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describing radiation or pickup characteristics (as
for antennas, microphones, loudspeakers), a
small peak aligned in a direction other than that
of the main lobe.
no-field release In the starting box for a shunt mo-
tor, the electromagnet that normally holds the
arm in full-running position; it is connected in se-
ries with the field winding. When the field current
is lost, the arm is released, disconnecting the ar-
mature for safety. Compare NO-VOLTAGE RE-
LEASE.
noise 1. A random-frequency current or voltage
signal extending over a considerable frequency
spectrum and having no useful purpose, unless
it is intentionally generated for test purposes.
2. Dissonant, interferential sound; unlike harmo-
nious sound, it is disagreeable. 3. In audio oper-
ations, unwanted hiss and/or hum. 4. Extra bits noise-canceling microphone A microphone that
or bytes that must be removed from digital data discriminates against background sounds. It is
before it can be useful. usually directional and relatively insensitive, re-
noise abatement The elimination or reduction of quiring the user to talk directly into it at close
noise intensity”especially a measure in a pro- range.
gram concerned with noise pollution in the envi- noise clipper A biased-diode circuit used as an
ronment. automatic noise limiter. The device cuts off all
noise analysis The measurement of the amplitude signals above a predetermined amplitude on the
and spectral distribution of noise and the deter- theory that noise peaks are high-level transients
mination of its character. in an otherwise uniform signal. Noise is reduced
noise analyzer An instrument for evaluating the at the sacrifice of system reproduction fidelity.
nature of noise in a communications system. See, noise criteria An expression for the level of ambi-
for example, NOISE METER. Noise analyzers are ent acoustic noise.
sometimes adapted for vibration analysis. noise current Noise-generated current.
478 noise-current generator • noise-reducing antenna


noise-current generator A noise generator that noise generator A device for generating precise
supplies a useful current. Compare NOISE- amounts of noise voltage for test purposes.
VOLTAGE GENERATOR. noise grade 1. The relative level of radio-
noise digit A digit (usually zero) generated during frequency background noise, over all electro-
normalization of a floating-point number. See magnetic frequencies, in a particular geographic
NORMALIZE. location. The noise grade is generally lowest
noise diode A reverse-biased semiconductor diode near the poles and highest near the equator.
that produces a standard noise voltage. 2. The mathematical function of relative electro-
noise elimination The nearly complete removal of magnetic noise intensity versus latitude and
noise effects from a system. Noise can never be longitude.
eliminated altogether because the movement of noise immunity The degree to which a circuit or
electrons and atoms generates some electrical device is insensitive to extraneous energy”espe-
and thermal noise. However, in some digital sys- cially noise signals.
tems, the effects of noise can be almost totally noise-improvement factor Abbreviation, NIF. For
overcome. Compare NOISE SUPPRESSION. a radio receiver, the ratio SNi/SNo, where SNi is
noise equivalent power Abbreviation, NEP. The the input signal-to-noise ratio and SNo is the out-
power that produces an rms signal-to-noise ratio put signal-to-noise ratio.
of 1 in a detector. noise killer 1. See AUTOMATIC NOISE LIMITER.
noise factor For a circuit, especially a communica- 2. See NOISE FILTER. 3. See NOISE BLANKER.
tions receiver or weak-signal amplifier, the ratio noiseless alignment See VISUAL ALIGNMENT.
R1/R2, where R1 is the signal-to-noise power ratio of noise level 1. The amplitude of ambient electrical
an ideal circuit, and R2 is the signal-to-noise ratio of noise generated outside an electronic system of
the circuit under test. Compare NOISE FIGURE. interest. 2. The amplitude of electrical noise gen-
noise figure The NOISE FACTOR of a circuit, ex- erated in an electronic system of interest. 3. The
pressed in decibels. If N is the noise factor ex- intensity of ambient acoustic noise.
pressed as a ratio, then noise figure NdB can be noise limiter See AUTOMATIC NOISE LIMITER.
determined by NdB = 10 log10N. noise margin In a binary logic circuit, the differ-
noise filter A filter designed to suppress noise that ence between operating and threshold voltages.
would otherwise enter an electronic circuit (e.g., a noise-measuring set See NOISE METER.
power-line noise filter). noise meter An instrument for measuring acous-
noise floor 1. In a receiver, the level of noise in mi- tic noise level. It consists essentially of a sensi-
crovolts that determines the weakest signal that tive, multirange voltmeter provided with a
can be heard or accurately received. 2. In a spec- microphone, amplifier, and attenuators. The me-
trum analyzer, the level of noise that determines ter scale reads noise level directly in decibels.
the weakest signal that will be visibly displayed.


µ‘
Mike Amp.
Amplitude axis
Readable signals



Frequency noise meter
axis
noise power The power component of a noise
signal.
noise power ratio The ratio of noise power at the
output of a circuit (such as a receiver) to the noise
power at the input.
Noise
noise pulse A random short-duration noise burst
floor
whose amplitude exceeds the average peak noise
level.
noise quieting In a radio receiver, the reduction
(in decibels) of background noise, with respect to
Signals below Do not appear
a signal of interest.
noise floor in display
noise ratio See NOISE POWER RATIO.
noise-reducing antenna A receiving antenna hav-
ing a balanced transmission line and usually
some form of noise-balancing system for reducing
electrical noise picked up by the antenna.
noise floor, 2.
479
noise reduction • nominal value


noise reduction See NOISE SUPPRESSION. nominal bandwidth 1. For a filter, the difference
noise residue The residual output (see NULL fc2 fc1, where fc1 is the nominal lower cutoff fre-
VOLTAGE, 1) of a balanced bridge, caused en- quency and fc2 is the nominal upper cutoff fre-
tirely by noise. quency. 2. For an allocated communication
noise silencer A noise-limiting circuit that re- channel, the total bandwidth, including upper
moves noise-pulse transients with little or no ef- and lower guard frequencies. 3. The intended and
fect on the signal from which the noise is specified bandwidth of a given channel, regard-
removed. Compare NOISE CLIPPER. less of the bandwidth of the signal on that fre-
noise source See NOISE GENERATOR. quency at any given time.
noise spike See NOISE PULSE.
noise suppression 1. In communications, the re-
Channel
duction of noise amplitude to a level that is non-
X




Amplitude
competitive with desired signals. 2. In audio Channel
Y
recording and reproduction, reduction of un-
wanted noise (e.g., hiss) to the greatest extent
possible without degrading the fidelity of the de-
sired audio. Compare NOISE ELIMINATION.
noise suppressor A device for eliminating electri- Freq.
cal noise or reducing its amplitude. See, for ex- Nominal Nominal
bandwidth bandwidth
ample, AUTOMATIC NOISE LIMITER and NOISE
BLANKER.
nominal bandwidth, 2
noise temperature At a given frequency, the tem-
perature of a passive system that has the same
noise power per unit bandwidth as that observed nominal capacitance The rated (“label”) value of a
at the terminals of a device under test. capacitor. Also see NOMINAL VALUE.
noise voltage The voltage component of an electri- nominal current The rated (“nameplate”) value of
cal noise signal. required current or of current output. Also see
noise-voltage generator A signal generator that NOMINAL VALUE.
supplies an alternating-current waveform con- nominal horsepower The rated (“nameplate”)
taining random-frequency pulses of relatively horsepower of a machine, such as a motor. Also
uniform distribution over a given frequency spec- see NOMINAL VALUE.
trum. Compare NOISE-CURRENT GENERATOR. nominal impedance The rated impedance of a cir-
noisy mode During normalization of a floating- cuit or device. Also see NOMINAL VALUE.
point number, the generation of digits, excluding nominal inductance The rated (“label”) value of a
zero, as part of the fixed-point part (see NOR- coil™s inductance. Also see NOMINAL VALUE.
MALIZE). nominal line pitch In a television raster, the aver-
NOL 1. Abbreviation of National Ordnance Labora- age center-to-center separation between adjacent
tory. 2. Abbreviation of Naval Ordnance Laboratory. lines.
no-load current 1. Output-electrode current (e.g., nominal line width 1. For a television raster, the
drain, plate, or collector current) when a device is factor 1/n, where n is the number of lines per
not delivering output to an external load. 2. Cur- unit width for the direction in which the lines
rent flowing in the primary winding of an un- progress. 2. In facsimile, the average center-to-
loaded transformer. center separation of scanning or recording lines.
no-load losses Losses in an unloaded transformer nominal power factor The rated (“nameplate”)
(see NO-LOAD CURRENT, 2). value of power factor of a device. Also see NOMI-
no-load speed The rotational speed of an unloaded NAL VALUE.
motor. nominal power rating The rated (“nameplate”)
no-load voltage The open-circuit output voltage of value of power output, power drain, or power dis-
a power supply, amplifier, generator, or network. sipation. Also see NOMINAL VALUE.
nominal 1. Named, rated, or specified. The nominal nominal Q The rated (“nameplate”) value of Q of a
value of a speaker, for example, might be 8 ohms, capacitor, inductor, transformer winding, or tank
even though the actual impedance value depends circuit. Also see NOMINAL VALUE.
on the frequency of the applied signal. 2. Approx- nominal rating See NOMINAL, 1, 2.
imate, and specified as a typical example only, for nominal resistance The rated (“label”) value of a re-
the purpose of identifying the operating or value sistor or similar device. Also see NOMINAL VALUE.
range. For example, an automotive circuit might nominal speed The highest speed of a data-
have a nominal rating of 12 volts”even though it processing unit or system, disregarding slowdowns
can be operated at 10 volts to 14.6 volts. because of factors other than computational op-
nominal band In a facsimile signal, the waveband erations.
extending between zero and the maximum fre- nominal value A named, specified, rated, or la-
quency of modulation. beled value, given without reference to tolerance.
480 nominal value • nonharmonic oscillations


This can differ significantly from the actual value. nondirectional antenna An antenna that displays
For example, the nominal value of a capacitor equally intense radiation or equally sensitive re-
might be 100 pF; but if the tolerance is ±10 per- ception in all directions within a specified plane.
cent, the actual capacitance might be any value An example is a vertical dipole antenna, which is
between 90 pF and 110 pF. nondirectional in the horizontal plane.
nominal voltage 1. The rated (“nameplate”) value nondirectional microphone A microphone that
of required voltage or of voltage output. Also see responds equally well to sound from any direc-
NOMINAL VALUE. 2. In a cell or battery, the MID- tion; an omnidirectional microphone.
POINT VOLTAGE. nondissipative load A purely reactive load. In
nomogram See ALIGNMENT CHART. such a load, the only power consumed is that
nomograph See ALIGNMENT CHART. which is dissipated in the inherent resistance
nomography The geometric representation of a (losses) of the load.
mathematical function or relation by means of nondissipative stub A stub that exhibits only slight
alignment charts. losses; it consumes no power, except that dissi-
nonaccountable time The period during which a pated in small, inherent losses. Also see STUB.
computer system is unavailable to the user (be- nonelectrical Not electrical in nature. The term is
cause of a power outage, for example). commonly used to designate the mechanical
nonarithmetic shift See LOGICAL SHIFT. parts of electromechanical systems, such as
nonblinking meter A digital meter that does not robots and servomechanisms.
alternate, or oscillate, between two different val- nonelectrolyte A substance that does not ionize in
ues when the measured parameter is between water solution. Compare ELECTROLYTE.
two discrete values. Instead, the display is nonelectronic meter A meter that uses no elec-
rounded off to the nearest value, and the display tronic devices (such as transistors, liquid crys-
remains at that value continuously. tals, light-emitting diodes, or integrated circuits).
nonblocking system In a telephone communica- Also called conventional meter.
tions network, a system that ensures a circuit nonequivalence operation See EXCLUSIVE-OR
will be completed when necessary. That is, at no OPERATION.
time is it impossible for a connection to be made. nonerasable storage In digital-computer and
Under conditions of extremely heavy usage, the data-processing operations, storage media that
quality of communications might be degraded, cannot be erased under ordinary circumstances.
but the connection will not be cut off. A common example is CD-ROM (compact-disk
nonbridging contact In a switch or relay, a mov- read-only memory).
able contact that leaves one stationary contact nonferrous metal A metal or alloy that does not
before contacting another. contain iron, and is not related to iron in the
nonchargeable battery A primary battery (i.e., one sense that it is not attracted to magnets.
that cannot ordinarily be recharged). An example nonflammable Pertaining to a material that is re-
is a battery of common zinc-carbon or alkaline sistant to burning.
cells. nonharmonic frequency A frequency that has no
noncoherent Pertaining to electromagnetic radia- integral numerical relationship to another fre-
tion in which the wave disturbances are not all quency of interest. Compare HARMONIC FRE-
precisely aligned in frequency and phase. QUENCY.
nonconductor See DIELECTRIC. nonharmonic oscillations Parasitic oscillations
noncontact temperature measurement The use that do not occur at the fundamental frequency
of infrared or optical electronic equipment to nor at any harmonic frequency of an oscillator or
measure the temperature of bodies without amplifier in which they appear.
touching them.
noncorrosive flux A solder flux that does not cor-
Fundamental
rode the metals to which solder is applied.
signal
noncrystalline Pertaining to materials that pos-
Relative attenuation (dB)




sess none of the characteristics of crystals. Com- Nonharmonic
0
pare CRYSTALLINE MATERIAL. oscillations
nondestructive read In digital computer and Harmonics
20
counter operation, the process of reading data
without erasing it as a result. The name is also
40
applied to the readout device.
nondestructive test Abbreviation, NDT. A test
60
that does little or no irreversible harm to the test
0 2 4 6 8 10
sample. Compare DESTRUCTIVE TEST.
Relative frequency
nondeviated absorption Absorption that slows
waves by a negligible amount; also, normal sky-
wave absorption. nonharmonic oscillations
481
nonillion • nonoscillating detector


nonillion The number 1030, so called because causes different parts of the signal to be amplified
when written out, the number contains nine or transmitted by different amounts; therefore,
groups of three zeros (following the first 1000). the amplitude variations in the output signal dif-
noninductive capacitor A wound capacitor in fer from those in the input signal.
which the edges of one of the spiral windings are nonlinear inductor See SATURABLE REACTOR.
connected together to minimize the inductance of nonlinearity 1. The condition of being NONLIN-
the roll. Compare INDUCTIVE CAPACITOR. EAR. In an amplifier, this means that the output
noninductive resistor A wirewound resistor con- signal is not a faithful reproduction of the input
structed so that the magnetic field of the coil is signal, and distortion occurs. 2. A measure of the
self-canceling. Therefore, the inductance is prac- extent to which a circuit is nonlinear. Expressed
tically eliminated. as a percentage of peak-to-peak full-scale output,
noninterlaced scanning In the display of a video the maximum extent to which the output differs
image, the presentation of all the raster lines in a from a perfect reproduction of the input.
single scan. It is commonly used in cathode-ray- nonlinearity error An error in received signals re-
tube (CRT) computer monitors. This process min- sulting from nonlinearity in one or more of the
imizes “jerkiness” in rapidly moving images. stages in the communications circuit.
noninverting connection Connection to the non- nonlinear mixing The mixing of signals as a result
inverting input of a differential or operational am- of the nonlinear response of a device (such as a
plifier. Also see NONINVERTING INPUT. Compare semiconductor diode operated in its square-law
INVERTING CONNECTION. region) through which they are passed simultane-
noninverting input In a differential or operational ously. Also see MIXER and MIXING.
amplifier, the input that provides an output sig- nonlinear network A circuit that produces distor-
nal in phase with the input. Compare INVERTING tion in an input waveform; the output and input
INPUT. waves are not related by a linear function.
noninverting transponder In a communications nonlinear quantizing A method of signal quantiz-
satellite, a transponder in which the downlink ing in which the intervals are not all the same size
band is “rightside-up” in frequency relative to the or duration.
uplink band. That is, the highest downlink fre- nonlinear resistor A resistor whose value
quency corresponds to the highest uplink fre- varies with applied voltage. Also see VOLTAGE-
quency, and the lowest downlink frequency DEPENDENT RESISTOR.
corresponds to the lowest uplink frequency. nonlinear response Any response for which the
Compare INVERTING TRANSPONDER. Also see corresponding plot is not a straight line; doubling
DOWNLINK, TRANSPONDER, UPLINK. the independent variable, for example, does not
nonionic 1. Possessing none of the properties of double the dependent variable.
ions. 2. Electrically neutral. nonloaded Q See UNLOADED Q.
nonionizing radiation Electromagnetic radiation nonmagnetic 1. Possessing no magnetism. 2. In-
that does not cause ionization of gases under a capable of being magnetized.
given set of conditions. Examples: radio signals, nonmathematical Pertaining to materials and
television signals, and visible light. methods that rely upon physical description and
nonlinear 1. Pertaining to components, circuits, or qualitative procedures instead of mathematical
devices in which the instantaneous output signal development, prediction, and quantitative proce-
amplitude is not directly proportional to the in- dures.
stantaneous input signal amplitude. The graph of nonmetal An elemental material devoid of the prop-
instantaneous output versus instantaneous in- erties exhibited by metals (e.g., luster, good ductil-
put is a curve, not a straight line. Example: ity, electrical conductivity, heat conductivity, and
CLASS-C AMPLIFIER. 2. Pertaining to compo- malleability). Examples: carbon, phosphorus, sul-
nents, circuits, or devices in which a specified fur. Compare METAL and METALLOID.
value is not directly proportional to some other nonmetallic conduction Collectively, ionic con-
specified value. Example: NONLINEAR CAPACI- duction in liquids and gases, conduction in
TOR. dielectrics by small leakage currents, and
nonlinear bridge See VOLTAGE-SENSITIVE thermionic conduction in a vacuum.
BRIDGE. nonmicrophonic Without microphonic properties,
nonlinear capacitor A capacitor whose value e.g., a nonmicrophonic integrated circuit does not
varies nonlinearly with applied voltage. Also see produce electrical ringing when physically struck.
VOLTAGE-VARIABLE CAPACITOR, 1, 2. nonnumeric character A character that is not a
nonlinear coil See SATURABLE REACTOR. numeral, i.e., a symbol or letter.
nonlinear dielectric A material (such as pro- nonohmic response 1. Nonlinear resistance or re-
cessed barium-strontium titanate) whose dielec- actance. Compare OHMIC RESPONSE. 2. See
tric constant varies with applied voltage. NEGATIVE RESISTANCE.
nonlinear distortion Distortion caused by nonlin- nonoscillating detector A detector devoid of posi-
ear response of an amplifier or component. This tive feedback action and, therefore, unable to
482 nonoscillating detector • nonsynchronous vibrator


generate a signal on its own. Compare OSCIL- nonrepetitive phenomena See NONRECURRENT.
LATING DETECTOR. nonrepetitive sweep In an oscilloscope, a single
nonplanar 1. Existing in three spatial dimensions. horizontal sweep of the electron beam, initiated
2. Pertaining to a circuit that cannot be fabri- either by the operator or by the signal under ob-
cated on a two-dimensional board without the servation. Also called SINGLE SWEEP. Compare
use of jumper wires. RECURRENT SWEEP.
nonpolar 1. Having no pole(s). 2. Pertaining to nonreset timer A timer that must be reset manu-
atoms that share electrons to complete their ally.
outer shells. 3. Not polarized nor requiring polar- nonresident routine A computer routine not per-
ization. Example: a 100-pF disk ceramic capaci- manently stored in memory. Compare RESIDENT
tor is nonpolar because it can be used in circuits ROUTINE.
without consideration of voltage polarity. nonresonant 1. Pertaining to a resonant circuit or
nonpolar crystal A crystal in which lattice points device operated at some frequency other than one
are identical. of its resonant frequencies. Thus, reactance is
nonpolarized electrolytic capacitor An elec- present at the operating frequency. See RESO-
trolytic capacitor that has no definite negative NANCE. 2. Pertaining to a circuit or device that
and positive terminals and, consequently, can be exhibits pure resistance (without reactance) over
used in alternating-current circuits, as well as in a wide range of frequencies.
direct-current circuits. See also NONPOLAR, 3. nonresonant lines Transmission lines so dimen-
sioned and operated that they do not resonate at
the operating frequency.
Electrolyte
nonresonant load An alternating-current load
paste
that is either purely resistive or is detuned from
the fundamental and harmonic frequencies of the
Oxide
source from which it is operated.
film
nonreturn to zero In the magnetic recording of
digital data, the system in which the current flow-
ing in the write-head coil is sustained (i.e., does
not return to zero) after the write pulse.
Oxide nonsalient pole A nonprojecting (often flush) pole.
film Compare SALIENT POLE.
nonsaturated color 1. Visible light that consists of
energy at more than one wavelength. 2. A color that
contains some white, in addition to the pure color.
Anodes
nonsaturated logic A logic circuit in which tran-
sistors are prevented from saturating. This re-
nonpolarized electrolytic capacitor
sults in higher operating speed than SATURATED
LOGIC using the same transistors.
nonpolarized reactor A saturable reactor in which
nonshorting switch A multiple-throw switch that
the lines of flux produced in the three-leg core by
disconnects one circuit before completing an-
the coils on the two outer legs oppose each other
other; that is, no two poles are ever connected si-
in the center leg. When direct current (dc) is
multaneously.
passed through the coil on the center leg to satu-
nonsinusoidal waveform A waveform whose curve
rate the core, operation remains the same for ei-
cannot be represented by the equation y = c sin
ther dc polarity. Compare POLARIZED REACTOR.
a(x + b), where a, b, and c are constants, y is the
nonpolarized relay See UNPOLARIZED RELAY.
dependent variable (usually instantaneous am-
nonprint code In telegraphy, a code used to start
plitude or frequency), and x is the independent
teleprinter functions excluding printing.
variable (usually time), for any real-number val-
nonreactive circuit A circuit containing pure re-
ues of a, b, and c. Examples: BACK-TO-BACK
sistance only.
SAWTOOTH, SAWTOOTH, and SQUARE WAVE.
nonrechargeable battery See NONCHARGEABLE
The COSINE WAVE is sinusoidal, being a SINE
BATTERY.
WAVE shifted in phase by 90 degrees.
nonrecurrent Pertaining to phenomena that do
nonsymmetrical wave See ASYMMETRIC WAVE.
not repeat periodically. Thus, a single sweep in an
nonsynchronous Unrelated in cyclic quality to
oscilloscope is nonrecurrent.
other such qualities in the system.
nonrecurrent sweep See NONREPETITIVE SWEEP.
nonsynchronous network A communications net-
nonregenerative detector A detector having no
work in which the clocks are not all synchronized.
regenerative feedback. Such a detector is stable,
nonsynchronous vibrator A power-supply vibra-
but relatively insensitive. Compare REGENERA-
tor that is essentially a single-pole, double-throw
TIVE DETECTOR.
switch providing no mechanical rectification.
nonregenerative receiver A radio receiver in
A separate rectifier must be used. Compare
which no local signal whatever is generated.
483
nonsynchronous vibrator • normal-mode rejection


VIBRATOR-TYPE RECTIFIER. Also see VIBRA- normal 1. Pertaining to the most commonly ob-
TOR-TYPE POWER SUPPLY. served set of conditions or parameters. 2. Stan-
nontechnical Pertaining to circuits, devices, sys- dard. 3. Perpendicular; oriented at right angles.
tems, or phenomena described in lay terms, using 4. Pertaining to a NORMAL DISTRIBUTION.
concise graphics and little or no mathematics. An 5. Pertaining to a NORMAL SOLUTION. 6. Pertain-
example is the simplified explanation of the oper- ing to an atom at its lowest energy state. See
ation of a spread-spectrum radio transmitter. NORMAL STATE OF ATOM.
nontonal components See NOISE, 3. normal curve See BELL-SHAPED CURVE.
nontrigger voltage For a thyristor, the maximum normal distribution In a statistical evaluation, a
gate-to-cathode voltage that can be applied with- probability distribution represented by the so-
out triggering the device. The amplitude of inter- called bell-shaped curve. The maximum probabil-
ferential signals, including noise, must be below ity occurs at the 50-percent value.
this level to prevent accidental triggering. normal-distribution curve See BELL-SHAPED
nonuniform field An electric or magnetic field CURVE.
whose intensity is not the same at all points. normal electrode A standard electrode used in
nonvolatile memory Memory whose data is re- electrode-potential measurements.
tained even when power is removed for extended normal fault An unintended path between the hot
periods. This type of memory requires no backup terminal of a load and ground.
power source. The main advantage of this type of normal fault plus grounded neutral fault A com-
memory is the fact that the data is not lost in case bination of NORMAL FAULT and GROUNDED
of a power interruption. Memory should not be NEUTRAL FAULT.
confused with storage. Magnetic, magneto- normal glow discharge In a glow-discharge tube,
optical, or optical disks (including hard drives) are the discharge region between the Townsend dis-
storage media, not memory. Memory data can be charge and the abnormal glow in which current
stored and retrieved much faster than storage increases sharply, but a constant voltage drop is
data, because memory uses no mechanical parts. maintained across the tube.
Also see RANDOM-ACCESS MEMORY, READ- normal impedance A transducer™s input imped-
ONLY MEMORY. Compare VOLATILE MEMORY. ance when the load impedance is zero.
nonvolatile storage A computer storage medium normal induction curve A saturation curve for a
in which the data does not require a source of magnetic material. Also see BOX-SHAPED LOOP
power to be retained. Examples: MAGNETIC and SATURABLE REACTOR.
DISK, MAGNETIC TAPE, and COMPACT-DISK normalize In computer programming, to use float-
READ-ONLY MEMORY. ing-point numbers to modify the fixed-point part
no-op instruction An instruction that commands of a number so that it is within a desired range.
a computer to perform no operation, other than normalized admittance The quantity 1/Zn, where
to proceed to the following instruction. Zn is NORMALIZED IMPEDANCE.
NOR circuit Also called NOT-OR CIRCUIT. In com- normalized frequency The unitless number repre-
puter and control operations, a circuit that deliv- sented by the ratio f/fr, where fr is a reference fre-
ers a zero output signal, except when two or more quency and f is a frequency of interest. Response
input signals are zero. The NOR circuit function plots are sometimes conveniently drawn on the
is the inverse of that of the OR circuit. basis of normalized frequency, the reference (or
NOR gate A gate that performs the functions of a resonant) frequency being indicated as 1, twice
NOR circuit. the reference frequency as 2, etc.
norm The average or ambient condition. normalized impedance A value of impedance di-
vided by the characteristic impedance of a wave-
guide.
normally closed Abbreviation, NC. Pertaining to a
A switch or relay whose contacts are closed when
C the device is at rest. Compare NORMALLY OPEN.
B normally open Abbreviation, NO. Pertaining to a
switch or relay whose contacts are open when the
device is at rest. Compare NORMALLY CLOSED.
A B C normal mode Pertaining to a device or system op-
erated in its usual or most common manner.
0 0 1
normal mode A state of acoustic resonance in an
0 1 0
enclosure, such as a speaker cabinet or a room.
1 0 0 normal-mode rejection Abbreviation, NMR. In a
digital direct-current voltmeter, the level of noise
1 1 0
on the applied voltage that will be rejected by the
instrument. Compare COMMON-MODE REJEC-
TION.
NOR circuit
484 normal position • notch sweep


normal position In a switch or relay, the state of
the contacts when the device is at rest.
0
normal solution A solution, such as an electrolyte,
in which the amount of dissolved material is
chemically equivalent to 1 gram-atomic weight
of hydrogen per liter of the solution. Compare
MOLAR SOLUTION.
10
normal state of atom The condition in which an




Attenuation, dB
atom is at its lowest energy level. For the hydro-
gen atom, for example, the state in which the
electron is in the lowest-energy orbit.
normal-through A feature in an audio PATCH BAY
20
or PATCH PANEL that connects two sockets by
default. The top socket and the one immediately
below it are connected, even when a patch cord is
not plugged into either of them.
30
northern lights See AURORA.
north magnetic pole The north pole of the equiva-
lent bar magnet constituted by the EARTH™S
MAGNETIC FIELD. The north magnetic pole lies
40
close to the geographic north pole. Compare
SOUTH MAGNETIC POLE. 200 800 1400
north pole 1. See NORTH MAGNETIC POLE.
2. The earth™s geographic north pole. 3. See
Audio frequency, Hz
NORTH-SEEKING POLE.
north-seeking pole Symbol, N. The so-called
notch
north pole of a magnet. When the magnet is sus-
pended horizontally, this pole points in the direc-
tion of the earth™s north magnetic pole. Compare ject one frequency or a given band of frequencies
SOUTH-SEEKING POLE. while passing all higher and lower frequencies.
Norton™s equivalent An equivalent circuit based notch antenna An antenna with a slot in the radi-
on NORTON™S THEOREM, replacing a Thevenin ating surface, for the purpose of obtaining a di-
equivalent for a current-actuated device, such as rectional response.
a bipolar transistor. Also see THEVENIN™S THEO- notcher See NOTCH FILTER.
REM. notcher-peaker A circuit or device that can be set
Norton™s theorem With reference to a particular to perform either as a NOTCH FILTER or PEAK
set of terminals, any network containing any FILTER.
number of generators and any number of con- notch filter A circuit that exhibits high attenua-
stant impedances can be simplified to one con- tion at and near a single frequency and little or no
stant-current generator and one impedance. The attenuation at all other frequencies. This type of
equivalent circuit will deliver to a given load the device is used in some radio communications re-
same current that would flow if the output ceivers, and can reduce interference caused by
terminals of the original circuit where short- strong, unmodulated carriers within the pass-
circuited. Compare COMPENSATION THEOREM, band. The notch frequency is adjustable, so that
MAXIMUM POWER TRANSFER THEOREM, the deep null can be tuned to any frequency
RECIPROCITY THEOREM, SUPERPOSITION within the receiver passband. A properly de-
THEOREM, and THEVENIN™S THEOREM. signed circuit can produce attenuation in excess
NOT In binary logic, an operation that changes of 40 dB in the center of the notch. Some sophis-
high to low and vice versa. Also see NAND CIR- ticated types, especially audio designs, can pro-
CUIT, NOR CIRCUIT, NOR GATE, NOT CIRCUIT, vide more than 60 dB of attenuation at the notch
and NOT-OR CIRCUIT. frequency. Audio notch filters employ operational
NOT-AND circuit See NAND CIRCUIT. amplifiers with resistance-capacitance (RC) cir-
notation The way that numbers, quantities, or for- cuits. In some audio notch filters, the notch
mulas are represented (e.g., binary notation, Pol- width (sharpness) and frequency are both ad-
ish notation, and scientific notation). justable. Compare BAND-REJECTION FILTER.
notch A dip in frequency response, typical of a notch gate In radar, a gate that determines the
band-suppression (band-elimination) filter or minimum and maximum range.
other frequency-rejection circuit. Compare notch sweep An oscilloscope sweep that expands
PEAK, 3. only a small portion (notch) of the pattern on the
notch amplifier An amplifier containing a notch screen, leaving the portions on either side of the
filter or other arrangement that permits it to re- notch untouched. Thus, the first dozen or so
485
notch sweep • n-type conduction


cycles might appear at the normal sweep speed, npn transistor A bipolar transistor in which the
the next two cycles expanded, and the remaining emitter and collector layers are n-type semicon-
two or three at normal sweep speed. ductor material, and the base layer is p-type
NOT circuit A logic circuit that provides an output semiconductor material. Compare PNP TRAN-
pulse when there is no input pulse, and vice SISTOR.
versa. Also called COMPLEMENTER, NEGATOR, NP0 Abbreviation of NEGATIVE POSITIVE ZERO.
and INVERTER. NP0 capacitor A fixed capacitor exhibiting temper-
note See BEAT NOTE. ature-compensating ability over a wide tempera-
notebook computer A portable personal com- ture range, in which the coefficient has negative,
puter, also called a laptop computer. It is about positive, and zero values.
the size of a typical three-ring notebook, and gen- NPS Symbol for counts per second.
erally contains a DISKETTE DRIVE, a HARD N radiation X rays emitted as a result of an elec-
DISK, a MODEM, and attachments for peripher- tron becoming an N electron.
als, such as printers. It uses rechargeable batter- NRD Abbreviation of NEGATIVE-RESISTANCE
ies and can be operated for approximately two to DIODE.
six hours between battery charges. N region See N LAYER.
NOT gate A digital circuit that inverts a logical con- NRZ Abbreviation of NONRETURN TO ZERO.
dition”either from high (logic 1) to low (logic 0) or Ns Symbol for number of secondary turns in a
vice versa. Also called an inverter. transformer.
NOT-OR circuit A logical OR CIRCUIT combined ns Abbreviation of NANOSECOND.
with a NOT CIRCUIT. N scan See N DISPLAY.
novelty calculator See SPECIAL-PURPOSE CAL- N scope Colloquialism for a radar set using an N
CULATOR. DISPLAY.
November Phonetic alphabet code word for the let- nsec Alternate abbreviation of NANOSECOND.
Ns/m2 Newton-seconds per meter squared, the
ter N.
novice 1. A beginner class of amateur radio li- unit of dynamic viscosity.
cense. 2. Any beginner or inexperienced practi- n-space A coordinate system in n variables. It is
tioner. generally of mathematical interest. The coordi-
no-voltage release In the starting box for a shunt nates are written (x1, x2, x3, . . . ,xn) and are called
motor, the electromagnet that normally holds the ordered n-tuples.
arm in full-running position. It is connected di- NSPE Abbreviation of National Society of Profes-
rectly across the power line to disconnect the mo- sional Engineers.
tor in the event of power failure. When the arm is NTC Abbreviation of NEGATIVE TEMPERATURE
released, it falls to its off position, thereby pre- COEFFICIENT.
venting burnout that would result if the motor nth harmonic An unspecified harmonic, having a
were left connected to the line in the full-running frequency of n times the fundamental frequency,
position when power resumed. Compare NO- where n is some positive integer. Also see HAR-
FIELD RELEASE. MONIC and HARMONIC FREQUENCY.
noys scale A scale of apparent acoustic noise, nth term An unspecified term in a mathematical
based on a linear function instead of the more sequence or series.
common logarithmic function. NTP Abbreviation of NORMAL TEMPERATURE
Np 1. Symbol for NEPTUNIUM. 2. Abbreviation of AND PRESSURE.
NEPER. NTSC Abbreviation of National Television Stan-
Np Symbol for number of primary turns in a trans- dards Committee.
former. NTSC color signal The color-television signal spec-
n-phase system A polyphase system having n ified by the National Television Systems Commit-
phases. tee. In the signal, the phase of a 3.58-MHz signal
npin transistor A junction transistor having an in- varies with the instantaneous hue of the trans-
trinsic layer between a p-type base and an n-type mitted color, and the amplitude varies with the
collector. The emitter is a second n-type layer on instantaneous saturation of the color.
the other side of the base. NTSC triangle On a chromaticity diagram, a trian-
N plant See NUCLEAR POWER PLANT. gle whose sides encompass the range of colors
n-plus-one address instruction A computer pro- obtainable from the additive primaries.
gram instruction containing two addresses, one NTSC-type generator A special radio-frequency
of which specifies the location of an upcoming in- signal generator for color-television tests. It pro-
struction to be executed. vides separate, individually selected color bars
NPM Symbol for counts per minute. that are fully saturated. The signals are strictly in
npnp device A semiconductor switching device accordance with NTSC standards.
having three junctions. Examples: FOUR-LAYER n-type conduction In a semiconductor, current
DIODE, and SILICON-CONTROLLED RECTI- flow consisting of electron movement. Compare
FIER. Also called pnpn device. P-TYPE CONDUCTION.
486 n-type material • null detector


n-type material Semiconductor material that has nuclear reaction 1. A reaction in which a heavy
been doped with a donor-type impurity and, con- atomic nucleus is split into two or more lighter nu-
sequently, conducts a current via electrons. Ger- clei, with an accompanying release of radiant en-
manium, for example, when doped with arsenic, ergy. Also called NUCLEAR FISSION. 2. A reaction
becomes n-type. Compare P-TYPE MATERIAL. in which two or more light nuclei combine to form
n-type semiconductor See N-TYPE MATERIAL. a heavier nucleus, accompanied by the release of
nuclear battery See ATOMIC BATTERY. radiant energy. Also called NUCLEAR FUSION.
nuclear bombardment In nucleonics, the bom- nuclear reactor 1. A device in which nuclear fis-
barding of the nucleus of an atom with subatomic sion can be initiated and controlled. At the center
particles, usually neutrons. of the reactor is a core of nuclear fuel, such as a
nuclear charge The net positive charge of the nu- fissionable isotope of uranium. The core is sur-
cleus of an atom. rounded by a graphite moderator jacket that is, in
nuclear clock A chronometer based on the rate of turn, surrounded by a coolant jacket; the whole
disintegration of a radioactive material. is surrounded by a thick concrete shield. Neu-
nuclear energy Energy resulting from the splitting tron-absorbing rods are inserted through various
of the nucleus of an atom or from the fusion of walls to different depths in the fuel to control the
nuclei. Also see ATOMIC ENERGY, ATOMIC reaction. Also called atomic pile. 2. A controlled
POWER, NUCLEAR FISSION, NUCLEAR FUSION, nuclear fusion device, not yet perfected, but un-




Y
NUCLEAR REACTOR, and NUCLEUS. der development. It would provide all the benefits
nuclear fission A nuclear reaction resulting from of an atomic pile (fission reactor), but would be




FL
the bombardment of nuclei in the atoms of cer- more efficient and would not produce hazardous
tain radioactive materials. The bombardment radioactive waste.
with neutrons creates two new nuclei (by split- nuclear recoil An observable vibration of an
ting) and several new neutrons that split several atomic nucleus when it disintegrates.
AM
other nuclei, producing still more nuclei and neu- nuclear resonance The condition wherein a nu-
trons, etc. The result is a chain reaction that can cleus absorbs a gamma ray emitted by an identi-
lead to a violent explosion if not checked. Com- cal nucleus.
pare NUCLEAR FUSION. nuclear service robot A remotely controlled (tele-
nuclear force A strong attraction that holds to- operated) robot used for general work in environ-
TE

gether pairs of nucleons in an atomic nucleus. ments where the level of radioactivity is too high
This prevents an electric charge of protons from for humans (e.g., the maintenance of a nuclear
driving the nucleus apart. Nuclear force acts only reactor). It could also be used, if necessary, for
over very minute distances. At greater distances, such tasks as disarming nuclear warheads and
electrostatic repulsion is stronger. cleaning up after a nuclear accident.
nuclear fusion A nuclear reaction resulting from nucleon A proton or neutron in the nucleus of an
the violent collision of the nuclei of the atoms of a atom.
hydrogen isotope (such as deuterium) at ex- nucleonics The branch of physics concerned with
tremely high temperature. The process produces nucleons and nuclear phenomena. The name is
more energy than does NUCLEAR FISSION, and an acronym for nuclear electronics.
leaves no hazardous radioactive waste. nucleon number See MASS NUMBER.
nuclear magnetic resonance An atomic phe- nucleus The center or core of an atom. Contains
nomenon in which a particle, such as a proton, in neutrons, protons, and other particles. The net
a steady magnetic field “flips over” when an alter- electric charge of the nucleus is positive, and is
nating magnetic field is applied perpendicular to equal to the sum of the negative charges of the or-
the steady field. bital electrons of the atom.
nuclear magnetic resonance imaging Abbrevia- null 1. The condition of zero output current or volt-
tion, NMRI. The use of NUCLEAR MAGNETIC age resulting from adjusting or balancing a cir-
RESONANCE effects to produce a picture of inter- cuit, such as a bridge. 2. A local minimum in an
nal body organs. Using computers, three- interference pattern or directivity pattern.
dimensional renditions can be generated. It is null balance In potentiometric-measuring circuits
useful in medicine as a diagnostic aid. for comparing one voltage to another, the balance
nuclear medicine A branch of medicine involving condition in which no current flows through the
the use of radioactive isotopes in diagnosing and galvanometer.
treating disease. A radioactive isotope is put null current In potentiometric-measuring circuits
inside the body and it tends to accumulate in for comparing one voltage to another, the gal-
certain areas. Abnormal concentration of vanometer current remaining at null when the
radioisotopes might indicate abnormal body ac- null point is not fully zero.
tivity in a certain area. null detection Direction finding by means of an
nuclear pile See NUCLEAR REACTOR. antenna with a bidirectional or unidirectional
nuclear power plant A power-generating plant us- null response.
ing a NUCLEAR REACTOR. null detector See BRIDGE DETECTOR.




Team-Fly®
487
null frequency • N zone


numerical code A code having a character set re-
stricted to digits.
numerical control A method of programming
Electron
computer-controlled mechanical devices, used in
shells
some early robots. An automated system in which
number sequences fed to a digital computer
cause it to control machines or processes in a
manufacturing operation.
nV Abbreviation of NANOVOLT.
nW Abbreviation of NANOWATT.
Nucleus nybble A piece of digital information that is larger
than a bit and smaller than a byte. Compare
GULP.
Nylon The trade name for a synthetic fiber-forming
polyamide, useful for electrical insulation.
Nyquist criterion of stability With reference to a
NYQUIST DIAGRAM for a feedback amplifier, the
amplifier is stable if the polar plot of loop amplifi-
cation for all frequencies from zero to infinity is a
closed curve that neither passes through nor en-
nucleus closes the point 1 + j0.
Nyquist diagram A graph of the performance of a
null frequency The frequency at which a fre- reactive feedback system (such as a degenerative
quency-sensitive circuit, such as a Wien bridge or amplifier) that depicts the variation of amplitude
twin-tee network, can be balanced. and phase of the feedback factor with frequency.
null meter See BRIDGE DETECTOR. The plot is polar and accounts for the real and
null method See ZERO METHOD. imaginary components.
null point In a balanced circuit, such as a bridge
or potentiometer, the point of zero output voltage
(Imaginary)
(or current) or minimum output voltage (or cur-
rent). jy
null potentiometer 1. The variable resistor that
constitutes one arm of a four-arm bridge and is
used to balance the bridge. 2. A potentiometric
circuit using the null method to compare one volt-
age with another. Also see POTENTIOMETER, 2.
null setting 1. The setting of a bridge circuit or Phase
other null device that balances the circuit. 2. The
electrical zero setting of an electronic voltmeter.
null voltage 1. In a conventional bridge, the out-
put voltage remaining when the bridge is set for x (Real)
its best null. 2. For a voltage-sensitive bridge, the
input voltage that will produce zero output volt-
age.
number The mathematical representation of a
quantity. It is generally used in electronics to de-
note coefficients, magnitudes, component values,
frequencies, etc.
number cruncher A computer with great compu-
tational power, but one not necessarily able to
process large amounts of data (such as payroll in-
formation).
number system A systematic sequence of num- Nyquist diagram
bers based on a radix and a logical arrangement.
See, for example, BINARY NUMBER SYSTEM and
DECIMAL NUMBER SYSTEM. Nyquist noise rule The power dissipated in a re-
numeral A member of a digit set in a number sys- sistor because of thermal noise at a given fre-
tem. quency. The derivative of frequency, with respect
numerical analysis A mathematical approach to to power, is equal to the absolute temperature
solving problems numerically, including finding times the Boltzmann constant.
the limits of error in the results. N zone See N LAYER.
O 1. Symbol for OXYGEN. 2. Abbreviation of OUT- object program A machine or high-level language
PUT. version of a user™s computer program, as pro-
o 1. Symbol for OUTPUT. (Also, OUT; both are used duced by a compiler.
as subscripts.) 2. Symbol for ORIGIN. object recognition In robotic systems, any
O2 Symbol for OXYGEN. method used to identify specific objects, accord-
O3 Symbol for OZONE. ing to characteristics, such as shape, texture,
OAT Abbreviation of OPERATING AMBIENT TEM- weight, etc. Common schemes use bar-code la-
PERATURE. bels and machine vision. More-complex methods
object code 1. In a computer system, the machine- make use of pattern-recognition programs.
language output of the compiler, directed oblique-incidence transmission Transmission of
to the computer. 2. In a computer, the high-level radio signals via ionospheric reflection.
output of the compiler, directed to the operator. oblique mode In acoustics, a resonance within a
3. The assembly language, directed to the com- room that involves all four walls, the floor, and
piler for translation between machine language the ceiling.
and high-level language and vice versa. oboe A system of radar navigation in which a pair
object language The computer language that a of ground stations measures the distance to an
compiler derives from a high-level (source) lan- airborne transponder beacon and then transmits
guage (such as C++, LISP, etc.); it is usually ma- the information to the aircraft.
chine language, but it can be an intermediate obsolescence-free Pertaining to a design or pro-
code that requires further conversion. cess that is not likely to become obsolete in the
object-oriented graphics Also called vector graph- near future. Compare OBSOLESCENCE-PRONE.
ics. In computer graphics, the use of equations to obsolescence-prone Pertaining to a design or pro-
represent curves in a coordinate plane to define cess subject to being soon outdated. Compare
shapes, rather than defining the shapes pixel-by- OBSOLESCENCE-FREE.
pixel. OBWO Abbreviation of O-TYPE BACKWARD-WAVE
object-oriented language A computer program OSCILLATOR.
that uses on-screen objects, called icons, to rep- o/c Abbreviation of OPEN CIRCUIT.
resent commands. A movable device, such as a occluded gas Gas that has been absorbed or ad-
mouse or trackball, is used to move an arrow or sorbed by solid material, such as glass or metals,
other pointer to the icon; then a button is pressed and that must be eliminated during the evacua-
to carry out the function indicated by the icon. tion of an electronic device, such as a vacuum
object-oriented programming Abbreviation, OOP. tube. Also see OUTGASSING.
A computer programming language that builds occultation 1. The passage of the moon or other
sophisticated programs from basic programs planetary body in front of a more distant celestial
called modules. object, resulting in the cutting off of electromag-


Copyright © 2001 by The McGraw-Hill Companies, Inc.
Click here for Terms of Use.
489
occultation • odometry


netic radiation from that object. 2. The eclipsing octant One-eighth of a circle; therefore, 45 de-
of one object by another. grees, or 0.5 quadrant.
occupied band A frequency band used by at least octave 1. The range of frequencies between a given
one transmitting station regularly. frequency ( f ) and twice that frequency (2f ).
occupied bandwidth For a given emission, the 2. The range of frequencies between a given fre-
continuous band of frequencies (f2 f1) for which quency ( f ) and half that frequency ( f/2).
the mean (average) radiated power above f2 and octave band A band of frequencies one octave wide
below f1 is 0.5 percent of the total mean radiated (see OCTAVE).
power. octave-band noise analyzer A noise analyzer hav-
occupied orbit In an atom, an orbit in which an ing bandpass-filter channels whose center fre-
electron is present. quencies are one octave apart.
Ocean Phonetic alphabet code word for the letter O. octave-band pressure level Sound pressure level
OCR Abbreviation of OPTICAL CHARACTER REC- within an OCTAVE BAND.
OGNITION. octave pressure level See OCTAVE-BAND PRES-
oct Abbreviation of OCTAL. SURE LEVEL.
octal Abbreviation, oct. Based on the number eight. OCTL Abbreviation of OPEN-CIRCUITED TRANS-
See, for example, OCTAL NUMBER SYSTEM. MISSION LINE.
octal digit One of the figures in the group 0 octonary signal An eight-level signaling code.
through 7 used in the OCTAL NUMBER SYSTEM. octonary system See OCTAL NUMBER SYSTEM.
octal notation See OCTAL NUMBER SYSTEM. OD Abbreviation of OUTSIDE DIAMETER.
octal number system The base-eight system of odd-even check A method of checking the integrity
number notation. It uses digits 0 through 7. of data transferred in a computer system, in which
Compare BINARY NUMBER SYSTEM and DECI- each word carries an extra digit to show whether
MAL NUMBER SYSTEM. The octal system is often the sum of ones in the word is odd or even.
used as shorthand for otherwise-cumbersome bi- odd harmonic In a complex waveform, a harmonic
nary numbers. The binary number is separated that is an odd-numbered multiple of the funda-
into groups of three digits from right to left; each mental frequency (e.g., third harmonic, fifth har-
such group is then converted into its decimal monic, etc.). Compare EVEN HARMONIC.
equivalent, with the result being the octal form of odd-harmonic intensification In a complex wave-
the binary number [e.g., binary 111 001 011 = oc- form, emphasis of the amplitude of odd harmon-
tal 713 (111 = decimal 7; 001 = decimal 1; and ics, with respect to that of even harmonics, a
011 = decimal 3)]. property of some multivibrators and nonsinu-
soidal waves.
odd line In a conventional television picture, one
Decimal Octal of the 262.5 odd-numbered horizontal lines
0 0 scanned by the electron beam in developing the
1 1 odd-line field. Compare EVEN LINE.
2 2 odd-line field On a conventional television screen,
3 3 the complete field obtained when the electron
4 4 beam has traced all the odd-numbered lines.
5 5 Compare EVEN-LINE FIELD.
6 6 odd-line interlace See ODD-LINE FIELD.
7 7 odd parity check A computer check for an odd
8 10 number of ones or zeros in digital data.
9 11 Odex Trade name for a series of autonomous
10 12 robots developed by Odetics, Inc. They use legs
11 13 for locomotion. Noted for their ability to maneu-
12 14 ver in places that most robots cannot reach.
13 15 odograph An electromechanical or electronic plot-
14 16 ter that traces the path of a vehicle on a map, or
15 17 on the image of a map as portrayed on a display
16 20 screen.
odometer An electromechanical device that indi-
octal number system
cates the speed of, and distance covered by, a
moving vehicle or robot. Some such devices give a
octal-to-decimal conversion Conversion of num- constant position indication, via mathematical
bers in the octal number system to numbers in integration of the measured velocity (speed and
the more-familiar decimal number system. direction), relative to time. It can function in one,
This is done by expressing the octal number ser- two, or three dimensions.
ially in powers of eight. Thus, octal 12 = (1 — 81) + odometry A method of speed, velocity, and/or po-
(2 — 80) = 8 + 2 = decimal 10. sition sensing. It is commonly used in mobile
490 odometry • ohmic contact


vehicles and mobile robots. The most- by itself (i.e., not connected in a network). Com-
sophisticated systems give a constant indication pare ONLINE.
of position on the basis of a starting point (origin) offline editing In video production, a process in
and mathematical integration of the velocity which copies are made of the original recording;
(speed and direction), with respect to time. It can these copies are edited in a trial-and-error
function in one, two, or three dimensions. scheme to develop the final presentation. Com-
Oe Symbol for OERSTED. pare ONLINE EDITING.
oersted Symbol, Oe. The cgs unit of magnetic field offloading The use of computers and/or robots to
intensity; 1 Oe = 79.58 A/m. Formerly the unit of perform repetitive, mundane tasks, leaving peo-
reluctance. ple free to do more interesting things. Example: a
off-air alarm A device that gives a visible or audi- personal robot that mows the lawn.
ble indication when the carrier of a transmitter is off-on operation See ON-OFF OPERATION.
lost. In its most rudimentary form, the device off period 1. The interval during which an on-off
consists of a radio-frequency relay that actuates circuit or device is off. 2. The time during which
a bell, buzzer, horn, or lamp. an equipment is shut down.
off-center display A radar display whose center offset An imbalance between the halves of a nor-
point does not correspond to the location of the mally symmetrical circuit, such as that of a dif-
antenna. ferential amplifier. Also see OFFSET CURRENT
off-center-fed antenna An antenna in which a and OFFSET VOLTAGE.
feeder is attached to one side of the center point offset adjustment range The change in offset volt-
of the radiator. See, for example, WINDOM AN- age, in millivolts or in microvolts, that can be af-
TENNA. fected by means of the external offset adjustment
off-center feed The connection of a feed line to an circuit(s).
antenna radiator at some point other than the offset current For an operational amplifier, the in-
physical center of the radiator. put current when the offset voltage is zero.
offset voltage For an operational amplifier, the
particular value of direct-current bias voltage re-
»/4 3»/4 quired at the input to produce zero output volt-
age.
off state 1. The condition of an on-off circuit or de-
vice, such as a flip-flop, that is off. Compare ON
STATE, 1. 2. The condition in which a circuit or
device is shut down. Compare ON STATE, 2.
off-state voltage The voltage drop across a semi-
off-center feed
conductor device, such as a diode, rectifier, or
thyristor, when the device is in its normal off
(nonconducting) state. Compare ON-STATE
off delay The interval during which a circuit re-
VOLTAGE.
mains on after the control signal has been
off-target jamming In radio or radar jamming, the
switched off. Compare ON DELAY.
use of a remote jamming transmitter that will not
off-ground 1. An above- or below-ground operating
betray the location of the base station.
voltage. 2. The ground return for a voltage, as de-
off time The period during which no useful work is
fined in 1, not common with the system ground.
being performed, as of equipment when it is not
offhook In a telephone system, the condition in
functioning because of a circuit breakdown.
which the receiver is removed from its receptacle,
OGL Abbreviation of OUTGOING LINE.
or in which the line is otherwise engaged (e.g., a
OGO Abbreviation of orbiting geophysical observa-
fax machine or modem is in use).
tory.
off isolation A measure of the extent to which an
ohm Symbol, „¦. The basic unit of resistance, reac-
´
open switch isolates the output from the input,
tance, or impedance. A resistance of 1 ohm
specified as the output voltage divided by the in-
passes a current of 1 ampere in response to an
put voltage. For percentage, multiply this quan-
applied emf of 1 volt.
tity by 100. The ideal value is zero (or zero
ohmage Electrical resistance or resistivity ex-
percent).
pressed in ohms.
off-limit In a stepping relay, a condition in which
ohm-centimeter A unit of volume resistivity (see
the armature has gone past the limit of its travel.
RESISTIVITY): the resistance of a centimeter
offline 1. In a computer installation, equipment
cube of the material under measurement. Also
that is not controlled by the central processor.
see MICROHM-CENTIMETER.
2. In computers and data processing, operations
ohmic component A resistive or reactive circuit or
that are not under the direct real-time control of
device exhibiting an OHMIC RESPONSE.
a central processor. 3. A computer memory facil-
ohmic contact A usually very-low-resistance con-
ity or device not connected to a central processor.
nection between two materials that provides
4. In personal computing, the use of a computer
491
ohmic contact • oil diffusion pump


bilateral linear conduction. It exhibits none of the
properties of a rectifying junction or a nonlinear
resistance. Zero
ohmic heating 1. Heating caused by current pass- adjust
Range
ing through a resistive material (i.e., I2R losses in
switch
the material). 2. In an electric field, heat gener-
ated by charged particles when they collide with
Unknown
other particles.
resistance
ohmic loss Loss resulting from the direct-current
resistance in a circuit or transmission line.
ohmic region The portion of the response curve of Voltmeter
a negative-resistance device that exhibits positive
mA
(ohmic) resistance. The E-I curve of a tun-
+ ’
nel diode, for example, has two such positive-
slope regions with a negative-slope (negative-
resistance) region between them.


ohmmeter

Nonohmic Ohm™s law The statement of the relationship
(negative-resistance) among current, voltage, and resistance. In a
Current




region direct-current circuit, current varies directly
Ohmic Ohmic with voltage and inversely with resistance: I = E/R,
region region where I is the current in amperes, E is the volt-
age in volts, and R is the resistance in ohms. For
alternating current, Ohm™s law states that I =
E/X = E/Z, where X is reactance and Z is
impedance.
0
Voltage ohms per square The resistance (in ohms) between
two parallel edges of a square of thin-film resis-
ohmic region tance material.
ohms-per-volt A specification that indicates the
ohmic resistance A resistance exhibiting OHMIC sensitivity and impedance of a voltmeter. In gen-
RESPONSE. eral, the higher the rating, the better. When mea-
ohmic response Response that follows OHM™S suring voltage in high-impedance circuits, the
LAW: I = E/R. In strictly ohmic devices, neither rating should be as high as possible. Field-effect-
resistance nor reactance changes with current or transistor (FET) voltmeters and vacuum-tube
voltage. Compare NONOHMIC RESPONSE. voltmeters have the highest ratings.
ohmic value Electrical resistance expressed in oil-burner control An electronic system for start-
ohms, or in multiples or fractions of ohms (kilo- ing and stopping the operation of an oil burner to
hms, megohms, milliohms, etc.) prevent puffback and to interrupt the supply
ohmmeter An instrument for the direct measure- when the flame becomes erratic.
ment of electrical resistance. It usually consists oil calorimeter A calorimeter used to measure
of a milliammeter or microammeter, a battery, power in terms of the rise in temperature of oil
and several switchable resistors having very close heated by the electrical energy of interest.
tolerances. The scale is calibrated in ohms; the oil capacitor A capacitor impregnated or filled
switch selects multiplier factors (e.g., —100, with oil, such as high-grade castor or mineral oil.
—10,000, —1,000,000). The scale is usually re- Also see OIL DIELECTRIC.
versed (i.e., 0 is at the extreme right and “infinity” oil circuit breaker A circuit breaker filled with a
is at the extreme left). high-grade insulating oil for cooling and arc elim-
ohmmeter zero 1. The condition of proper adjust- ination.
ment of an ohmmeter, indicating zero resistance oil-cooled transformer A heavy-duty transformer,
for a direct short circuit. 2. The potentiometer, or through which oil is circulated for heat removal
other control, used for adjusting an ohmmeter to and arc prevention.
obtain a reading of zero with a short circuit. oil dielectric A highly refined oil used as an elec-
ohm-mile A rating meaning 1 mile of wire having a trical insulating material (e.g., between the plates
resistance of 1 ohm. of a capacitor). Familiar examples are castor oil,
ohms adjust The rheostat or potentiometer used to mineral oil, and the synthetic oil chlorinated
set the pointer of an ohmmeter before it is used to diphenyl.
take resistance readings. oil diffusion pump See OIL PUMP.
492 oiled paper • one-lunger


oiled paper Insulating paper impregnated with oil omnidirectional range station Abbreviation,
for waterproofing and to increase its dielectric ORS. A radionavigation station for OMNIRANGE
strength. service.
oil-filled cable A cable whose insulation is impreg- omnigraph A Morse-code generator that operates
nated with oil that can be maintained at a con- via marked or perforated paper tape.
stant pressure. omnirange A radionavigation system in which
oil-filled capacitor See OIL CAPACITOR. each station in a chain broadcasts a beam in all
oil-filled circuit breaker See OIL CIRCUIT directions. It usually operates at very-high fre-
BREAKER. quencies (VHF) or ultra-high frequencies (UHF).
oil-filled transformer A transformer whose case is Pilots of aircraft home on a particular station by
filled with an insulating oil. tuning it in and noting its bearings.
oil fuse cutout A fuse cutout that is filled with an OMR Abbreviation for OPTICAL MARK RECOGNI-
insulating oil. Compare OPEN-FUSE CUTOUT. TION.
oil-immersed transformer See OIL-FILLED TRANS- on air See ON THE AIR.
FORMER. on-call channel An assigned radio channel of
oil-impregnated capacitor See OIL CAPACITOR. which exclusive, full time use is not demanded.
oil pump A vacuum diffusion pump using oil in- on-course curvature In navigation, the rate at
stead of mercury. Also see DIFFUSION PUMP. which the course of a vehicle deviates with refer-
oil switch A switch enveloped by insulating oil. ence to the distance along the true course.
OLRT Abbreviation of online real time (operation). on-course signal A single-tone-modulated signal
OM Amateur radio jargon for OLD MAN: chief indicating to an aircraft pilot following a radio
(male) operator, or husband of female operator. beam that the flight is substantially on course.
omega A phase-dependent radionavigation system on current See ON-STATE CURRENT.
using single-frequency, time-shared, ICW trans- on delay An interval during which a circuit re-
missions from two or more locations. mains off after an actuating signal has been sup-
omnibearing A navigational bearing obtained by plied. Compare OFF DELAY.
means of OMNIRANGE. on-demand system A system, especially in com-
omnibearing converter An electromechanical de- puter and data-processing operations, that deliv-
vice in which an OMNIRANGE signal and vehicle ers information or service immediately upon
heading information are combined, the output request.
being a signal that is fed to a meter. ondograph An electromechanical device that
omnibearing indicator Abbreviation, OBI. An om- graphically draws alternating-current waveforms
nibearing converter with a dial and pointer. on paper.
omnibearing line In an OMNIRANGE system, one ondoscope A radio-frequency (RF) energy detector
of the imaginary lines extending from the geo- that consists of a neon bulb attached to the end
graphic center of the omnirange. of an insulating rod. When a bulb is held in an in-
omnibearing selector A device that can be set tense RF field, the field energy ionizes the gas in
manually to a selected omnibearing. the bulb, causing it to glow without direct con-
omniconstant calculator A calculator that adds nection to the RF circuit.
or multiplies numbers in succession in such a one-address code In computer programming, a
manner as to arithmetically or geometrically in- code in which the address in an instruction refers
crease the exponent as a single button is repeat- to only one memory location.
edly pressed. one condition See ONE STATE.
omnidirectional 1. Pertaining to a device that one-digit adder See HALF ADDER.
responds equally well to acoustic or electro- one-element rotary antenna A directional an-
magnetic energy from any direction in three tenna consisting of a radiator only (no directors
dimensions. 2. Pertaining to a device that radi- or reflectors) that can be rotated. A straight, rigid,
ates acoustic or electromagnetic energy equally half-wave rotatable dipole is the most common
well in any direction in three dimensions. 3. Also, configuration.
NONDIRECTIONAL. Pertaining to an antenna one-for-one compiler A compiler that generates
that intercepts or radiates equally well in any az- one machine language instruction from one
imuth (horizontal) direction. source language instruction.
omnidirectional antenna See NONDIRECTIONAL one-input terminal In a flip-flop, the input termi-
ANTENNA. nal that must be energized to switch the circuit to
omnidirectional hydrophone A hydrophone that its logic 1 output.
picks up underwater sounds coming from any di- one-level address See ABSOLUTE ADDRESS.
rection. one-level subroutine In a computer program, a
omnidirectional microphone A microphone that subroutine in which no reference is made to other
picks up sounds coming from any direction. subroutines.
omnidirectional radio range See OMNIRANGE. one-lunger Colloquialism for a radio transmitter
omnidirectional range See OMNIRANGE. consisting entirely of a one-transistor oscillator.
493
one output • on-state current


one output See ONE STATE. one-way radio See ONE-WAY COMMUNICATION.
one-output signal The signal that results from one-way repeater In wire telephony, a device that
reading a computer memory unit that is in the amplifies and retransmits a signal in the direc-
logic 1 state. tion the signal was traveling when it arrived at
one-output terminal In a flip-flop, the output ter- the repeater. Compare TWO-WAY REPEATER.
minal that is energized when the circuit is in its one-way valve A diode or rectifier (British varia-
logic 1 state. tion).
one-plus-one address A method of computer pro- on interval See ON TIME.
gramming in which instructions contain two ad- online 1. Descriptive of equipment under the con-
dresses and an operation, the addresses referring trol of a central processor. 2. Pertaining to opera-
to the location of the next instruction and the lo- tions being controlled by a central processor.
cation of the data to be used. 3. Relating to a computer storage device indepen-
ones complement Binary notation in the radix- dent of a central processor. 4. In personal com-
minus-one-complement form. puting, the use of a computer in a network (e.g.,
one shot See MONOSTABLE MULTIVIBRATOR. with a modem for operation on the Internet).
one-shot circuit See MONOSTABLE MULTIVI- Compare OFFLINE.
BRATOR. online data reduction Processing data as it enters
one-shot multivibrator See MONOSTABLE MUL- a computer system.
TIVIBRATOR. online editing In video production, the final phase
one-sided wave A waveform consisting of only neg- of editing. The original recording (not copies) is
ative or positive half-cycles. Example: a rectified used to prepare the presentation, based on the
alternating-current signal. trials that were performed using the copies. Com-
one state Also, logic 1 state. The high, on, or true pare OFFLINE EDITING.
logic state of a bistable device, such as a flip-flop. online service A computer network accessible via
Compare ZERO STATE. In binary notation, the telephone lines, television cable systems, and/or
one state is represented by the digit 1. radio. It is generally available to owners of per-
one-third-octave band A frequency band that is 1„3 sonal computers. It provides such services as
octave wide; that is, the difference between electronic mail, special-interest forums, news,
the upper-frequency limit (f2) and the lower- weather, sports, shopping, and general informa-
frequency limit (f1) is one-third of an octave. Also tion.
see OCTAVE BAND. on-off keying Keying, as in radiotelegraphy and
one-to-one assembler An assembler computer wire telegraphy, by switching a signal source on
program that produces a machine language in- and off to form dots and dashes or a binary code,
struction as a result of translating a source- rather than alternately changing the amplitude or
language statement. frequency of the signal.
one-to-one correspondence A mapping between on-off operation A switching operation, especially
two sets A and B so that every element in set A that performed by nonmechanical (fully elec-
has exactly one correspondent in B, and every el- tronic) circuits.
ement in B has exactly one correspondent in A. on-off ratio 1. For a circuit or device, the ratio of
O network A four-impedance network containing off time to on time. 2. For a pulse, the ratio of
two series (upper and lower) arms and two shunt pulse duration to the dead space between pulses.
(input and output) arms. on-off switch 1. In electronic equipment, the
switch by which the equipment can be started or
stopped. It can be, but is not necessarily, the
RS1
power-line or B-plus switch. 2. An electronic cir-
cuit or stage that is designed to operate as a con-
ventional switching element when triggered by an
RSH2 appropriate signal.
Input Output
RSH1
on period See ON TIME.
ONR Abbreviation of Office of Naval Research.
RS2 on resistance See ON-STATE RESISTANCE.
on state 1. For a switch or switching device (such
as a flip-flop), the condition of the device when it
O network conducts current or delivers an output voltage.
Compare OFF STATE, 1. 2. The condition of a cir-
one-way communication 1. The transmission of a cuit or device that is activated for operation.
message to one or more stations that receive only. Compare OFF STATE, 2.
Compare TWO-WAY COMMUNICATION. 2. See on-state current The current flowing through a
BROADCASTING. semiconductor device (such as a diode, rectifier,
one-way conduction See UNILATERAL CONDUC- or thyristor) when it is conducting. Also see ON-
TIVITY. STATE VOLTAGE.
494 on-state resistance • open-frame machine


on-state resistance The resistance of a voltage- open-circuited line See OPEN-CIRCUITED
dependent resistor that is conducting current. TRANSMISSION LINE.
on-state voltage The voltage drop across a semi- open-circuited transmission line Abbreviation,
conductor device (such as a diode, rectifier, or OCTL. An unterminated transmission line in
thyristor) when the device is conducting current. which the conductors at the far end are not con-
Also see ON-STATE CURRENT. nected together.
on the air 1. The state of a radio station that is open-circuit impedance For a transmission line
transmitting. 2. In broadcasting, the condition in or a four-terminal network, the input or driving-
which the transmitter is operational and the point impedance when the output end of the line
sound and/or video from the studio is being dis- or network is open-circuited.
seminated. open-circuit jack A telephone jack that introduces
on time The length of time a switch or switching a break in a circuit until a plug connected to a
device (such as a flip-flop) remains on. closed external circuit is inserted.
on voltage See ON-STATE VOLTAGE. open-circuit plug See OPEN PLUG.
OOP Abbreviation of OBJECT-ORIENTED PRO- open-circuit resistance For a four-terminal net-
GRAMMING. work, the input or driving-point resistance when
op 1. Abbreviation of OPERATE. 2. Abbreviation of the output end of the network is unterminated.
operator (see OPERATOR, 1). 3. Abbreviation of open-circuit signaling A system of signaling in
OPERATION. 4. Abbreviation of operational. which no current flows until the signal circuit is
opacimeter 1. An instrument for measuring the in active operation. In a simple telegraph circuit,
extent to which a material blocks light. 2. An in- for example, current flows only when the key is
strument, such as a field-strength meter, used to pressed (to form a dot or dash).
measure the effectiveness of an electrical shield- open-circuit alarm system A security system in
ing material in blocking radio waves, X rays, or which all the actuating sensors are normally
other radiation. open and connected in parallel. When one of the
opacity The condition of being opaque. This ap- sensors is actuated, it closes, causing a short cir-
plies to all forms of radiation. For example, a cuit that triggers the alarm.
material can be opaque to light rays, but be open-circuit voltage See NO-LOAD VOLTAGE.
transparent to radio waves, or it can be transpar- open-collector configuration In an integrated cir-
ent to gamma rays while being opaque to alpha cuit, an output scheme utilizing no internal pull-
particles. up resistor. Wired-OR outputs can thus have
op amp See OPERATIONAL AMPLIFIER. opposite states without risk of damage to the de-
op code Abbreviation of OPERATION CODE. vice.
open-air line See OPEN-WIRE LINE. open component An open-circuit component (e.g.,
open-back cabinet A loudspeaker enclosure in an open diode, coil, resistor, etc.).
which the space behind the speaker is open to the open core A magnetic core having a cylindrical
room. shape. A disadvantage of this core configuration,
open capacitance The value of a variable capacitor in some applications, is that much of the mag-
whose rotor plates have been rotated completely netic flux extends outside the core. Compare
out of mesh with the stator plates. Compare CLOSED CORE.
CLOSED CAPACITANCE. open-core choke A choke coil wound on an open
open-center display A radar display in which a core. Also called OPEN-CORE INDUCTOR. Com-
ring around the center indicates zero range. pare CLOSED-CORE CHOKE.
open-chassis construction A method of assem- open-core transformer A transformer wound on
bling electronic equipment by mounting compo- an open core. Compare CLOSED-CORE TRANS-
nents and wiring them on an unenclosed chassis, FORMER.
often without a front panel. Similar to breadboard open-delta connection See VEE-CONNECTION
construction. OF TRANSFORMERS.
open circuit 1. A discontinuous circuit (i.e., one open-ended Pertaining to a circuit or device that
that is broken at one or more points and, conse- can be built upon without modifying its original
quently, cannot conduct current nor present a configuration.
voltage at its extremities). Compare CLOSED open-end stub A stub that is neither short-
CIRCUIT. 2. Pertaining to no-load conditions, for circuited nor terminated at its far end.
example, the open-circuit voltage of a battery. open-end stub tuning Adjustment of an OPEN-
3. For a bipolar transistor, the operating character- END STUB, by pruning its length, for optimum
istics under independent input and output condi- operation at a given frequency.
tions. open-entry contact In a connector, an unpro-
open circuit breaker A circuit breaker whose con- tected, opening contact of the female type.
tacts are open. open feeder See OPEN-WIRE LINE.
open-circuit current Current flowing in the pri- open-frame machine See OPEN GENERATOR and
mary winding of an unloaded transformer. OPEN MOTOR.
495
open-fuse cutout • open-wire transmission line


open-fuse cutout A type of enclosed-fuse cutout open-loop voltage gain The overall voltage gain of
having an exposed fuse holder and support. Com- an open-loop amplifier (i.e., one having no feed-
pare OIL FUSE CUTOUT. back). Also see OPEN LOOP.
open generator An unsealed generator (i.e., one open magnetic circuit A magnetic circuit in
that has openings in its housing for air circula- which a complete path is not provided for mag-
tion). netic flux. See, for example, OPEN CORE. Com-
open line 1. See OPEN-WIRE LINE. 2. See OPEN- pare CLOSED MAGNETIC CIRCUIT.
CIRCUITED TRANSMISSION LINE. open motor An unsealed motor (i.e., one that has
open loop 1. In a control system, a feedthrough openings in its housing for air circulation).
path having no feedback and that is not self- open-phase protection Use of an automatic de-
regulating. 2. In an operational amplifier, the vice, such as an open-phase relay, to interrupt
configuration in which there is no feedback, and the power to a polyphase system when one or
in which the device operates at maximum gain. more phases are open-circulated.
3. A loop within a program from which the com- open-phase relay In a polyphase system, a protec-
puter automatically exits after a specific number tive relay that opens when one or more phases
of iterations. are open-circuited. Also see OPEN-PHASE PRO-
TECTION.
open plug A phone plug to which no external con-
+Vcc
nections are made; it is used to hold the blades of
a jack as if they were plugged in.
+ open-reel A tape-recording system in which the
tape, during record or playback condition, is
Input Output wound into a take-up reel that is physically sepa-
’ rate from the tape reel. Also called reel-to-reel
arrangement.
open relay 1. A relay in its open-contact state. 2. A
relay having an open-circuited coil. 3. An unen-
open loop, 2.
closed relay.
open routine In computer operations, a routine
open-loop bandwidth The bandwidth of an open- that can be inserted directly into a larger routine
loop device, such as an amplifier, without feed- and requires no link to the main program.
back. Also see OPEN LOOP. open subroutine In computer operations, a sub-
open-loop control system A control system hav- routine that can be inserted into a larger in-
ing no feedback and that is not self-regulating. structional sequence and must be recopied
An example is a fluid-level gauge that indicates whenever it is required. Also called direct-insert
the height of fluid in a tank, but that cannot cor- subroutine.
rect the level automatically. Compare CLOSED- Open Systems Interconnection Reference Model
LOOP CONTROL SYSTEM. Abbreviation, OSI-RM. A standard set of proto-
open-loop differential voltage gain For a differ- cols for computer network communication. It
ential amplifier, the overall voltage gain (when ei- consists of seven levels, also called layers: physi-
ther input is used) when the amplifier has no cal layer, link layer, network layer, transport
feedback. layer, session layer, presentation layer, and appli-
open-loop gain The overall gain (ratio of output to cation layer.
input) of an open-loop device, such as an ampli- open temperature pickup A temperature trans-
fier without feedback. Also see OPEN LOOP. ducer that must be placed directly in contact with
open-loop input impedance The input impedance the monitored medium.
of an open-loop device, such as an amplifier with- open volume Pertaining to the maximum-gain op-
out feedback. Also see OPEN LOOP. eration of a sound-reproducing system (i.e., oper-
open-loop output impedance The output impe- ation at full volume).
dance of an open-loop device, such as an ampli- open wire 1. An unterminated wire. 2. A wire sup-
fier without feedback. Also see OPEN LOOP. ported above the surface of the earth and often
open-loop output resistance The output resis- ungrounded. 3. See OPEN-WIRE LINE.
tance of an open-loop device, such as an amplifier open-wire feeder See OPEN-WIRE LINE.
without feedback. Also see OPEN LOOP and open-wire line A transmission line or feeder usu-
OPEN-LOOP IMPEDANCE. ally consisting of two straight, parallel wires held
open-loop system 1. A circuit in which the input apart by bars of low-loss insulating material at
and output currents are independent. 2. A robot regular intervals along the line.
that does not use a servo system. It depends en- open-wire loop A branch line connected to a main
tirely on alignment and precision for positioning open-wire line.
accuracy. 3. An electromechanical device that open-wire transmission line See OPEN-WIRE
does not use corrective feedback. LINE.
496 open-wire wavemeter • operating ratio


open-wire wavemeter See LECHER WIRES. operating life The maximum period (from seconds
operand In computer operations, a quantity that to years) over which a device will operate before
enters into or results from an operation. failure (from which it usually cannot recover).
operate 1. To manipulate according to an estab- Compare SHELF LIFE.
lished procedure (e.g., to operate an instrument). operating line A line drawn across a family of
2. To perform according to specifications, in the curves depicting the performance of a device. It
sense that an electronic circuit functions. intersects each curve at a single point and graph-
operate current A signal current or trigger current ically displays the performance of the device for a
required to actuate a device. Compare OPERATE given condition. Thus, an operating line on a fam-
VOLTAGE. ily of output curves for a transistor might depict
operate delay See OPERATE TIME, 1. operation with a given load resistor.
operate interval See OPERATE TIME, 2.
operate time 1. The interval starting after the ap- Operating line:
plication of an operate current or voltage to a de- Ec = 10 V
vice, and ending when the device operates. 2. The
period during which an electronic equipment is in
IB = 200 µA
operation. Also see OPERATING TIME, 1.
operate voltage The signal voltage or trigger volt-




Collector current (Ic)




Y
age required to actuate a device. Compare OPER-
ATE CURRENT. IB = 100 µA




FL
operating ambient temperature Abbreviation,
OAT. The maximum or recommended tempera-
ture in the space immediately surrounding an
equipment in operation.
AM
IB = 50 µA
operating angle In an amplifier circuit, the excita-
tion-signal cycle, in degrees, during which drain,
collector, or plate current flows. Class-A ampli-
fiers operate for 360 degrees of the input signal IB = 20 µA
cycle; class-AB amplifiers operate for more than
TE

180 degrees, but less than 360 degrees of the in-
put signal cycle; class-B amplifiers operate for
Collector voltage (Ec)
180 degrees of the input signal cycle; class-C am-
plifiers operate for less than 180 degrees of the
operating line
input signal cycle.
operating bias In a circuit containing transistors,
diodes, or vacuum tubes, the value(s) of direct- operating overload The extent and/or duration of
current bias required for normal operation. overload to which an equipment can be exposed
operating code The code used by the operator in a during customary operation, and still continue to
computer or data-processing system. properly function.
operating conditions The environment in which a operating point On the response curve for a de-
circuit or system functions in normal use. vice, the point indicating the quiescent level of
operating current The current required by a de- operation (such as determined by a fixed bias
vice during its operation. Compare IDLING CUR- voltage or current). An alternating-current signal
RENT. applied at this point oscillates above and below
operating cycle The sequence of events in the op- the point as a mean.
eration of a device. For example, the repetitive op- operating-point shift A movement of an operating
eration of a neon-bulb relaxation oscillator is a point due to faulty operation of a circuit or device,
sequence of three events: (1) slow charge of ca- or to a value change in some critical component.
pacitor, (2) firing of bulb, and (3) abrupt dis- operating position 1. The control point in a sys-
charge of capacitor. tem, [i.e., the place where an operator (see OPER-
operating frequency 1. The fundamental fre- ATOR, 1) normally functions]. 2. The actual or
quency at which a circuit or device is operated. 2. recommended physical orientation of a device
The frequency of the current, voltage, or power during its operation (e.g., a vertical operating po-
delivered by a generator. sition for a power vacuum tube).
operating frequency range 1. The range of operat- operating power 1. The power actually used by a
ing frequencies, expressed as a minimum and device during its operation. 2. The antenna power
maximum, for a communications receiver, trans- of a radio station.
mitter, or transceiver. 2. For an integrated-circuit operating ratio For a given period, the ratio to/t,
oscillator, the minimum and maximum fre- where to is the time during which an equipment is
quency, and all frequencies in between, at which operating correctly, and t is the duration of the
the device is guaranteed to operate. period.




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