Wiley Electrical and Electronics Engineering Dictionary

266 Pages·2004·31.182 MB·English

by  Kaplan, Steven M.

WILEY ELECTRICAL AND
ELECTRONICS ENGINEERING
DICTIONARY
Steven M. Kaplan
Lexicographer
IEEE PRESS
WILEY-
INTERSCI ENCE
A JOHN WILEY & SONS, INC., PUBLICATION
Copynght 0 2004 by John Wiley & Sons, Inc. All rights reserved.
Published by John Wiley & Sons, Inc., Hoboken, New Jersey.
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Kaplzn, Steven M.
Wiley Electrical and Electronics Engineering Dictionary
ISBN 978-0-471-40224-4
PREFACE AND NOTES ON THE USE OF THIS
DICTIONARY
This dictionary has over 35,000 entries, each of which occupies a place in one or more of
the many areas of expertise encompassed by electrical and electronics engineering. All
available sources were consulted, seeking to ascertain the exact manners in which each
term is currently utilized. Textbooks, handbooks, treatises, instruction manuals, theses, ar-
ticles, reports, Usenet postings, and so on, were researched during the process of selecting
the terms and writing their definitions, with a good number of entries having multiple pro-
vided connotations.
The Internet was used extensively throughout this project, and if one or more persons or
entities used a given technical term in the areas covered by this dictionary, there is a decent
chance it was taken into consideration. If any given words or phrases were used frequently
by multiple people, in varied settings, and when referring to serious endeavors, there is a
pretty good chance it can be found in this dictionary. Even so, some terms that continue to
appear may not be found here. If a user feels .that a given word or phrase not found in this
dictionary should be added to a future edition, or wishes to otherwise comment on this
book, an email may be sent to the author at: [email protected].
There are no special rules for the use of this dictionary. The user simply looks up the de-
sired term to find its definition, plus other practical information when appropriate. When
a word or phrase is the same as another, this is clearly stated so as to easily find the
definition.
This dictionary could not have been prepared without the contributions of George J.
Telecki, Associate Publisher at John Wiley & Sons. He had the idea for this dictionary,
suggested the approach and format, and throughout the project provided inestimable sup-
port and guidance.
This dictionary has been prepared within the exquisite nature settings of Northwestern
Austria. Mr. Wolfgang Gieljer is the person who determined that I should be allowed to
perform my work as an author in this wonderful country. I am tremendously grateful to
him for kindly providing me with the opportunity to live here.
Steven M. Kaplan
Austria, Europe
October, 2003
V
Table of Contents
Preface and Notes on the Use of This Dictionary 3
a - aΩ 1
b - bytes per second 54
c - Czochralski technique 88
d - dysprosium phosphide 163
e- - ezine 222
f - fW 273
g - GΩ 308
h - Hz 328
i - IXC 356
j - JVM 398
k - kΩ 401
l - LZW compression 406
m - MΩ 441
n - nΩ 494
O - ozone 521
p - PΩ 547
Q - QWERTY keyboard 617
r - RZ encoding 623
s - systray 676
t - TΩ 769
U - UXGA 814
v - VXML 829
w - WYSIWYG 851
x - XY recorder 870
y - YUV color model 873
z - Zulu Time 875
Greek Letters Utilized in the Dictionary 879
Symbols 880
Numbers 881
A
a 1. Symbol for atto-. 2. Symbol for acceleration. 3. Abbre- A/V connector Abbreviation of audiohide0 connector.
viation of year. a/v inputs Abbreviation of audiolvideo inputs, or audiovis-
A 1. Symbol for ampere. 2. Symbol for gain. 3. Symbol for ual inputs.
mass number or nucleon number. A/V inputs Abbreviation of audiohide0 inputs, or audiovis-
AIB box Abbreviation of A/B switch box. ual inputs.
A/B switch A switch used in an A/B switch box. a/v outputs Abbreviation of audiolvideo outputs, or audio-
AIB switch box A switch box with two outputs, A and B. visual outputs.
Each output is manually selected by the user. May be used, AIV outputs Abbreviation of audiolvideo outputs, or audio-
for instance, to connect two peripherals to a computer. Also visual outputs.
spelled AB switch box. Its abbreviation is A/B box. A-weighted noise level Same as A-weighted sound level.
A-B test A qualitative test performed by alternating sounds, A-weighted sound level A sound level which is weighted in a
images, or the like. For example, two pairs of speakers wish manner that more closely matches the ear’s response. Such
to be compared, so each is connected to the same amplifier, weighting reduces the influence of lower and higher fre-
and the same music source is played. The two sets of quencies relative to the middle frequencies, and is usually
speakers are then heard alternately. Also spelled AB test. expressed in dBA units. Also called A-weighted noise
A battery A battery which supplies current to the filaments of level.
electron tubes. Also known as filament battery. A- Symbol A minus.
a.c. Same as ac. A+ Symbol for A plus.
A channel In a two-channel stereo component. such as an A4 Same as A440.
amplifier, the left channel. A440 An internationally recognized standard for musical
a/d Abbreviation of analog to digital. pitch, whose frequency is 440 Hz. It is the musical note of
A/D Abbreviation of analog to digital. A above middle C. Also called A4.
ald converter Abbreviation of analog-to-digital converter. aA 1. Abbreviation of attoampere. 2. Abbreviation of
abampere.
A/D converter Abbreviation of analog-to-digital converter.
AA Abbreviation of auto answer.
A display In radars, an oscilloscopic display which plots time
or distance in the horizontal plane versus the scanned object, AAC Abbreviation of augmentative and alternative com-
which appears in the vertical plane. Also called A scope, A munication.
indicator, A scanner, or range-amplitude display. AAL Abbreviation of ATM Adaptation Layer.
A-h Abbreviation of ampere-hour. AAR Abbreviation of automatic alternate routing.
A indicator Same as A display. AAS Abbreviation of atomic absorption spectroscopy.
A-law A standard utilized to convert an analog input, usually ab- A prefix which identifies units conforming to the cgs
voice, into digital form using pulse code modulation. Cur- system. Seen, for example, in abvolt.
rently, it is used in most of the world, except in North Amer- AB box Same as AIB box.
ica and Japan, where the mu-Law standard is used. AB power pack 1. A source of current in battery-operated
Alm Abbreviation of ampere per meter. electron tubes, consisting of the A battery and the B battery.
A/m’ Abbreviation of ampere per square meter. 2. A unit which supplies A and B direct-current voltages
from an AC source.
A min Abbreviation of ampere-minute.
AB switch Same as A/B switch.
A minus The negative terminal of an A battery. Its symbol is
A-. AB switch box Same as A/B switch box.
A-N radio range Same as AN range. AB test Same as A-B test.
A-N range Sanie as AN range. abampere The unit of current in the cgs system. There are 10
amperes in an abampere. Its abbreviation is aA.
A negative Same as A minus.
abandoned call 1. A call that is terminated by the calling
A plus The positive terminal of an A battery. Its symbol is
party before being answered. 2. A call that is terminated by
A+.
the calling party before being completed. For example, that
A positive Same as A plus. in which a caller waiting to speak to a representative ends
A power supply Same as A supply. the call before being attended,
A Programming Language Same as APL. abandoned site A Web site that is no longer maintained, but
A scan Same as A scanner. which is still available for viewing. It is essentially the same
as a ghost site, except the former generally provides a
A scanner Same as A display.
statement to the effect.
A scope Same as A display.
abandoware Software that is no longer considered by the
A station Within the loran radio navigation system, one of
publisher or vendor to be worth selling or supporting.
two transmitting stations, the other being the B station. The
abbreviated dialing A system employing circuitry which
A station is the control station in this pair.
permits dialing with fewer operations than ordinarily neces-
A supply A source which supplies current to the filaments of
sary. An example is speed dialing.
electron tubes. Also called A power supply.
abbreviated ringing Ringing that is initiated at the arrival of
A-t Abbreviation of ampere-turn.
an incoming call, but which stops within a determined nuni-
a/v Abbreviation of audiovisual, or audio video. ber of seconds whether the calling party has terminated the
A/V Abbreviation of audiovisual, or audio video. call or not.
alv connector Abbreviation of audiolvideo connector. abc Same as ABC.
ABC 2 absolute pitch
ABC 1. Abbreviation of automatic brightness control. absiemens The unit of conductance in the cgs system. There
2. Abbreviation of automatic bass compensation. 3. Ab- are lo9 siemens in an absiemens. Its abbreviation is aS. An
breviation of Atanasoff-Berry Computer. absiemens is the same as an abmho, but the former is the
abcoulomb The unit of electrical quantity in the cgs system. preferred term.
There are 10 coulombs in an abcoulomb. Its abbreviation is absolute 1. Independent of arbitrary parameters. 2. In com-
aC. puter programming, a mathematical function that always
abcoulomb centimeter The unit of electric dipole moment in yields a positive number.
the cgs system. Its abbreviation is aCcm. absolute accuracy Accuracy as measured in reference to an
abend Abbreviation of abnormal end. A complete and unex- absolute standard.
pected program or system halt. Caused by a program defi- absolute address A specific memory location. It is an ad-
ciency or a hardware failure. Also called abnormal termi- dress from which relative addresses may be derived. Also
nation, crash (I), or bomb. called real address (l), actual address (I), direct address,
ABEND Same as abend. machine address, or specific address.
aberration In optics, the inability of an optical lens to pro- absolute altimeter An instrument which measures and indi-
duce a perfect correlation between an object and its resulting cates altitude above a reference level, such as a given ter-
image. This can be due to various factors, including the rain, by the utilization of radio, radar, laser, sonic, or capaci-
physical properties of the lens. Types of optical aberration tive technology.
include curvature, astigmatism, spherical aberration, and absolute code Program code which uses absolute addresses.
chromatic aberration. Also called optical aberration. absolute coding Coding which uses absolute addresses.
abfarad The unit of capacitance in the cgs system. There are absolute delay 1. The time difference between two synchro-
lo9 farads in an abfarad. Its abbreviation is aF. nized signals. 2. Within the loran radio navigation system,
abhenry The unit of inductance in the cgs system. There is the time difference between the last signal sent from the A
10." henry in an abhenry. Its abbreviation is aH. station and the next signal from the B station.
ABI Abbreviation of application binary interface. absolute efficiency The ratio between the actual output signal
Abilene A high-speed backbone used, for instance, for Inter- of a transducer and the value of an ideal transducer under
net2. the same conditions.
abmho Same as absiemens. absolute electrometer An attracted-disk electrometer in
which the attraction between the metals disks is balanced
abnormal end Same as abend.
against the force of gravity.
abnormal glow discharge A current discharge in a gas tube
absolute error 1. The difference between the measured value
that causes the cathode area to be completely surrounded by
and the real value. 2. The absolute value of the difference
a glow. Under these conditions the voltage drop increases
between the measured value and the real value, thus always
proportionally to the current.
resulting in a positive value.
abnormal propagation Radio-wave propagation which is
absolute gain Same as absolute gain of an antenna.
adversely affected by unstable atmospheric conditions.
Within these circumstances the waves are unable to travel absolute gain of an antenna For a hypothetical antenna that
their normal path through space, thus interfering with com- transmits and receives uniformly in all directions, the gain in
munications. any specific direction. Also called absolute gain.
abnormal reflections Sharply defined reflections of radio absolute humidity The grams of water vapor per cubic meter
waves at frequencies above the critical frequency of the ion- of moist air. The proportion of moistness does not vary with
ized layer of the ionosphere. When they occur in sporadic temperature. This contrasts with relative humidity, which
E-layers of the ionosphere they are called sporadic-& re- depends more on how much water air can hold at a given
flections. temperature.
abnormal termination Same as abend. absolute index of refraction 1. The ratio of the phase veloc-
ity of a wave in free space, to the phase velocity of the same
abnormal triggering Activation of a switching device by a
wave in a given medium. Also called index of refraction
source other than that of the designated triggering signal.
(l), or refractive index (1). 2. The ratio of the phase veloc-
abohm The unit of resistance, impedance, or reactance in the ity of light in free space, to the phase velocity of light in a
cgs system. There is ohm in an abohm. Its abbreviation given medium. Also called index of refraction (2), or re-
is an. fractive index (2).
abohm centimeter The unit of resistivity in the cgs system.
absolute instruction A computer instruction that specifies an
abort 1. To intentionally terminate a process before it is operation and causes it to be executed.
meant to end. 2. To interrupt a process before it is meant to absolute magnetometer A device which measures the
end.
strength and direction of a magnetic field without using
above the fold The part of a Web page that is visible without other magnetic instruments.
scrolling, while the part that requires scrolling to be seen is
absolute maximum rating The extreme operating or envi-
below the fold. Content above the fold is usually consid- ronmental conditions beyond which a device can malfunc-
ered to be more important than that below.
tion or become damaged.
abrasion resistance The extent to which materials can with- absolute measurement A measurement made utilizing inter-
stand mechanical wear on their surface. If a surface is ex- nationally accepted base units, such as time measured in
posed to a wiper arm or a brush. for example, this must be seconds, or mass expressed in kilograms.
taken into account.
absolute path A file pathname that starts with the drive letter,
abrupt junction A pn junction with an irregular transition
leads through the directories, and ends with a full file name.
region between the p-type and n-type semiconductors.
For example: C:\Documenfs\Retninders\Todu~.xyz. Also
ABS resin Abbreviation of acrylonitrile-butadiene-styrene known as access path, full path, search path, or filespec.
resin.
absolute pitch The pitch of a tone expressed in vibrations per
abscissa In a two-coordinate system, the horizontal coordi- second, thus independently of other tones. This contrasts
nate. The ordinate is the vertical coordinate. Its symbol is with relative pitch, which is based on relationships between
x. or X. Also called x-coordinate. tones.
absolute pressure 3 absorption peak
absolute pressure Pressure relative to that found in an abso- absorptance For a body or material which is irradiated, the
lute vacuum. This contrasts with gauge pressure, which is proportion of the incident radiation absorbed. Put another
measured relative to the ambient pressure. way, absorptance = (1 - transmittance).
absolute pressure sensor Same as absolute pressure trans- absorptiometer 1. An instrument utilized for measuring the
ducer. concentration of a substance by its differential absorption of
absolute pressure transducer A pressure transducer with an monochromatic radiation. 2. An instrument used for meas-
internal chamber kept as close as possible to a perfect vac- uring absorption.
uum, so as to provide absolute pressure readings. Also absorption 1. The energy or matter retained or dissipated
called absolute pressure sensor. when one medium is exposed to another. 2. The absorption
absolute programming Programming using absolute code, of only certain frequencies of electromagnetic or acoustic
which specifies specific physical storage locations. waves by a surface, object, or region. Also called selective
absolute scale 1. Same as absolute temperature scale. 2. A absorption (1). 3. The absorption of only particles with
standard scale utilizing internationally accepted base units, given energies by a surface, object, or region. Also called
such as time measured in seconds, or mass expressed in selective absorption (2). 4. The absorption of only certain
kilograms. particles by a surface, object, or region. Also called selec-
absolute standard A standard which is independent of arbi- tive absorption (3).
trary parameters. absorption band In spectroscopy, the interval of wavelengths
absolute system Same as absolute system of units. which are absorbed by molecules. This contrasts with that
ofatoms, which have an absorption line.
absolute system of units A system used for measurement of
physical quantities using internationally accepted fundamen- absorption circuit A circuit utilized to absorb power at spe-
tal units. All other units and internationally accepted sys- cific frequencies. Such circuits may be used, for example to
tems of units are based on these fundamental, or absolute, enhance the selectivity of a receiver.
units. Currently, the fundamental, or base, SI units are: the absorption coefficient Also called absorption ratio, absorp-
second, the kilogram, the meter, the ampere, the Kelvin, tion factor, absorption constant, absorptive power, ab-
the mole, and the candela. Also called absolute system. sorptivity, or extinction coefficient. 1. The proportion of
absolute temperature Temperature according to the therrno- certain wavelengths or energy retained by a medium to
dynamic temperature, Kelvin, or Rankine scales. When us- which another has been exposed. 2. The proportion of cer-
ing any of these scales, a reading of zero represents absolute tain wavelengths or energy retained by a medium to which
zero. another has been exposed, per unit of area, thickness, or
absolute temperature scale A temperature scale whose value length.
of zero degrees equals absolute zero. The thermodynamic absorption constant Same as absorption coefficient.
temperature, Kelvin, and Rankine scales are absolute tem- absorption current In a dielectric, the component of the
perature scales. Also known as absolute scale (1). dielectric current which is proportional to the inflow of
absolute uniform resource locator Same as absolute URL. charge.
absolute unit 1. A unit which does not incorporate arbitrary absorption dynamometer A device which measures power,
parameters. 2. A unit within the absolute system of units. and that uses a brake to absorb and dissipate the mechanical
absolute URL Abbreviation of absolute uniform resource energy being measured.
locator. A URL which specifies the full path to the location absorption factor Same as absorption coefficient.
of a given page, document, or resource. A relative URL
absorption fading Gradual reductions in the strength of radio
provides abbreviated information based on an absolute URL.
waves as they are propagated through the atmosphere. The
absolute vacuum A hypothetical space which contains no losses are mostly due to absorption by the ionosphere.
matter, and whose absolute pressure is defined as zero. Free
absorption frequency meter An instrument for measuring
space approaches an absolute vacuum. Also called perfect
frequencies utilizing a tunable circuit and resonance indica-
vacuum, or vacuum (1).
tor. Part of the energy measured is absorbed, hence the ab-
absolute value The magnitude of a quantity always expressed sorption component of its name.
as a positive number, regardless of the sign or direction. For
absorption line 1. In spectroscopy, the specific wavelength
example, the absolute value of -12.3 or 12.3 is the same,
that each species of atom absorbs. This contrasts with those
namely 12.3.
of molecules, which have an absorption band. 2. Any cx-
absolute-value computer A computer that processes the
tremely narrow range of absorbed wavelengths within the
magnitudes of variables independently of their algebraic
electromagnetic spectrum.
sign.
absorption loss In the transmission of electromagnetic waves,
absolute-value device A device which produces an output
losses due to dissipation or the conversion of energy. For
signal with a fixed polarity that is equal in magnitude to the
example, a conversion of electrical energy into heat. Also
input, regardless of the polarity of the input.
called absorption losses. When the loss is because of ab-
absolute viscosity A measure of the resistance a flowing fluid sorption by the atmosphere, it is called atmospheric ab-
has to any change in shape. Also called dynamic viscosity. sorption.
absolute zero The temperature at which atoms and molecules absorption losses Same as absorption loss.
have the least possible kinetic energy. It is the zero of the
thermodynamic temperature scale, and represents a reading absorption meter 1. An instrument that measures the amount
of 0 in the Kelvin or 0" in the Rankine scales, respectively, of light that is transmitted through a transparent medium.
which in turn is equal to approximately -273.15" Celsius, or 2. An instrument which measures absorption.
approximately -459.67" Fahrenheit. absorption modulation A method of amplitude modulation
absorbed wave 1. A radio wave which is absorbed by the which employs a variable-impedance device which is cou-
ionosphere. 2. A radio wave which is absorbed by a given pled to the output circuit of the transmitter, to absorb power
medium. from the carrier wave. Also called loss modulation.
absorber A medium or material which absorbs energy or absorption peak 1. A peak in the absorption of electromag-
matter from another which has been exposed to it. Used, for netic waves due to absorption loss. 2. Within spectroscopy,
instance, in shielding or filtering. a wavelength with maximum absorption of the incident elec-
absorption ratio 4 AC magnetic biasing
tromagnetic rays. These are used in the identification of at- AC-3 Abbreviation of Audio Coding-3. The coding utilized
oms, molecules, and other chemical entities. in the Dolby surround sound format. Also called Dolby
absorption ratio Same as absorption coefficient. AC-3.
absorption spectrophotometer In spectroscopy, an instru- AC-AC power converter A converter that changes from one
ment used to measure the relative intensities of light absorp- AC power source to another of a different voltage.
tion by a sample. These levels of absorption determine the AC adapter A converter that changes the AC available from
intensities of the spectral lines and bands. an electrical outlet into a low-voltage source of DC power.
absorption spectroscopy An instrumental analysis technique Utilized, for instance, to provide for the energy requirements
in which rays are irradiated through a substance which ab- of portable devices such as notebook computers, in cell
sorbs them selectively. The frequencies and their corre- phone chargers, and so on. Also called AC power adapter,
sponding absorptions are then analyzed. or power adapter.
absorption spectrum The display or graph produced by a AC bias Same as AC magnetic biasing.
spectroscope when analyzing a substance. The image is cre- AC circuit A circuit which carries AC.
ated as rays are irradiated through the material, some of AC component In a complex wave containing AC and DC
which are absorbed. The lines and spaces are then charted components, the AC constituent.
according to the level of absorption versus frequency.
AC coupling A circuit coupling which allows passage of AC
absorption trap A parallel-tuned circuit utilized to reduce signals, while blocking DC signals.
interfering waves by absorbing them. Also called absorp-
ac/dc Same as ACIDC.
tion wavetrap.
AClDC Pertaining to electrical equipment which can use
absorption wavemeter An instrument for measuring frequen-
either AC or DC power sources.
cies and wavelengths utilizing a tunable circuit and reso-
AC-DC converter A circuit or device that changes AC to
nance indicator. Part of the energy measured is absorbed,
DC.
hence the absorption component of its name. When cali-
brated to read frequencies, also called absorption fre- AC/DC motor A motor that runs on AC or DC. Also called
quency meter. universal motor.
absorption wavetrap Same as absorption trap. AC-DC power converter A circuit or device that changes
AC power to DC power.
absorptive power Same as absorption coefficient.
AC dump The complete removal of AC from a component or
absorptivity Same as absorption coefficient
system.
abstract class In object-oriented programming, a class util-
AC equipment Electrical equipment which can only use an
ized to define sub-classes. No objects may be created in an
AC power source.
abstract class. This contrasts with a concrete class, within
which objects may be created. AC erase Same as AC erasing.
abstract data type In computer programming, a data struc- AC erasing Tape erasing employing AC. Also called AC
ture that is defined by a programmer. It is more generalized erase.
than a data type, and its internal form requires special func- AC erasing head An erasing head which employs AC to
tions to be accessed, as it is hidden from the other structures create an alternating magnetic field which erases the tape.
of the program. An abstract data type may refer, for in- The rapid inversions of the magnetic field effectively ran-
stance, to an object class in object-oriented programming. domize the magnetic particles on the tape to accomplish this
Its abbreviation is ADT. task.
abstraction In object-oriented programming, the process of AC frequency The frequency at which AC reverses its polar-
determining the essential components of an object. ity, expressed in hertz. Its direction is reversed 60 times per
abT Abbreviation of abtesla. second in most of North and South America and 50 times
per second in the greater part of the rest of the world. That
abtesla The unit of magnetic flux density or magnetic induc-
is, the AC frequency is 60 and 50 Hz respectively.
tion in the cgs system. There is tesla in an abtesla.
Also known as gauss. Its abbreviation is abT. AC generator 1. A machine which converts mechanical
power into AC power. Such machines are usually rotary.
abvolt The unit of potential difference in the cgs system.
2. Any device which generates AC power.
There is 10' volt in an abvolt. Its abbreviation is aV.
AC induction motor An AC motor in which the electric
abvolt per centimeter The unit of electric field strength in the
current flowing through the rotor is induced by the AC flow-
cgs system.
ing in its stator. The power source is connected only to the
abwatt The unit of power in the cgs system. There is lo'
stator. Also called induction motor.
watt in an abwatt.
AC line A line which supplies AC power. Also called AC
abWb Abbreviation of abweber.
power line.
abweber The unit of magnetic flux in the cgs system. There
AC line filter A filter for lines supplying AC. Unwanted
is weber in an abweber. Its abbreviation is abWb.
components, such as noise, are removed. An example is a
Also known as maxwell.
power-line filter.
AC 1. Abbreviation of alternating current. Electric current
AC line voltage The AC voltage supplied by an AC power
which alternates at regular intervals. Its direction is reversed
line. This may vary from country to country, and consists of
60 times per second in North America and 50 times most
two nominal voltages. The lower number is primarily for
elsewhere, that is, 60 and 50 Hz respectively. Every cycle
lighting and small appliances, while the larger number is for
the current starts at zero, peaks, returns to zero, reaches the
heating and large appliances. In Canada and the United
maximum in the opposite direction, goes back to zero, and
States, for example, the nominal voltages are approximately
so on. The average current during any complete cycle is
115/230. Also called line voltage (I), or power-line volt-
zero. 2. Pertaining to, or utilizing AC (1). 3. Abbreviation
age (1).
of access concentrator.
AC magnetic biasing Application of a high-frequency AC to
aC Abbreviation of abcoulomb
the recording head of magnetic tape. This improves per-
Ac Chemical symbol for actinium. formance, as seen for example, in expanded frequency re-
ac Same as AC. sponse and reduced noise. Also called AC bias.
AC meter 5 acceptable reliability level
AC meter A meter designed for measuring AC signals. accelerating potential The high positive potential applied to
AC motor A machine which converts AC into mechanical the accelerating electrode, which accelerates the electrons in
power. An example is an induction motor. the beam.
AC noise Also called power-line noise. 1. Electromagnetic accelerating relay A relay which helps to start or further
interference occurring in AC lines. 2. Electromagnetic inter- accelerate a motor.
ference, occurring in AC lines, which adversely affects the accelerating time 1. The time that elapses between a voltage
performance of electronic components. being initially applied to a motor, and the motor running at
AC plate resistance In electron tubes, the opposition the plate full speed. 2. The time required for a motor or mechanical
circuit offers to a small increase in plate voltage. Measured device to reach its operational speed.
in ohms. Also called dynamic plate resistance. accelerating voltage The high positive voltage applied to the
AC power 1. Same as AC power supply. 2. The power accelerating electrode, which accelerates the electrons in the
provided by an AC power supply. Expressed in watts. beam.
AC power adapter Same as AC adapter. acceleration The rate at which velocity increases with respect
to time. Its symbol is a.
AC power line Same as AC line.
acceleration space In an electron tube, the space just beyond
AC power source Same as AC power supply.
the electron gun, where electrons are accelerated to the de-
AC power supply A power supply whose output is AC. sired velocity.
Examples include transformers, inverters, and oscillators.
acceleration switch A switch that is actuated when exposed
Also known as AC power (I), AC power source, or AC
to an acceleration greater than a determined threshold. A
supply.
simple acceleration switch may consist of a spring and an
AC resistance The combined resistance offered by a device in
electric contact.
a high-frequency AC circuit. It includes, among others, DC
acceleration time The time required for a motor or mechani-
resistance, and resistance due to dielectric and eddy-current
cal device to reach its operational speed.
losses. Also known as high-frequency resistance, RF re-
sistance, or effective resistance. acceleration voltage In an electron tube, the voltage between
the cathode and the accelerating electrode.
AC supply Same as AC power supply.
accelerator 1. A device which causes the acceleration of
AC transmission The transmission of power using AC. This
something. 2. Same as accelerating electrode. 3. In com-
is well suited for power that will be used a great distance
puters, a hardware device which accelerates and/or enhances
from the generating station. A high voltage is used, which is
the performance of a system or subsystem. 4. A device,
then reduced by transformers as needed.
such as a linac or cyclotron, in which charged particles are
AC voltage A voltage that alternates at regular intervals.
greatly accelerated to achieve high energies. Also called
Every cycle the voltage starts at zero, peaks, returns to zero,
particle accelerator, or high-energy particle accelerator.
reaches the maximum in the opposite direction, and goes
accelerator board An expansion board, such as a graphics
back to zero. The average voltage during any complete cy-
accelerator, which makes a computer faster. Also known as
cle is zero. Also known as alternating voltage.
accelerator card.
ACC Abbreviation of automatic color control.
accelerator card Same as accelerator board.
accelerated aging Same as accelerated life test.
accelerometer An electromechanical transducer which meas-
accelerated aging test Same as accelerated life test.
ures acceleration, and whose output is a voltage that is pro-
accelerated graphics port A graphics port that is geared portional to the acceleration it is subjected to. Such a device
towards a faster and higher quality display of video and may incorporate, for instance, piezoelectric elements which
three-dimensional images. It achieves this, in part, by ena- generate a voltage that varies linearly with the mechanical
bling the graphics controller to directly access the main strain experienced.
memory, as opposed to having to go through the system’s accentuation Also called emphasis. 1. Highlighting of a
PCI bus. Its abbreviation is AGP. specific frequency or band of frequencies through amplifica-
accelerated life test Operation of a device beyond its maxi- tion. 2. The process of selectively amplifying higher fre-
mum ratings in order to accelerate its aging process. This is quencies of an audio-frequency signal before transmission,
helpful in determining the effects of time, and in calculating or during recording. The utilization of accentuation fol-
the expected life of the device and its components. Also lowed by deaccentuation may help improve the overall sig-
known as accelerated aging, or accelerated aging test. nal-to-noise ratio and reduce distortion, among other bene-
accelerated service test A test made under extreme condi- fits. Also called preemphasis.
tions to more rapidly ascertain the characteristics, capabili- accentuator A circuit which serves to accentuate a specific
ties, and limitations of a device or component. frequency or band of frequencies. For example, automatic
accelerated test 1. A test made under extreme conditions in bass compensation boosts low frequencies in an audio high-
an effort to ascertain the effects of time or continued use on fidelity system at low-volume settings. Also called accen-
a component, circuit, device, piece of equipment, or system. tuator circuit.
2. The test of an electric cable by subjecting it to a voltage accentuator circuit Same as accentuator.
twice that normally carried. acceptable angle Same as acceptance angle (2).
accelerated testing A series of tests made under extreme acceptable quality level The minimum percentage of output
conditions in an effort to ascertain the effects of time, or that meets the pre-established criteria for quality. Con-
continued use, on a component, circuit, device, piece of versely, the highest permissible amount of defects propor-
equipment, or system. tional to the overall production of a product. Its abbrevia-
accelerating anode Same as accelerating electrode. tion is AQL.
accelerating electrode In an electron tube, such as a klystron acceptable reliability level The minimum level of reliability
or CRT. the electrode to which a high positive voltage is ap- that is acceptable for a system or component. May be ex-
plied, which accelerates the electrons in the beam. Also pressed, for example, as a given number of failures per thou-
called accelerating anode. or accelerator (2). sand hours of normal operation. Its abbreviation is ARL.