuit operation, customarily ex- component parameters. Compare CIRCUIT
pressed as the ratio of the useful output power to ANALYSIS.
the total input power. circuit tester An instrument for checking the per-
circuit element See CIRCUIT COMPONENT, 1. formance of electronic circuits. Often consists of
circuit engineer An electronics engineer who spe- a specialized continuity tester, but occasionally it
cializes in circuit analysis, circuit synthesis, or includes a dynamic performance tester.
both. circuit tracking The alignment and/or pretuning
circuit fault 1. Malfunction of a circuit. 2. An error of circuits for identical or optimum response. It
in circuit wiring. applies especially to cascaded circuits, whose
circuit hole A perforation within the conductive variable elements, such as tuned inductance-
area of a printed-circuit board, for the insertion capacitance (LC) networks, must follow each
and connection of a pigtail, terminal, etc., or for other in step when ganged together.




Y
connecting the conductors on one side of the circular angle The angle described by a radius vec-
board with those on the other. tor as it rotates counterclockwise around a circle.




FL
circuit loading Intentionally or unintentionally circular antenna A half-wave horizontally polar-
drawing power from a circuit. ized antenna, whose driven element is a rigid
circuit noise 1. Electrical noise generated by a cir- conductor bent into a circle with a break opposite
cuit in the absence of an applied signal. 2. In wire the feed point. Also called halo antenna. Used pri-
AM
telephony, electrical noise as opposed to acoustic marily at very-high frequencies (VHF).
noise. circular electric wave An electromagnetic wave
circuit noise level The ratio of circuit-noise ampli- with circular electric lines of flux. An example is
tude to reference-noise amplitude, expressed in the field in the immediate vicinity of a CIRCULAR
decibels above the reference amplitude. ANTENNA.
TE

circuit-noise meter A meter that measures the in-
tensity of the noise generated within a circuit.
circuit parameter See CIRCUIT COMPONENT, 2.
Electric lines
Loop
circuit protection Automatic safeguarding of a
of flux
carrying ac
circuit from damage from overload, excessive
drive, heat, vibration, etc. Protection is afforded
by various devices and subcircuits, ranging from
the common fuse to sophisticated limiters and
breakers.
circuit reliability A quantitative indication of the
ability of a circuit to provide dependable opera-
tion as specified. See MEAN TIME BEFORE FAIL-
URE and MEAN TIME BETWEEN FAILURES.
circuitry 1. Collectively, electronic and electrical
circuits. 2. A detailed plan of a circuit and its
subcircuits. 3. Collectively, the components of a
circuit.
circuit schematic See CIRCUIT DIAGRAM.
circuit simplification 1. In circuit analysis, the
reduction of a complex circuit to its simplest rep-
circular electric wave
resentation to minimize labor and to promote
clarity. Thus, through application of Kirchhoff™s
laws, a complicated circuit could theoretically be circular functions Trigonometric functions of the
reduced to a single generator in series with a sin- angle described by a vector rotating counter-
gle impedance. 2. In circuit synthesis, the ar- clockwise around a circle. Also see COSINE,
rangement of a circuit so as to provide desired COSECANT, COTANGENT, SECANT, SINE, and
performance with the fewest components and TANGENT.
least-complex wiring. circular magnet See RING MAGNET.
circuit switching In telephony, a method of con- circular magnetic wave An electromagnetic wave
nection in which a single circuit is maintained be- in which the magnetic lines of flux are circular.
tween two subscribers for the entire duration of An example is the field in the immediate vicinity
the call. The signal path does not change. The of a straight-conductor antenna.




Team-Fly®
117
circular mil • class-A amplifier


circulating tank current The alternating current
that oscillates between the capacitor and induc-
tor within a tank circuit.
circulator A multi-terminal coupler in which mi-
crowave energy is transmitted in a particular di-
Magnetic lines
rection from one terminal to the next.
of flux
circumvention In a security or alarm system, the
evasion of detection. Can be done by physically
avoiding regions of coverage, or by defeating the
system electronically.
cis A prefix meaning “on this side of.” For example,
the cislunar field is the field on this side of the
moon.
Citizen Band Abbreviation, CB. A band of radio
frequencies allocated for two-way communication
Conductor
between private citizens (apart from amateur and
carrying ac
commercial services).
Citizens Radio Service Two-way radio communi-
cation in a CITIZEN BAND. In the United States,
the FCC licenses users of this service without re-
quiring them to take an examination.
C/kg Abbreviation of coulombs per kilogram, the
unit for electron charge-to-mass ratio.
C/kmol Abbreviation of coulombs per kilomole, the
unit for the Faraday constant.
ckt Abbreviation of CIRCUIT.
circular magnetic wave
Cl Symbol for CHLORINE.
cl Abbreviation of CENTILITER.
cladding The bonding of one metal to another to
circular mil A unit of cross-sectional area equiva-
minimize or prevent corrosion. A common exam-
lent to 0.785 millionths of a square inch, or the
ple is copper-clad steel wire, ideal for use in
area of a circle having a diameter of 0.001 inch.
radio-frequency antenna systems. The copper
Generally, the circular mil is used to specify the
provides excellent conduction, and the steel pro-
cross-sectional area of a conductor, such as wire.
vides high tensile strength with a minimum of
circular mil foot A unit of volume in which the
wire stretching.
length is 1 foot and the cross-sectional area is 1
clamper A device that restricts a wave to a prede-
circular mil.
termined dc level. Also called DC RESTORER.
circular polarization A form of electromagnetic-
clamping 1. Fixing the operation of a device at a
wave polarization in which the orientation of the
definite dc level. Also see CLAMPER. 2. In televi-
electric flux rotates continuously and uniformly
sion, establishing a fixed level for the picture sig-
as the wave propagates through space. Circular
nal at the start of each scanning line.
polarization can occur in either a clockwise or
clamping circuit See CLAMPER.
counterclockwise sense.
clamping diode A diode used to fix the voltage
circular radian The angle enclosed by two radii of
level of a signal at a particular reference point.
a unit circle and subtended by a unit arc. Equal
clapper In a bell, the ball or hammer that strikes
to about 57.296 angular degrees.
the bell; in an electric bell, it is affixed to the vi-
circular scan A radar scan in which the electron-
brating armature.
beam spot describes a circle centered around the
Clapp-Gouriet oscillator A Colpitts oscillator in
transmitting antenna.
which a capacitor is connected in series with the
circular sweep In an oscilloscope, a sweep ob-
inductor. The circuit offers high frequency stabil-
tained when the horizontal and vertical sinu-
ity in the presence of input and output capaci-
soidal deflecting voltages have the same
tance variations.
amplitude and frequency, but are out of phase by
Clapp oscillator A series-tuned hybrid Colpitts os-
90 degrees (1 „4 cycle).
cillator, having a tuning capacitor in series with
circular trace An oscilloscope pattern consisting
the inductor, rather than in parallel with the in-
of a circle obtained with a circular sweep of the
ductor. The circuit allows the use of a smaller
electron beam.
tuning capacitor, resulting in improved stability.
circular waveguide A waveguide with a circular
Clark cell See ZINC STANDARD CELL.
cross section.
class-A amplifier An amplifier whose bias is set at
circulating register In a digital computer, a regis-
approximately the midpoint of the characteristic
ter in which digits are taken from locations at one
curve. Output electrode current flows during the
end and returned to those at the other end.
118 class-A amplifier • click method


+ class-C amplifier An amplifier whose input-elec-
trode bias is adjusted for operation at a point
considerably beyond cutoff. Output current flows
during less than half of the input signal cycle.
Such an amplifier requires comparatively high
driving power, but is capable of excellent effi-
Out ciency. Commonly used in continuous-wave
(CW), amplitude-modulated (AM), and frequency-
modulated (FM) radio transmitters.
{
Freq.
class-C operation The operation of a transistor,
adj.
field-effect transistor, or vacuum tube, in which
the collector, drain, or plate current flows for sig-
nificantly less than half the signal cycle.
class-D telephone A telephone restricted to use by
emergency services, such as fire departments
and guard alarm installations.
classical electron radius Abbreviated re. The
quantity expressed as e 2/(mec 2), where e is the
electron™s charge in electrostatic units, me is its
rest mass, and c is the speed of light. The value
re is equal to approximately 2.82 — 10“13 cm or
Clapp oscillator
2.82 — 10“15 m.
clean room A room for the assembly or testing of
complete ac driving-voltage cycle. The input sig-
critical electronic equipment. The term is derived
nal never drives the device into the nonlinear por-
from the extraordinary steps taken to remove
tion of the characteristic curve.
dust and other contaminating agents. The per-
class-AB amplifier Either a CLASS-AB1 AMPLI-
sonnel wear carefully cleaned garments (or dis-
FIER or a CLASS-AB2 AMPLIFIER.
posable clothing), gloves, caps, and masks; in
class-AB1 amplifier An amplifier whose bias is ad-
some situations, they are required to walk be-
justed to a level between that of a class-A ampli-
tween ceiling and floor ducts of a vacuum system
fier and that of a class-AB2 amplifier. Output
upon entering the room.
electrode current flows during the entire ac driv-
cleanup process In the process of electron tube
ing-voltage cycle. The input signal drives the
evacuation, a technique used to remove residual
device into the nonlinear portion of the
and occluded gases from the vacuum apparatus
characteristic curve during part of the cycle.
and from the device being evacuated.
class-AB2 amplifier An amplifier whose bias is ad-
clear 1. In computer operations, to restore a
justed to a level between that of a class-AB1 am-
switching element (e.g., a flip-flop) or a memory
plifier and that of a class-B amplifier. Output
element to its standard (e.g., zero) state. 2. In
electrode current flows during more than 50 per-
computer practice, an asynchronous input.
cent, but less than 100 percent, of the input sig-
clearance The distance between two live terminals,
nal cycle.
or between one live terminal and ground.
class-AB modulator A modulator whose output
clear band In optical character recognition, the
stage is a class-AB1 or class-AB2 amplifier.
part of a document that must remain unprinted.
class-A modulator A circuit for obtaining ampli-
clear channel 1. A channel in the standard ampli-
tude-modulated signals; essentially a class-A am-
tude-modulation (AM) broadcast band that is des-
plifier with two inputs, one for the carrier and the
ignated to only one station within the area covered
other for the modulating signal.
by the signal from that station. 2. In television
class-A operation The operation of a transistor,
broadcasting, a channel for which there are no re-
field-effect transistor, or vacuum tube, in which
strictions on the nature of the programming.
the collector, drain, or plate current flows during
clear memory A function in a calculator or small
the entire signal cycle.
computer that erases the contents of the mem-
class-B amplifier An amplifier whose bias is ad-
ory.
justed to operate at the cutoff point in the charac-
clear raster The raster on the screen of a television
teristic curve. Output current flows during
picture tube in the absence of a signal, noise, or
approximately 50 percent of the input signal cycle.
faulty beam deflection.
Efficiency is higher than that of a class-A amplifier.
cleavage In a crystalline substance, the quality of
class-B modulator A push-pull modulator whose
splitting along definite planes. Also, a fragment
output stage is a class-B amplifier.
resulting from such a cleft.
class-B operation The operation of a transistor,
click filter See KEY-CLICK FILTER.
field-effect transistor, or vacuum tube, in which
click method An emergency technique for render-
the collector, drain, or plate current flows for ap-
ing an electric current audibly detectable, by
proximately half the signal cycle.
119
click method • closed-circuit security system


making and breaking the circuit carrying the cur- clocked flip-flops A master-slave arrangement of
rent to a headset or earphone. A single click re- direct-coupled flip-flops. Information entered into
sults from each make and each break. Also see the master unit when the input-trigger pulse am-
TIKKER. plitude is high is transferred to the slave unit
click suppressor See KEY-CLICK FILTER. when the amplitude is low.
climate chamber A test chamber that provides ac- clock frequency In a digital computer or control,
curately controlled temperature, humidity, and/or the reciprocal of the period of a single cycle, ex-
barometric pressure, for evaluating the perfor- pressed in terms of the number of cycles occur-
mance of electronic components and circuits. Also ring in one second of time (hertz, kilohertz, or
called ENVIRONMENTAL TEST CHAMBER. megahertz).
climatometer An instrument incorporating a hy- clock generator A test-signal generator that sup-
grometer and bimetallic thermometer, whose dial plies a chain of pulses identical to those supplied
pointers intersect to indicate comfort zones (best by the clock of a digital computer.
temperature-to-humidity ratio). clock module A complete plug-in or wire-in digital
clinometer An electromechanical device that mea- unit whose readout indicates time of day or
sures the steepness of a slope. When the device is elapsed time. Connected to a suitable power sup-
level (horizontal), the output voltage is zero. If the ply, it serves as either a clock or timer.
device is tipped in one direction, a negative volt- clock pulse A time-base pulse supplied by the
age is produced; if it is tipped in the other direc- clock of a digital computer, expressed as a period
tion, a positive voltage is produced. The output whose reciprocal is frequency.
voltage is proportional to the angle at which the clock rate See CLOCK FREQUENCY.
device is tipped. Used in mobile robots. clock track On a magnetic tape or disk for data
clip A pinch-type connector whose jaws are nor- storage, a track containing read or write control
mally held closed by a spring. (clock) pulses.
clockwise Abbreviation, cw. Rotation in a right-
hand direction around a circle, starting at the
top. Compare COUNTERCLOCKWISE.
clockwise-polarized wave An elliptically polarized
electromagnetic wave whose electric-intensity
clip vector rotates clockwise, as observed from the
point of propagation. Compare COUNTER-
CLOCKWISE-POLARIZED WAVE.
clipped-noise modulation Modulation of a jam-
clone A machine manufactured by a relatively un-
ming signal through clipping action to increase
known company that performs all the same func-
the sideband energy and resulting interference.
tions, in basically the same way, as another
clipper A circuit whose output voltage is fixed at a
machine manufactured by a well-known, major
value for all input voltages higher than a prede-
corporation. The term is used especially in refer-
termined value. Clippers can flat-top the positive,
ence to computers and computer peripherals. If a
negative, or both positive and negative peaks of
device is compatible with a certain computer,
an input voltage.
then clones of that device are generally compati-
clipper amplifier An amplifier operated so that the
ble with that computer. Also, the device is likely
positive, negative, or both positive and negative
to be compatible with all clones of the computer.
peaks are clipped in the output signal. The clip-
close coupling Also called tight coupling. In a
ping action results from feeding a regular sym-
transformer, the placement of the primary and
metric waveform into an amplifier so that on
secondary coils as close together as possible for
negative excursion extremes, the stage is cut off;
maximum energy transfer. Compare LOOSE
on positive excursion extremes, the amplifier is
COUPLING.
driven into saturation.
closed capacitance The value of a variable capaci-
clipper limiter A device that delivers an output sig-
tor whose rotor plates are completely meshed with
nal whose amplitude range corresponds to input-
the stator plates. Compare OPEN CAPACITANCE.
signal voltages between two predetermined limits.
closed circuit A continuous unbroken circuit (i.e.,
It can be used as a noise limiter with an element or
one in which current can flow without interrup-
elements that clip all pulses whose amplitudes are
tion). Compare OPEN CIRCUIT.
greater than the signal being processed.
closed-circuit cell A primary cell, such as the
clipping 1. Leveling off (flat-topping) a signal peak
early gravity cell, designed for heavy and polar-
at a predetermined level. Also see CLIPPER. 2. In
ization-free service.
audio practice, the loss of syllables or words be-
closed-circuit communication Communication
cause of cutoff periods in the operation of the cir-
between units only within a defined, hard-wired
cuit (usually caused by overdriving a stage).
system, not extending to other units or systems.
clock In a digital computer or controller, the device
closed-circuit security system An electronic se-
or circuit that supplies timing pulses to pace the
curity or alarm system, consisting of subsystems
operation of the system.
120 closed-circuit security system • CMR


interconnected so that a disturbance anywhere in is a voltage regulator, in which a rise in output
the circuit will result in an alarm signal pinpoint- voltage is fed back to the input. This changes the
ing the location of the disturbance. input voltage and reduces the output voltage to
closed-circuit signaling Signaling accomplished its correct value. Compare OPEN-LOOP CON-
by raising or lowering the level of a signaling cur- TROL SYSTEM.
rent flowing continuously in a circuit. closed-loop input impedance The input imped-
closed-circuit television Abbreviation, CCTV. A ance of an amplifier that has feedback.
usually in-plant television system, in which a closed-loop output impedance The output im-
transmitter feeds one or more receivers through a pedance of an amplifier that has feedback.
cable. closed-loop voltage gain The voltage gain of an
closed core A magnetic core generally constructed amplifier that has feedback.
in an “O” or “D” configuration to confine the mag- closed magnetic circuit A magnetic circuit in
netic path to the core material. Compare OPEN which the flux is uninterrupted, as in a ferromag-
CORE. netic core, which has no air gap. Also see
closed-core choke A choke coil wound on a CLOSED CORE.
CLOSED CORE. Also called CLOSED-CORE IN- closed subroutine In a digital computer program,
DUCTOR. a subroutine that can be accessed and left by
branch instructions, such as GOSUB and RE-
TURN in the high-level language BASIC.
close-spaced array A beam antenna in which the
elements (radiator, director, and reflector) are
spaced less than a quarter-wavelength apart.
close-talk microphone A microphone that must
be placed close to the mouth. Such a microphone
is less susceptible to background noises than an
ordinary microphone, and is useful in environ-
ments where the ambient noise level is high.
closing rating A specification for closure condi-
tions in a relay, including duty cycle and contact
life (total guaranteed closures before contact
failure).
closure 1. The act of closing or being closed (e.g.,
closed-core choke
switch closure or relay closure). 2. Circuit com-
pletion (i.e., the elimination of all discontinuities).
cloud The mass of electrons constituting the space
closed-core transformer A transformer wound on
charge in a vacuum tube.
a CLOSED CORE.
cloverleaf antenna An omnidirectional transmit-
ting antenna in which numerous horizontal,
four-element radiators (stacked vertically, a quar-
Laminated core
ter-wavelength apart) are arranged in the shape
of a four-leaf clover.
C/L ratio See LC RATIO.
Primary Secondary clutter Extraneous echoes that interfere with the
image on a radar display.
clutter gating In radar operations, a switching
process that causes the normal video to be dis-
played in regions free of clutter, and the video in-
closed-core transformer
dicating target movement to be displayed only in
cluttered areas.
Cm Symbol for CURIUM.
closed loop 1. The feedback path in a self-regulat-
cm Abbreviation of CENTIMETER.
ing control system. An oscillator, for example, is a
c.m. Abbreviation of CIRCULAR MIL.
closed-loop amplifier. 2. A loop within a program
cm2 Abbreviation of square centimeter.
that would continue indefinitely, except for an ex-
cm3 Abbreviation of cubic centimeter.
ternal exit command.
Cmax Abbreviation of maximum capacitance.
closed-loop bandwidth The frequency at which
C meter See CAPACITANCE METER.
the gain of a closed-loop circuit (see CLOSED
Cmin Abbreviation of minimum capacitance.
LOOP, 1) drops 3 decibels from the direct-current
CML Abbreviation of CURRENT-MODE LOGIC.
or midband value.
CMOS Abbreviation of COMPLEMENTARY METAL-
closed-loop control system A control system in
OXIDE SEMICONDUCTOR.
which self regulation is obtained by means of a
CMR See COMMON-MODE REJECTION.
feedback path (see CLOSED LOOP). An example
121
CMRR • coaxial capacitor


CMRR See COMMON-MODE REJECTION RATIO. wave vertical radiator that is insulated from, and
CMV See COMMON-MODE VOLTAGE. that extends upward from the top of, the lower
C network A circuit with three impedances con- section.
nected in series, the free leads being connected to coaxial cable An unbalanced cable consisting of
a pair of terminals and the two internal junctions, two concentric conductors: an inner wire and an
to another pair of terminals. outer, braided sleeve. The inner and outer con-
Co Symbol for COBALT. ductors are separated by a dielectric, usually
Co Symbol for OUTPUT CAPACITANCE. solid or foamed polyethylene. The outer conduc-
coalesce In computer operations, to create one file tor is generally grounded while the inner conduc-
from several. tor carries the signals. This cable is used in
coarse adjustment Adjustment of a quantity in community-antenna television (CATV) networks,
large increments. Compare FINE ADJUSTMENT. and as a transmission line connecting antennas
coarse-chrominance primary See Q SIGNAL. to radio transmitters, receivers, and transceivers
coastal bending A change in the horizontal direc- at low, medium, high, and very-high frequencies.
tion of a line-of-sight radio wave when it crosses a It is also used in some high-fidelity sound sys-
coastline. tems”especially to connect microphones, com-
coast station In the Maritime Mobile Radio Ser- pact-disc players, tape players, tuners, and
vice, a land station that communicates with ship- speakers to audio amplifiers.
board stations.
coating 1. The application of a substance to an-
other substance by means of electroplating, elec-
trophoresis, or similar process, for the purpose of
protecting the material, isolating it from the envi-
coaxial cable
ronment, or improving the conductivity of an
(From left to right: insulating jacket,
electrical connection to some other object. 2. The
woven outer conductor, low-loss insulating
magnetic material on a recording tape. 3. In a
sleeve, inner conductor.)
computer system, the magnetic material on a
magnetic diskette or hard disk.
coating thickness On magnetic tape or magnetic
Characteristics of
disks, the depth of the magnetic coating applied
prefabricated coaxial transmission lines.
to the base.
coax Abbreviation of COAXIAL CABLE or COAXIAL
Characteristic
LINE.
impedance, Velocity Outside Picofarads
coaxial antenna A half-wave vertical antenna that
Type (ohms) factor dia. (in.) per foot
is center-fed by coaxial cable. The cable runs up-
ward through a 1„4-wave section of tubing that
RG-8/U 52 0.66 0.41 29.5
composes the lower half of the antenna. The
RG-9/U 51 0.66 0.42 30.0
outer conductor of the cable is connected to this
RG-11/U 75 0.66 0.41 20.6
tubing through a shorting disk at the top. The in-
RG-17/U 52 0.66 0.87 29.5
ner conductor of the cable is connected to a 1 „4-
RG-58/U 54 0.66 0.20 28.5
RG-59/U 73 0.66 0.24 21.0
RG-174/U 50 0.66 0.10 30.8
hard line 50 0.81 0.50 25.0
(1/2-inch) 75 0.81 0.50 16.7
hard line 50 0.81 0.75 25.0
(3/4-inch) 75 0.81 0.75 16.7


coaxial capacitor 1. A somewhat uncommon, but
highly effective, capacitor that uses two telescop-
ing sections of tubing. It works because there is a
certain effective surface area between the inner
and the outer tubing sections. A sleeve of plastic
dielectric is placed between the sections of tub-
ing. This allows the capacitance to be adjusted by
sliding the inner section in or out of the outer sec-
tion. Coaxial capacitors are especially useful in
antenna systems for tuning and/or impedance
matching. Their values are generally from a few
122 coaxial capacitor • code


picofarads up to about 100 pF. 2. A short length and a small high-frequency speaker mounted
of coaxial cable that is used as a capacitor rather concentrically, the smaller within the larger.
than a transmission line because of the inherent When used with a crossover network, this ar-
capacitance between its center conductor and rangement provides fairly good wide-range audio-
braid. See COAXIAL CABLE. frequency response, and saves physical space,
coaxial cavity A cavity consisting of a cylindrical compared with the use of separate speakers.
metal chamber housing a central rod. The cavity coaxial stub 1. A length of coaxial cable acting as
can be tuned to resonance by means of a piston. a branch to another coaxial cable. Commonly
coaxial connector A device used to splice coaxial used for impedance matching. 2. A length of
line or to connect a coaxial line to a transmitter, coaxial cable, usually cut to 1 „4 or 1 „ 2 wave-
receiver, or other piece of apparatus. length, and connected across a coaxial transmis-
sion line to act as a WAVETRAP. Commonly used
to reject strong interfering signals.
coaxial switch A switch designed to connect and
disconnect, or to interchange, coaxial cables in a
transmission line without disturbing the charac-
teristic impedance of the line.
coaxial tank A tank circuit consisting of a rod
within a cylinder. The tank is usually tuned by a
small variable capacitor connected between the
rod and cylinder at one end of the combination.
Generally used at ultra-high frequencies (UHF).
coaxial-tank oscillator A stable, self-excited oscil-
Female Male
lator that uses a COAXIAL TANK. Also see
CONCENTRIC-LINE OSCILLATOR.
coaxial connector
coaxial transistor A transistor in which a semi-
conductor wafer is mounted centrally in a metal
cylinder (the base connection) and is contacted
coaxial diode A semiconductor diode housed in a
on opposite faces by the emitter and collector
cylindrical metal shell acting as one contact, and
whiskers, which are axially mounted.
provided with a recessed, concentrically mounted
coaxial transmission line A transmission line
end pin, which serves as the other contact.
that is a COAXIAL CABLE.
coaxial driver See COAXIAL SPEAKER.
coaxial wavemeter A type of absorption waveme-
coaxial filter 1. A filter that uses a coaxial cable as
ter in which the tunable element is a section of
a tuned circuit. 2. A filter designed to be used in
coaxial line (i.e., a metal cylinder surrounding a
a coaxial transmission line.
metal rod). An internal short-circuiting disk is
coaxial jack A female receptacle or connector,
moved along the cylinder to connect its inner wall
whose concentric terminals have the same spac-
to selected points along the rod™s length, thereby
ing as a male coaxial-cable connector designed to
varying the resonant frequency. The instrument
fit it.
is useful at microwave frequencies.
coaxial line A signal transmission line consisting
cobalt Symbol, Co. A metallic element. Atomic
of COAXIAL CABLE.
number, 27. Atomic weight, 58.94.
coaxial-line frequency meter A microwave ab-
cochannel interference Interference between sim-
sorption wavemeter (see WAVEMETER) with in-
ilar signals transmitted on the same channel.
put and output receptacles for insertion into a
Cockcroft-Walton accelerator A proton accelera-
coaxial line.
tor in which nuclei of hydrogen atoms are given
coaxial-line oscillator See CONCENTRIC-LINE
high velocity through a straight tube by a high dc
OSCILLATOR.
voltage.
coaxial loudspeaker See COAXIAL SPEAKER.
codan Any of several muting (SQUELCH) systems.
coaxial plug A male connector whose concentric
In particular, a squelch circuit that suppresses
terminals have the same spacing as a female
noise in a sensitive receiver equipped with auto-
coaxial cable connector designed to fit it.
matic gain control (AGC). The receiver is quiet
coaxial receptacle A coaxial connector, such as a
until a carrier of predetermined strength is re-
coaxial jack or plug. Receptacles are installed in
ceived. The name is an acronym for carrier-
equipment, whereas plugs are usually attached
operated device antinoise.
to the end of coaxial cables.
codan lamp A lamp that alerts a radio operator
coaxial relay A relay designed to connect and dis-
that a signal of satisfactory strength is being re-
connect, or to interchange, coaxial cables in a
ceived. Also see CODAN.
transmission line without disturbing the charac-
code 1. A set of symbols for communications (e.g.,
teristic impedance of the line.
the Morse code of radiotelegraphy and wire teleg-
coaxial speaker Also called coaxial driver and coax-
raphy in which dots and dashes correspond to
ial loudspeaker. A large low-frequency speaker
123
code • coherence


letters, numbers, and marks of punctuation). 2. coding sheet A form on which program instruc-
In a computer program, symbolically represented tions are written prior to input.
instructions. 3. ENCODE. codiphase radar A radar system that uses beam
codec In encoding and decoding equipment, a forming, signal processing, and a phased-array
coder/decoder, usually in a single package and antenna.
operating at 8 kHz for an input signal with a codistor A voltage-regulating semiconductor de-
passband of 3100 Hz (300 to 3400 Hz). vice.
code character 1. The representation of character coefficient 1. A factor in an indicated product.
in a particular code form. 2. A sequence of dots Thus, in 4y, 4 is the coefficient of y. 2. A param-
and dashes in the Morse code. eter that indicates a specific characteristic of
code conversion The translation of a coded signal some component or device (e.g., COEFFICIENT
from one form of code to another. OF COUPLING or COEFFICIENT OF REFLEC-
coded decimal digit A number expressed in bi- TION).
nary form (computer code), that is, in terms of ze- coefficient of coupling Symbol k. The ratio of MU-
ros and ones only. TUAL INDUCTANCE between two inductors to
code-directing characters Characters added to a the maximum possible (theoretical) value of mu-
message to indicate how and where it is going. tual inductance. This ratio is always greater than
coded program See PROGRAM. or equal to 0 (no coupling between inductors),
coded signal 1. A wire- or radiotelegraph signal in and less than or equal to 1 (perfect coupling be-
which secrecy is achieved by using letters in ci- tween inductors).
pher groups, instead of straight language. 2. coefficient of current detection See CURRENT-
SCRAMBLED SIGNAL. DETECTION COEFFICIENT.
coded stop See PROGRAMMED HALT. coefficient of reflection A measure of the amount
code elements The smallest identifiable parts that of electromagnetic field reflected in a transmis-
compose a digital code. For example, in computer sion line from the load feed point. The coefficient
code, the elements are ones and zeroes (high and of reflection is equal to the square root of the re-
low logic states); in Morse code, they are dots and flected power divided by the forward power.
dashes. coercive force The demagnetizing force required
code holes In a punched card or tape, holes repre- to remove residual magnetism from a material.
senting data. coercivity See COERCIVE FORCE.
code line A written computer program instruction. cogging Nonuniform rotation of a motor armature.
code machine Any one of several devices for The velocity increases as an armature coil enters
recording or reproducing code signals. the magnetic field and decreases as it leaves the
code position The part of a data medium (e.g., field.
card row) reserved for data. coherence In electromagnetic radiation, a condi-
code-practice oscillator A simple keyed audio os- tion in which all the wavefronts are in phase. This
cillator intended for practicing Morse code. results in high energy concentration, and makes
coder 1. In computer operations, a person who possible the long-distance transmission of in-
prepares instructions from flow charts and proce- frared, visible light, and ultraviolet, because the
dures devised by a programmer. 2. A device that rays are almost perfectly parallel. It also makes
delivers coded signals. possible the extreme radiation intensity charac-
code receiver A radiotelegraph receiver. teristic of some LASER devices.
code ringing A method of ringing a telephone sub-
scriber in a predetermined manner to convey a
certain message.
Same frequency
code segment The instruction part of computer
same phase
storage associated with a process. Compare
DATA SEGMENT and DUMP SEGMENT.
code set The collection of codes representing all of Time
the characters in a language.
code speed See KEYING SPEED.
Amplitude




code transmitter 1. A radiotelegraph transmitter.
Time
2. A tape-operated keyer for wire telegraphy or ra-
diotelegraphy.
code word See PHONETIC ALPHABET CODE
WORD.
Time
coding 1. Performing the service of a CODER. 2.
Writing instructions for a digital computer; a part
of programming.
coding check A pencil-and-paper verification of a
routine™s validity. coherence
124 coherent bundle • cold resistance


coherent bundle A bundle of optical fibers, such coil, preventing unwanted inductive coupling to
that the individual fibers are in the same relative other components.
positions at either end of the bundle. coincidence The simultaneous occurrence of two
coherent carrier A carrier that agrees in frequency or more signals. Compare ANTICOINCIDENCE.
and phase with a reference signal. coincidence amplifier An amplifier that delivers
coherent electroluminescent device See LASER an output signal only when two or more input sig-
DIODE. nals occur simultaneously.
coherent light Visible light in which the phase re- coincidence circuit See AND CIRCUIT.
lationship between successive waves is such that coincidence counter A circuit or device, such as a
the beam consists of parallel rays that provide a gate, that delivers an output pulse only when two
high concentration of energy. Also see LASER. or more input pulses occur simultaneously; the
coherent-light radar See COLIDAR. output pulses go to a device that counts them.
coherent oscillator In a radar system, an oscilla- coincidence detector See AND CIRCUIT.
tor that provides a COHERENT REFERENCE. coincidence gate See AND GATE.
coherent-pulse operation Pulse operation charac- coincident-current selection Selection of a mag-
terized by a fixed phase relationship between netic core (in a core memory or similar device) by
pulses. applying two or more currents simultaneously.
coherent radiation Radiation characterized by coin shooting Searching for coins and similar
COHERENCE. small, buried metallic objects using a METAL LO-
coherent reference A stable reference frequency CATOR.
with which other signals are phase locked for co- coke A porous material obtained from the de-
herence. structive distillation of coal. It is valued for the
coherent transponder A transponder in which the production of carbon components for electron-
frequency and phase of the input and output sig- ics, such as dry-cell electrodes and motor
nals have a fixed relationship. brushes.
coil A long conductor or group of conductors wound cold 1. Pertaining to an electrical circuit, compo-
into a tight helical package, often in several layers nent, or terminal that is at ground potential. 2. A
on a cylindrical form. This takes advantage of the term denoting a bad solder joint. 3. Pertaining to
resulting concentration of magnetic flux, maximiz- an unheated electrode or element. See COLD
ing the inductance that can be obtained in a com- CATHODE.
ponent of limited physical size. Further increases cold alignment The alignment of a tracking sys-
in inductance can be realized by the use of ferro- tem (especially of its tuned circuits) when the sys-
magnetic core materials. See also INDUCTOR. tem is not in operation, as when transistor power
coil antenna See LOOP ANTENNA. is off. Also called QUIET ALIGNMENT.
coil checker An alternating-current (ac) meter or cold cathode 1. In an electron tube, a cathode that
simple bridge for checking inductors. Such in- emits electrons without being heated. 2. A cath-
struments usually only indicate inductance val- ode electrode operated at a temperature below
ues, but some list readings of resistance or ambient temperature.
approximate inductor Q factor. cold chamber An enclosure in which electronic
coil dissipation The power wasted in a coil as equipment can be tested at selected, precise low
heat. Generally, this dissipation or loss is propor- temperatures. Compare OVEN.
tional to the resistance of the coil, and to the cold flow The (usually gradual) change in the di-
square of the current passing through the coil. mensions of a material, such as plastic in a
coil form The insulating support around which an molded part.
air-core coil is wound. cold junction In a thermocouple system, an auxil-
coil loading The insertion of one or more inductors iary thermocouple connected in series with the
into a transmission line or antenna element, for hot thermocouple, and immersed in ice or oper-
the purpose of impedance matching, alteration of ated at ambient temperature.
the resonant frequency, or both. cold light Light produced without significant heat,
coil magnification factor The Q factor of an in- as from the ionization of a gas by a high voltage
ductor. Generally given by the ratio XL/RL, where (as in neon bulbs and fluorescent lamps), or by
XL is the inductive reactance of the coil in ohms, electroluminescence, bioluminescence, cathodo-
and RL is the resistance of the coil in ohms. luminescence, or a similar phenomenon.
coil neutralization See INDUCTIVE NEUTRALIZA- cold pressure welding Welding sometimes used in
TION. the fabrication of electronic equipment, in which
coil resistance The resistance of a coil (inductor), the metal parts to be joined are pressed together
as distinct from its reactance. It is almost entirely tightly to the point of deformation, whereupon
the result of ohmic loss in the wire from which they become welded.
the coil is manufactured. cold resistance The resistance of an unheated
coilshield A metal can designed to provide efficient electronic component. Compare HOT RESIS-
electrostatic and electromagnetic shielding of a TANCE.
125
cold rolling • collector voltage


cold rolling A method of manufacturing an induc- collector efficiency In a bipolar transistor circuit,
tor core so that the magnetic grains are all ar- the ratio of ac power output to dc collector-power
ranged lengthwise. input.
cold solder joint A solder joint in which insuffi- collector family For a bipolar transistor, a group
cient heat has been applied, resulting in a bad of collector current versus collector voltage
connection. curves. Each is plotted for a particular value of
cold spot 1. An area of a circuit or component base current (common-emitter circuit) or emitter
whose temperature is ordinarily lower than that current (common-base circuit).
of the surrounding area. 2. A node of current or
voltage. Compare HOT SPOT.




}
IC
cold weld A welded joint produced by means of
COLD PRESSURE WELDING.
colidar An optical radar system using unmodu-
lated, coherent (laser-produced) light. The term is
Various
an acronym for coherent light detection and
values
ranging.
of




Collector current
collate In data processing, to produce an ordered
base
set from two or more similarly ordered sets (as voltage
punched cards). or
collator In a punched-card system, a device that current
collates (see COLLATE) punched cards. (EB or
collector 1. In a bipolar transistor, the electrode IB)
toward which emitted current carriers travel. 2.
In a Klystron, the final electrode toward which
electrons migrate after passing through the
buncher and catcher. 3. In an iconoscope, a
cylindrical electrode around the circumference of EC
Collector voltage
the tube, which gathers and conducts away the
electrons released by the mosaic. 4. The final (tar-
get) electrode in a backward-wave or traveling- collector family
wave tube. 5. A computer program segment that
collates compiled segments so that they can be
loaded into the computer. collector junction In a bipolar transistor, the
collector capacitance 1. Symbol, CC. The capaci- junction between collector and base layers.
tance of the collector junction in a bipolar tran- collector mesh In a cathode-ray storage tube, a
sistor. 2. The capacitance of the collector flat, fine wire screen that attracts and conducts
electrode in a Klystron, iconoscope, backward- away the secondary electrons knocked out of the
wave tube, or traveling-wave tube. storage mesh by the electron beam.
collector current 1. Symbol, IC. The current flow- collector multiplication In a bipolar transistor,
ing in the collector circuit of a bipolar transistor. an increase in the number of electrons at the col-
Also see AC COLLECTOR CURRENT and DC lector electrode, caused by a momentary alter-
COLLECTOR CURRENT. 2. Current flowing in ation of the charge density of the collector
the collector circuit of a Klystron, iconoscope, junction by injected carriers reaching the junc-
backward-wave tube, or traveling-wave tube. tion.
collector-current cutoff See COLLECTOR CUT- collector resistance In a bipolar transistor, the in-
OFF. ternal resistance of the collector junction. See AC
collector cutoff In a bipolar transistor, the condi- COLLECTOR RESISTANCE and DC COLLECTOR
tion in which the collector current is cut off (i.e., RESISTANCE.
reduced to the residual value). Also see CUTOFF collector ring 1. A rotating, brush-contacted ring
CURRENT. electrode connected to one end of a coil in an ac
collector cutoff current See CUTOFF CURRENT. generator. 2. A similar ring which, with a brush,
collector-diffusion isolation A method of mak- serves as a connection to a rotating element, as in
ing integrated circuits that contain bipolar a signal-gathering system. 3. The collector elec-
transistors. Provides electrical separation of trode in an iconoscope.
the transistors in a semiconductor integrated collector transition capacitance The capacitance
circuit. between the collector and base of a bipolar tran-
collector dissipation Symbol, PC. In a bipolar sistor under normal operating conditions. This
transistor, the power dissipation of the collector capacitance has a limiting effect on the operating
electrode. The collector dc power dissipation is frequency of a bipolar device.
the product of collector current and collector volt- collector voltage Symbol, VC. In a bipolar transis-
age: PC = VC IC. tor, the voltage on the collector electrode. See AC
126 collector voltage • color fringing


COLLECTOR VOLTAGE and DC COLLECTOR zontal blanking pedestal in the composite color
VOLTAGE. signal.
collimated rays Electromagnetic waves made par- color carrier See CHROMINANCE SUBCARRIER.
allel or nearly parallel. This can be done by colorcast A color television broadcast.
means of a reflector, a lens, or a laser. color code 1. A system that uses colored stripes or
collimation 1. The process of rendering electro- dots to mark the nominal values and other char-
magnetic rays parallel. 2. Adjustment of the line acteristics on capacitors, resistors, and other
of sight of an instrument, such as a level or tran- components. 2. A code that represents the vari-
sit. ous frequencies being used by radio-control mod-
collimation equipment Optical-alignment equip- elers in competition, and used on flags attached
ment. to transmitters, for example, as a safeguard
collimator A device for producing parallel rays of against jamming.
light or other radiation. In electronics, the most color coder See COLOR ENCODER.
common example is a dish antenna. color contamination In a color television system,

<<

. 7
( 42)



>>