y
`
`IEEE 100
`The Authoritative Dictionary of
`IEEE Standards Terms
`
`Seventh Edition
`
`Published by
`Standards Information Network
`IEEE Press
`
`APPLE 1011
`
`1
`
`

`

`y
`
`Trademarks and disclaimers
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`advanced in this publication.
`
`2
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`

`

`y
`
`beam current
`
`93
`
`bearing
`
`fied surface. Contrast: beam solid angle. See also: footprint.
`(AP/ANT) 145-1993
`beam current (1) (storage tubes) The current emerging from
`the final aperture of the electron gun. See also: storage tube.
`(ED) 158-1962w
`(2) (computer graphics) The flow of electrons from an elec-
`tron gun onto the phosphor-coated screen of a cathode ray
`tube.
`(C) 610.6-1991w
`beam-deflection tube An electron-beam tube in which current
`to an output electrode is controlled by the transverse move-
`ment of an electron beam.
`(ED) 161-1971w
`beam diameter (1) (fiber optics) The distance between two
`diametrically opposed points at which the irradiance is a spec-
`ified fraction of the beam’s peak irradiance; most commonly
`applied to beams that are circular or nearly circular in cross
`section. Synonym: beamwidth. See also: beam divergence.
`(Std100) 812-1984w
`(2) (laser maser) The distance between diametrically op-
`posed points in that cross section of a beam where the power
`per unit area is 1/e times that of the peak power per unit area.
`(LEO) 586-1980w
`beam divergence (laser maser) The full angle of the beam
`spread between diametrically opposed 1/e irradiance points;
`usually measured in mrad (one mrad ⯝ ⌬ 3.4 minutes of arc).
`(LEO) 586-1980w
`(2) (A) (fiber optics) For beams that are circular or nearly
`circular in cross section, the angle subtended by the far-field
`beam diameter. See also: collimation; far-field region; beam
`diameter. (B) (fiber optics) For beams that are not circular or
`nearly circular in cross section, the far-field angle subtended
`by two diametrically opposed points in a plane perpendicular
`to the optical axis, at which points the irradiance is a specified
`fraction of the beam’s peak irradiance. Generally, only the
`maximum and minimum divergences (corresponding to the
`major and minor diameters of the far-field irradiance) need
`be specified. See also: beam diameter; far-field region; col-
`limation.
`(Std100) 812-1984
`beam error (navigation aids) (navigational systems using di-
`rectionally propagated signals) The lateral or angular distance
`between the mean direction of the actual course and the de-
`sired course direction.
`(AES/GCS) 172-1983w
`beam expander (laser maser) A combination of optical ele-
`ments that will increase the diameter of a laser beam.
`(LEO) 586-1980w
`beam finder (oscilloscopes) A provision for locating the spot
`when it is not visible.
`(IM) 311-1970w
`beamguide (laser maser) A set of beam-forming elements
`spaced in such a way as to conduct a well-defined beam of
`radiation. Analogs are waveguides and fiber optic filaments.
`(LEO) 586-1980w
`beam-indexing color tube A color-picture tube in which a sig-
`nal, generated by an electron beam after deflection, is fed back
`to a control device or element in such a way as to provide an
`image in color.
`(ED) 161-1971w
`beam landing error (camera tubes) A signal non-uniformity
`resulting from beam electrons arriving at the target with a
`spatially varying component of velocity parallel to the target.
`See also: camera tube.
`(ED) [45]
`beam locator See: beam finder.
`beam modulation, percentage (image orthicons) One hundred
`times the ratio of the signal output current for highlight illu-
`mination on the tube to the dark current.
`(ED) 161-1971w
`beam noise (navigation aids) (navigational systems using di-
`rectionally propagated signals) Extraneous disturbances tend-
`ing to interfere with ideal system performance. Note: Beam
`noise is the aggregate effect of bends, scalloping, roughness,
`etc.
`(AES/GCS) 172-1983w
`beam parametric amplifier A parametric amplifier that uses a
`modulated electron beam to provide a variable reactance. See
`also: parametric device.
`(ED) [46]
`beam pattern See: directional response pattern.
`
`beam pointing (communication satellite) The ability to orient
`the beam of a high gain antenna into a specific direction in a
`coordinate system.
`(COM) [19]
`beam position See: current position.
`beam power tube An electron-beam tube in which use is made
`of directed electron beams to contribute substantially to its
`power-handling capability, and in which the control grid and
`the screen grid are essentially aligned.
`(ED) 161-1971w
`beam resonator (laser maser) A resonator that serves to con-
`fine a beam of radiation to a given region of space without
`continuous guidance along the beam.
`(LEO) 586-1980w
`beam rider guidance That form of missile guidance wherein a
`missile, through a self-contained mechanism, automatically
`guides itself along a beam. See also: guided missile.
`(EEC/PE) [119]
`beamshape loss A loss factor included in the radar equation to
`account for the use of the peak antenna gain in the radar
`equation instead of the effective gain that results when the
`received train of pulses is modulated by the two-way pattern
`of a scanning antenna. Synonym: antenna-pattern loss.
`(AES) 686-1997
`beam shaping (communication satellite) Controlling the shape
`of an antenna beam, by design of the surfaces of the antenna
`or by controlling the phasing of the signals radiated from the
`antenna.
`(COM) [25]
`beam solid angle The solid angle through which all the radiated
`power would stream if the power per unit solid angle were
`constant throughout this solid angle and at the maximum
`value of the radiation intensity.
`(AP/ANT) 145-1993
`beamsplitter (fiber optics) A device for dividing an optical
`beam into two or more separate beams; often a partially re-
`flecting mirror.
`(Std100) 812-1984w
`beam splitter (laser maser) An optical device which uses con-
`trolled reflection to produce two beams from a single incident
`beam.
`(LEO) 586-1980w
`beam spot size See: spot size.
`beam spread (1) (illuminating engineering) (in any plane) The
`angle between the two directions in the plane in which the
`intensity is equal to a stated percentage of the maximum beam
`intensity. The percentage typically is 10% for floodlights and
`50% for photographic lights.
`(EEC/IE) [126]
`(2) (light-emitting diodes) (source of light, ␪ y, where y is
`the stated percent.) See definition (1) above.
`(ED) [127]
`beam steering (1) Changing the direction of the major lobe of
`a radiation pattern. See also: radiation.
`(AP/ANT) [35], 145-1993
`(2) Surface acoustic wave propagation phenomena in aniso-
`tropic materials described by a nonzero angle of power flow.
`(UFFC) 1037-1992w
`beam waveguide A quasioptical structure consisting of a se-
`quence of lenses or mirrors used to guide an electromagnetic
`wave.
`(MTT) 146-1980w
`beamwidth See: beam diameter; half-power beamwidth.
`bearer channel protocol intervention level The highest pro-
`tocol level at which a private switching network (PSN) pro-
`vides protocol termination on a given bearer channel.
`(LM/C/COM) 8802-9-1996
`bearer service A telecommunication service that provides the
`capability for the transmission of signals between user-net-
`work interfaces.
`
`(C/LM/COM) 802.9a-1995w, 8802-9-1996
`bearing (A) (navigation aid terms) The horizontal direction of
`one terrestrial point from another, expressed as the angle in
`the horizontal plane between a reference line and the hori-
`zontal
`projection
`of
`the
`line
`joining
`two
`points.
`(B) (navigation aid terms) Azimuth. A bearing is often des-
`ignated as true, magnetic, compass, grid, or relative, and is
`dependent upon the reference direction.
`(AES/GCS) 172-1983
`(2) (A) (rotating machinery) A stationary member or as-
`sembly of stationary members in which a shaft is supported
`and may rotate. (B) (rotating machinery) In a ball or roller
`
`3
`
`

`

`y
`
`bearing accuracy, instrumental
`
`94
`
`becquerel
`
`bearing, a combination (frequently preassembled) of station-
`ary and rotating members containing a peripheral assembly
`of balls or rollers, in which a shaft is supported and may
`rotate.
`(PE) [9]
`bearing accuracy, instrumental (A) (direction finding sys-
`tems) The difference between the indicated and the apparent
`bearings in a measurement of the same signal source. See
`also: navigation. (B) (direction finding systems) As a state-
`ment of overall system performance, a difference between
`indicated and correct bearings whose probability of being ex-
`ceeded in any measurement made on the system is less than
`some stated value. See also: navigation.
`(AES) [42]
`bearing bracket (rotating machinery) A bracket which sup-
`ports a bearing, but including no part thereof. A bearing
`bracket is not specifically constructed to provide protection
`for the windings or rotating parts.
`(PE) [9]
`bearing cap (rotating machinery) (or bearing bracket cap) A
`cover for the bearing enclosure of a bearing bracket type ma-
`chine or the removable upper half of the enclosure for a bear-
`ing. See also: bearing.
`(PE) [9]
`bearing cartridge (rotating machinery) A complete enclosure
`for a ball or roller bearing, separate from the bearing bracket
`or end shield. See also: bearing.
`(PE) [9]
`bearing clearance (A) (rotating machinery) The difference
`between the bearing inner diameter and the journal diameter.
`See also: bearing. (B) (rotating machinery) The total dis-
`tance for axial movement permitted by a double-acting thrust
`bearing. See also: bearing.
`(PE) [9]
`bearing distance heading indicator (navigation aid terms) A
`display device which presents continuous references as to
`course and distance to destination.
`
`(AES/GCS) 172-1983w
`bearing dust-cap (rotating machinery) A removable cover to
`prevent the entry of foreign material into the bearing. See
`also: bearing.
`(PE) [9]
`bearing error curve (A) (navigation aid terms) [DF (direction
`finder) equipment]. A plot of the instrumental bearing errors
`versus either indicated or correct bearing. (B) (navigation aid
`terms) (in DF installations) A plot of the combined instru-
`mental bearing error (of the equipment) and site error versus
`indicated bearings.
`(AES/GCS) 172-1983
`bearing housing (rotating machinery) A structure supporting
`the actual bearing liner or ball or roller bearing in a bearing
`assembly. See also: bearing.
`(PE) [9]
`bearing insulation (rotating machinery) Insulation that pre-
`vents the circulation of stray currents by electrically insulat-
`ing the bearing from its support. See also: bearing.
`
`(PE) [9]
`bearing liner (rotating machinery) The assembly of a bearing
`shell together with its lining. See also: bearing.
`(PE) [9]
`bearing lining (rotating machinery) The element of the journal
`bearing assembly in which the journal rotates. See also: bear-
`ing.
`(PE) [9]
`bearing locknut (rotating machinery) A nut that holds a ball
`or roller bearing in place on the shaft. See also: bearing.
`(PE) [9]
`bearing lock washer (rotating machinery) A washer between
`the bearing locknut and the bearing that prevents the locknut
`from turning. See also: bearing.
`(PE) [9]
`bearing offset, indicated (electronic navigation) (direction
`finding systems) The mean difference between the indicated
`and apparent bearings of a number of signal sources, the
`sources being substantially uniformly distributed in azimuth.
`See also: navigation.
`(AES/GCS) 173-1959w, [42]
`bearing oil seal See: oil seal.
`bearing oil system (rotating machinery) (oil-circulating sys-
`tem) All parts that are provided for the flow, treatment, and
`storage of the bearing oil. See also: oil cup.
`(PE) [9]
`bearing pedestal (rotating machinery) A structure mounted
`from the bedplate or foundation of the machine to support a
`bearing, but not including the bearing. See also: bearing.
`(PE) [9]
`
`bearing-pedestal cap (rotating machinery) The top part of a
`bearing pedestal. See also: bearing.
`(PE) [9]
`bearing plates Plates of large surface area attached to the struc-
`ture below ground surface to prevent uplift or to increase the
`bearing capability in unstable soils.
`(T&D/PE) 751-1990
`bearing protective device (power system device function num-
`bers) A device that functions on excessive bearing tempera-
`ture, or on other abnormal mechanical conditions associated
`with the bearing, such as undue wear, which may eventually
`result in excessive bearing temperature or failure.
`(SUB/PE) C37.2-1979s
`bearing reciprocal See: reciprocal bearing.
`bearing reservoir (rotating machinery) (oil tank) (oil well) A
`container for the oil supply for the bearing. It may be a sump
`within the bearing housing. See also: oil cup.
`(PE) [9]
`bearing seal See: oil seal.
`bearing seat (rotating machinery) The surface of the support-
`ing structure for the bearing shell. See also: bearing.
`(PE) [9]
`bearing sensitivity (electronic navigation) The minimum field
`strength input to a direction-finder system to obtain repeatable
`bearings within the bearing accuracy of the system. See also:
`navigation.
`(AES) 270-1966w, [42]
`bearing shell (rotating machinery) The element of the journal
`bearing assembly that supports the bearing lining. See also:
`bearing.
`(PE) [9]
`bearing shoe See: segment shoe.
`bearing-temperature detector (rotating machinery) A tem-
`perature detector whose sensing element is mounted at or near
`the bearing surface. See also: bearing.
`(PE) [9]
`bearing-temperature relay (rotating machinery) A relay
`whose temperature sensing element is mounted at or near the
`bearing surface. Synonym: bearing thermostat. See also: bear-
`ing.
`(PE) [9]
`bearing thermometer (rotating machinery) A thermometer
`whose temperature sensing element is mounted at or near the
`bearing surface. See also: bearing.
`(PE) [9]
`bearing thermostat See: bearing-temperature relay.
`beat An event that begins with the transition on a synchroni-
`zation line by the master, followed by the release of an ac-
`knowledge line by one or more slaves. Command and data
`information may be transferred from the master to one or
`more slaves in the first half of the beat. During the second
`half of the beat the slaves may transfer capability, status, and
`data information back to the master.
`(C/BA) 10857-1994, 896.4-1993w, 896.3-1993w
`beating (data transmission) A phenomenon in which two or
`more periodic quantities of different frequencies produce a
`resultant having pulsations of amplitude.
`(PE) 599-1985w
`beat note The wave of difference frequency created when two
`sinusoidal waves of different frequencies are supplied to a
`nonlinear device. See also: radio receiver.
`188-1952w
`beat reception See: heterodyne reception.
`beats (1) (general) Periodic variations that result from the su-
`perposition of waves having different frequencies. Note: The
`term is applied both to the linear addition of two waves, re-
`sulting in a periodic variation of amplitude, and to the non-
`linear addition of two waves, resulting in new frequencies, of
`which the most important usually are the sum and difference
`of the original frequencies. See also: signal wave.
`(COM) 312-1977w
`(2) (data transmission) Periodic variations that result from
`the superposition of waves having difference frequencies.
`Note: The term is applied both to the linear addition of two
`waves, resulting in a periodic variation of amplitude, and to
`the nonlinear addition of two waves, resulting in new fre-
`quencies, of which the most important usually are the sum
`and difference of the original frequencies.
`(PE/EDPG) 599-1985w, [3]
`becquerel (metric practice) The activity of a radionuclide de-
`caying at the rate of one spontaneous nuclear transition per
`second.
`(QUL) 268-1982s
`
`4
`
`

`

`y
`
`direct ESD event
`
`315
`
`directional-hemispherical reflectance
`
`directional control (as applied to a protective relay or relay
`scheme) A qualifying term that indicates a means of control-
`ling the operating force in a nondirectional relay so that it will
`not operate until the two or more phasor quantities used to
`actuate the controlling means (directional relay) are in a pre-
`determined band of phase relations with a reference input.
`(SWG/PE) C37.100-1992
`directional coupler (1) (A) (transmission lines) A transmis-
`sion coupling device for separately (ideally) sampling
`(through a known coupling loss for measuring purposes) ei-
`ther the forward (incident) or the backward (reflected) wave
`in a transmission line. Notes: 1. Similarly, it may be used to
`excite in the transmission line either a forward or backward
`wave. 2. A unidirectional coupler has available terminals or
`connections for sampling only one direction of transmission;
`a bidirectional coupler has available terminals for sampling
`both directions. See also: auxiliary device to an instrument.
`(B) (tap) A passive device used in cable systems to divide
`and combine RF signals. It has at least three ports: line in,
`line out, and the tap. The signal passes between line in and
`line out ports with loss referred to as the insertion loss. A
`small portion of the signal power applied to the line in port
`passes to the tap port. A signal applied to the tap port is passed
`to the line in port less the tap attenuation value. The tap sig-
`nals are isolated from the line out port to prevent reflections.
`A signal applied to the line out port passes to the line in port
`and is isolated from the tap port. Some devices provide more
`than one tap output line (multi-taps).
`(LM/EEC/PE/C) [119], 802.7-1989
`(2) (waveguide components) A four port junction consisting
`of two waveguides coupled together in such a manner that a
`single traveling wave in either guide will induce a single trav-
`eling wave in the other, the direction of the latter wave being
`determined by the direction of the former.
`(MTT) 147-1979w
`
`(3) (fiber optics) See also: tee coupler.
`directional-current tripping See: directional-overcurrent pro-
`tection; directional-overcurrent relay.
`directional gain directivity index (transducer) (audio and
`electroacoustics) In decibels, 10 times the logarithm to the
`base 10 of the directivity factor.
`(SP) [32]
`directional-ground relay A directional relay used primarily to
`detect single-phase-to-ground faults, but also sensitive to dou-
`ble-phase-to-ground faults. Note: This type of relay is usually
`operated from the zero-sequence components of voltage and
`current, but is sometimes operated from negative-sequence
`quantities.
`(SWG/PE/PSR) C37.100-1992, C37.90-1978s
`directional gyro A two-degree-of-freedom gyro with a provi-
`sion for maintaining the spin axis approximately horizontal.
`In this gyro, an output signal is produced by gimbal angular
`displacement that corresponds to the angular displacement of
`the case about an axis that is nominally vertical.
`(AES/GYAC) 528-1994
`directional gyro electric indicator An electrically driven de-
`vice for use in aircraft for measuring deviation from a fixed
`heading.
`(EEC/PE) [119]
`directional-hemispherical reflectance [␳(␪i, ␾i2␲)] Ratio of
`reflected flux collected over the entire hemisphere to essen-
`tially collimated incident flux. (See figure below). Note: The
`direction of incidence must be specified.
`
`␲2
`
`i␾
`
`i␪
`
`Hemispherical
`Directional
`Collected
`Incident
`directional-hemispherical reflectance
`(EEC/IE) [126]
`
`direct ESD event An ESD event that takes place between an
`intruder and a receptor in which the intruder or the receptor,
`or both, is an equipment victim.
`(SPD/PE) C62.47-1992r
`direct ESD test A test in which ESD is applied directly to the
`surface or structure of the EUT.
`(EMC) C63.16-1993
`direct feeder A feeder that connects a generating station, sub-
`station, or other supply point to one point of utilization. See
`also: center of distribution; auxiliary device to an instrument;
`radial feeder.
`(EEC/PE) [119]
`direct glare (illuminating engineering) Glare resulting from
`high luminances or insufficiently shielded light sources in the
`field of view. It usually is associated with bright areas, such
`as luminaires, ceilings, and windows which are outside the
`visual task or region being viewed.
`(EEC/IE) [126]
`direct grid bias The direct component of grid voltage. See also:
`electrode voltage.
`(ED) 161-1971w
`direct-indirect lighting (illuminating engineering) A variant
`of general diffuse lighting in which the luminaires emit little
`or no light at angles near the horizontal.
`(EEC/IE) [126]
`direct insert subroutine See: open subroutine.
`direct instruction (1) A computer instruction that contains the
`direct addresses of its operands. Contrast: immediate instruc-
`tion; indirect instruction. See also: absolute instruction; ef-
`fective instruction.
`(C) 610.12-1990
`(2) A computer instruction that contains the direct addresses
`of its operands. Contrast: indirect instruction.
`(C) 610.10-1994w
`direct interelectrode capacitance (electron tube) The direct
`capacitance between any two electrodes excluding all capac-
`itance between either electrode and any other electrode or
`adjacent body.
`(Std100) [84]
`direct inward dialing (telephone switching systems) A private
`automatic branch exchange or centrex service feature that per-
`mits outside calls to be dialed directly to the stations.
`(COM) 312-1977w
`direct I/O An operation that attempts to circumvent a system
`performance optimization for the optimization of the individ-
`ual I/O operation.
`(C/PA) 9945-1-1996
`direction (navigation aid terms) The position of one point in
`space relative to another without reference to the distance
`between them; direction may be either three dimensional or
`two dimensional, and it is not an angle, but is often indicated
`in terms of its angular difference from a reference direction.
`Note: Five terms used in navigation— azimuth, bearing,
`course, heading, and track— involve measurement of angles
`from reference directions. To specify the reference directions,
`certain modifiers are used. These are: true, magnetic, com-
`pass, relative, grid and gyro.
`(AES/GCS) 172-1983w
`directional antenna An antenna having the property of radiat-
`ing or receiving electromagnetic waves more effectively in
`some directions than others. Note: This term is usually ap-
`plied to an antenna whose maximum directivity is signifi-
`cantly greater than that of a half-wave dipole.
`(AP/ANT) 145-1993
`directional-comparison protection A form of pilot protection
`in which the relative operating conditions of the directional
`units at the line terminals are compared to determine whether
`a fault is in the protected line section.
`(SWG/PE/PSR) C37.100-1992, C37.90-1978s
`directional conical reflectance Ratio of reflected flux collected
`through a conical solid angle to essentially collimated inci-
`dent flux. Note: The direction of incidence must be specified,
`and the direction and extent of the cone must be specified.
`(EEC/IE) [126]
`directional conical transmittance Ratio of transmitted flux col-
`lected through a conical solid angle to essentially collimated
`incident flux. Note: The direction of incidence must be spec-
`ified, and the direction and extent of the cone must be spec-
`ified.
`(EEC/IE) [126]
`directional constraint A technique used in computer graphics
`to force an input line to be parallel with a particular two-
`dimensional or three-dimensional axis.
`(C) 610.6-1991w
`
`5
`
`

`

`y
`
`transaction initiation
`
`1198
`
`transducer loss
`
`plicitly in a transaction-initiation message and returned in a
`transaction-completion message.
`(C/MM) 1212.1-1993
`transaction initiation (request) A request generated by the in-
`itiator to start an action by the responder. An initiation mes-
`sage usually transfers a command and sometimes data. For a
`disk read I/O transaction, for example, the initiation transfers
`the address and command.
`(C/MM) 1212.1-1993
`transaction, I/O See: I/O transaction.
`transaction layer (1) The layer above the packet layer for use
`by applications. It is unspecified in this standard. See also:
`transaction.
`(C/BA) 1355-1995
`(2) The layer, in a stack of three protocol layers defined for
`the Serial Bus, that defines a request-response protocol to
`perform bus operations of type read, write, and lock.
`(C/MM) 1394-1995
`transaction matrix A matrix that identifies possible requests
`for database access and relates each request to information
`categories or elements in the database.
`(C) 610.12-1990
`transaction record A record, representing one transaction, used
`to process data stored in a master file. See also: update trans-
`action; null transaction; change transaction; delete transac-
`tion; add transaction.
`(C) 610.2-1987
`transactor A magnetic device with an air-gapped core having
`an input winding which is energized with an alternating cur-
`rent and having an output winding which produces a voltage
`that is a function of the input current. Note: The term “trans-
`actor” is a contraction of the words “transformer” and
`“reactor.”
`(SWG/PE/PSR) C37.110-1996, C37.100-1992
`transadmittance For harmonically varying quantities at a given
`frequency, the ratio of the complex amplitude of the current
`at one pair of terminals of a network to the complex amplitude
`of the voltage across a different pair of terminals. See also:
`interelectrode transadmittance.
`(IM/HFIM) [40]
`transadmittance compression ratio (electron tube) The ratio
`of the magnitude of the small-signal forward transadmittance
`of the tube to the magnitude of the forward transadmittance
`at a given input signal level.
`(ED) 161-1971w
`transadmittance, forward See: forward transadmittance.
`transceiver (1) (data transmission) The combination of radio
`transmitting and receiving equipment in a common housing,
`usually for portable or mobile use, and employing common
`circuit components for both transmitting and receiving.
`(PE) 599-1985w
`(2) (navigation aids) A combination transmitter and receiver
`in a single housing, with some components being used by
`both parts. See also: transponder.
`(AES/GCS) 172-1983w
`(3) (A) A device that both transmits and receives data. (B) A
`device that connects a host interface to a network. (C) A
`device that applies electronic signals to the cable and may
`sense collisions. Note: Definition (C) is contextually specific
`to IEEE Std 802.3.
`(C) 610.7-1995
`transceiver cable A four-pair, shielded cable which intercon-
`nects a workstation to a transceiver or fan-out box. Note: This
`term is contextually specific to IEEE Std 802.3. See also:
`coaxial cable; trunk cable; drop cable; attachment unit inter-
`face cable.
`(C) 610.7-1995
`transceiver chatter See: chatter.
`transconductance The real part of the transadmittance. Note:
`Transconductance is, as most commonly used, the interelec-
`trode transconductance between the control grid and the plate.
`At low frequencies, transconductance is the slope of the con-
`trol-grid-to-plate transfer characteristic. See also: interelec-
`trode transconductance; electron-tube admittances.
`(ED) 161-1971w
`transconductance meter (mutual-conductance meter) An in-
`strument for indicating the transconductance of a grid-con-
`trolled electron tube. See also: instrument.
`
`(EEC/PE) [119]
`transcribe (electronic computation) To convert data recorded
`in a given medium to the medium used by a digital computing
`machine or vice versa.
`(C) 162-1963w
`
`transcriber (electronic computation) Equipment associated
`with a computing machine for the purpose of transferring in-
`put (or output) data from a record of information in a given
`language to the medium and the language used by a digital
`computing machine (or from a computing machine to a record
`of information).
`(Std100) 270-1966w
`transducer (1) (electrical heating applications to melting fur-
`naces and forehearths in the glass industry) A device that is
`actuated by power from one system and supplies power in
`any other form to a second system.
`(IA) 668-1987w
`(2) (communication and power transmission) A device by
`means of which energy can flow from one or more transmis-
`sion systems or media to one or more other transmission sys-
`tems or media. Note: The energy transmitted by these systems
`or media may be of any form (for example, it may be electric,
`mechanical, or acoustical), and it may be of the same form
`or different forms in the various input and output systems or
`media.
`(MIL/C/AP/ANT) [2], [85], 145-1983s
`(3) (metering) A device to receive energy from one system
`and supply energy (of either the same or of a difference kind)
`to another system, in such a manner that the desired charac-
`teristics of the energy input appear at the output.
`(ELM) C12.1-1988
`(4) (thyristor) A device which under the influence of a
`change in energy level of one form or in one system, produces
`a specified change in energy level of another form or in an-
`other system.
`(IA/IPC) 428-1981w
`(5) A device for converting energy from one form to another.
`(C) 610.10-1994w
`(6) A device converting energy from one domain into another.
`The device may either be a sensor or an actuator.
`(IM/ST) 1451.2-1997
`(7) A device converting energy from one domain into another,
`calibrated to minimize the errors in the conversion process.
`A sensor or an actuator.
`(IM/ST) 1451.1-1999
`transducer, active See: active transducer.
`Transducer Block An instance of a subclass of IEEE1451㛮
`TransducerBlock.
`(IM/ST) 1451.1-1999
`transducer conversion loss The ratio of the SAW power gen-
`erated in the substrate at the transducer output to the power
`available in the circuit at the transducer input in decibels.
`(UFFC) 1037-1992w
`Transducer Electronic Data Sheet (TEDS) (1) A data sheet
`describing a transducer stored in some form of electronically
`readable memory.
`(IM/ST) 1451.2-1997
`(2) Several of the IEEE 1451.X standards use TEDS to pro-
`vide a machine-readable specification of the characteristics of
`the transducer interface.
`(IM/ST) 1451.1-1999
`transducer gain (1) The ratio of the power that the transducer
`delivers to the specified load under specified operating con-
`ditions to the available power of the specified source. Notes:
`1. If the input and/or output power consist of more than one
`component, such as multifrequency signals or noise, then the
`particular components used and their weighting must be spec-
`ified. 2. This gain is usually expressed in decibels. See also:
`transducer.
`(Std100) 270-1966w
`(2) (two-port linear transducer) At a specified frequency,
`the ratio of the actual signal power transferred from the output
`port of the transducer to its load, to the available signal power
`from the source driving the transducer.
`(ED) 161-1971w
`transducer, ideal See: ideal transducer.
`Transducer Independent Interface The digital interface used
`to connect a Smart Transducer Interface Module to a Network
`Capable Application Processor.
`(IM/ST) 1451.2-1997
`transducer interface The physical connection by which a trans-
`ducer communicates with the control or data systems that it
`is a member of, including the physical connector, the signal
`wires used and the rules by which information is passed
`across the connection.
`(IM/ST) 1451.2-1997
`transducer, line See: line transducer.
`transducer loss The ratio of the available power of the specified
`source to the power that the transducer delivers to the speci-
`
`6
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