Glossary of Terms




A
Absolute Pressures (PSIA)
Sealed sensor unit which measures pressure relative to an internally sealed vacuum. Typically applications are P0, P3 in aircraft engine applications. Also sometimes used for high pressure such as hydraulic, brake and oxygen pressures.
Acceleration Sensitivity (Error)
The maximum difference at any measurand value between the output with and without the application of a specified constant acceleration along specified axes. Normally specificied in transverse and perpendicular directions. (% FSO/g)
Accuracy
The ratio of error to Full Scale Output often expressed in percent of Full Scale output. (%FSO)
Acceptor
A material added as a dopant to a semiconductor to make it p-type by accept-in valence electrons and leaving holes behind that can conduct electric charges. Normally Boron is used for doping Silicon.
A/D
Abbreviation for analog to ditigal
A/D converter
An electronic device used to convert an analog voltage to a digital signal.
Altitude
The verticle distance above a specified reference datum such as sea level.
Ambient Conditions
The conditions (Pressure, temperature, etc.) of the device's environment.
Analog Output
An output of analog voltage derived from processing of digital and/or analog input to circuitury within an (electronic) device. Normally a continuous function of the measurand except as modified by device resolution.
Angstrom
A unit for Ultra-high frequencies equal to ten raised to the power -10 meters.
Annealing
A heating process that reverse damage to the crystal structure or to activate dopant.
Attitude Error
The error due to the orientation of the device relative to direction of the force of gravity on the transducer.

B
Bandwidth
The highest frequency signal component that can pass through input amplifiers without being attenuated.
Best Fit Straight Line
A line midway between two parallel straight lines closest together and enclosing all output points of the instrumentation between zero load and full scale.
Breakdown Voltage Rating
The voltage (AC or DC) which can be applied across the transducer insulation without causing arcing or conduction above a specified current.
Bridge Resistance
Resistance of transducer bridge elements ( input or output impedance).
Burst Pressure Rating
The pressure which may be applied to the sensing element or the transducer case just prior to rupture of either. A minimum number of applications and time duration are also often specified.

C
Calibration
A test to determine the output signal of the device with a steady input excitation and known values of the parameter under controlled conditions
Calibration Curve
A graphical representation of the device output vs. measurand under controlled conditions.
Calibration Cycle
The application of controlled values of a parameter proving an output signal over the full range of the instrument in ascending and descending order.
Combined and Hysteresis
Square of the sums of squares of error due to non-linearity and that of and Hysteresis non-linearity.

Compensated Temperature Range
Range of temperatures over which the transducer has been corrected by the addition of a circuit to correct the output for errors induced by the change in bridge resistance due to temperature.
Compensation
Addition of supplemental device, circuit, or special materials to reverse known source of errors.

D
D/A
Abbreviation for Digital to Analog.
D/A Converter
A device for converting a digital signal to an analog signal.
Damping
An energy absorbing factor that in conjunction with the natural frequency determines the limit of frequency response and the response time characteristics of a transducer. In response to a step function of the parameter a periodic (underdamped) system oscillates about the voltage level before stabilizing at its final steady output; an aperiodic (overdamped) system comes to the final steady output without overshooting; and a critically damped system is defined as one that is at the point of changing from a periodic to a aperiodic system.
Dead Volume
Total volume of the pressure port cavity of a transducer with room barometric pressure applied.
Decibel
A unit of logarithmic measure based on the ratio of power related quantities such as sound, volts, or watts to a specified reference in same units.
Deposition
The procedure of deposit materials onto a substrate by means of vacuum, electrical, screening, or vapor techniques.
Dice, Die
A section of a processed wafer, usually rectangular, which contains one functional circuit.
Dielectric
An insulating layer. A material that has high resistance.
Dielectric Strength
Same as breakdown voltage.
Differential Pressures (PSID)
The transducer measures the difference between two pressure sources connected to two inlet ports. Differential transducers are used in pressure applications such as across filters.
Diffusion
A process used in semiconductor production by adding small amounts of impurities or dopants to a semiconductor.
Digital Output
Transducer output that represents the magnitude of the parameter measured in terms of discrete quantities or codes in a system of notation. 0 and 1 are commonly used. Digital and analog are common output types.
Donor
A material added as a dopant to a semiconductor to make it n-type by donating valence electrons which can conduct electric charge. An example is phosphorus.
Dopant
A material added in minute quantities to a semiconductor to alter it's electrical conducting characteristics. They may be donors or acceptors.
Doping
The process of adding a dopant to semiconductor material.
Drift
A undesired change of a reading with no charge in the input signal or operating conditions.
Dynamic Characteristics
The characteristics of a transducer which describes its response to variations in measurand pressure over time.

E
Electrical Connection
The portion of the transducer assembly used to connect, disconnect, and reconnect the electrical wiring that carries excitation voltage, signal or current to and from the transducer.
Environmental Conditions
Specific external conditions, such as shock, vibration, temperature, moisture, etc. to which a transducer may be exposed during normal operations.
End Point
Output signal at upper and lower limits of the transducer range.
End Point Line
Line drawn between the end points of a transducer calibration.
Environmental Conditions
Specified external conditions ,such as shock, vibration, temperature, moisture, etc. to which a transducer may be exposed during normal operations.
Environmental Conditions, Operating
Specified external conditions ,such as shock, vibration, temperature, moisture, etc. when a transducer is exposed to must perform as specified.
Error
The mathematical difference between the indicated value and the true value of the parameter signal.
Error Band
The band of maximum deviations of output values from a specified reference line or curve due to those causes attributable to the transducer. Usually described as plus or minus some value of transducer full scale output.
Excitation
The external electrical voltage and/or current applied to a sensor assembly to initiate the proportional output. Usually expressed in ranges the transducer may subjected to without damage. The value of this voltage is set by calibration and any serious deviation from this value will negate the calibration.
Extrinsic Semiconductor
A semiconductor that has been doped either n-type or p-type. Electrons and holes are present in unequal proportions (by 4 to 8 orders of magnitude).

F
Frequency Modulated Output
An output in the form of frequency deviations from a center frequency, where the deviation is a function of the measured parameter.

Frequency Output
An output in the form of frequency which varies as a function of the applied measurand.
Frequency, Natural
The frequency of free (not forced) oscillations of the sensing element of a fully assembled transducer.
Frequency, Resonant
The input frequency at which a transducer responds with maximum output amplitude. If there is more than one frequency the lowest is the resonant frequency
Frequency Response
The change with frequency of the output/parameter amplitude ratio( and of the phase difference between the output and the parameter) for sinusoidal varying measurand applied to a transducer within a specified range. It is normal consider at plus or minus 3 db and is given by the approximation. F.R.= 1/2pt Freq. Response= 1 divided by 2 times Pi times time constant
Full Scale Output
The value of transducer output at the maximum rated load minus the output at the minimum rated load.

G
Gage Factor
A measure of the ratio of the relative change of resistance to the relative change in length of a resistance strain transducer (strain gage).
Gage Pressures (PSIG)
The pressure is measured relative to ambient pressure such as oil pressure. Kulite uses a patented dual diaphragm (dual sensor) approach consisting of a first sensor to measure the primary pressure and a secondary sensor to measure the ambient pressure. The outputs are subtracted to give a true gage pressure reading. This approach yields a hermetically sealed vented gage pressure transducer. Typical applications are engine oil, gear box oil and fuel pressures.

H
Hysteresis
The maximum difference in output, at any measurand value within the specified range, when the value is approached first with increasing and then decreasing measurand. Normally expressed in % FSO.

I
IEEE
Abbreviation for Institute of Electrical and Electronics Engineers.
Input
Measurand signal (and/or exciting voltage or current).
Input Impedance
The impedance (presented to the excitation source) measured across the excitation terminals of the transducer. Unless otherwise specified the impedance is measured at room temperature, etc.
Insulation Resistance
The resistance measured between specified insulated portions of a transducer when a specified DC voltage is applied at ambient conditions- room temperature etc.
Ion
The result of an atom losing an electron and becoming positive or gaining an electron and becoming negative.

J, K, L
Leakage Rate
The maximum rate at which a fluid is observed or permitted to leak through a seal. The type of fluid, differential pressure across the seal, and the direction of flow should be specified. Units are normally Volume or pressure drop per unit of time.
Least Squares Line
The straight line for which the sum of the squares of the residuals (deviations) is minimized.
Life, Cycle
The specified number of full and/or partial range excursions over which a device will operate within specified performance criteria.
Life, Operating
The length of time over which device will operate to a specified performance.
Life, Storage
The length of time over which device can be stored at specified conditions and still operate to a specified performance.
Linearity
The closeness of a calibration curve to a specified straight line expressed as % FSO.
Load Impedance
The impedance presented to the output terminals of the transducer by the external circuitry connected to the device.

M
Maximum Ambient Temperature
The value of the highest (and the lowest) ambient temperatures that a (Minimum) transducer can be exposed to with or without excitation applied, without being damaged and subsequently suffering performance degradation.
Maximum Excitation
Value of excitation voltage or current that can be applied to the transducer at room conditions without causing damage or performance degradation.
Measurand (Parameter)
A physical quantity, property, or condition, which is measured, Sometimes called input, parameter, or variable.
Measured Fluid
The fluid that comes in contact with the sensing element. Chemical and/or physical properties of this fluid may be specified to insure proper transducer operation and life.
Mounting Error
An error due to mechanical deformation of the transducer caused by mounting the device and/or making the electrical connection.

N
Natural Frequency
See Frequency, Natural
Non-Linearity
See Linearity. Normally expressed as % FSO.
Non-Operating Conditions
Any conditions outside of operating conditions that might cause transducer to malfunction.

Non-Repeatability
Breakdown of the transducer characteristics of repeatability a small amount of which is contained in an acceptable error band. Usually expressed as % FSO.
Null
A condition, such as of balance, which results in a minimum absolute value of output.

O
Operation Mode
A description of how the transducer is used to provide a usable signal representating a measurand variation.
Operating Conditions
See environmental conditions.
Operating Temperature Range
Temperature range the operating transducer will be subjected to.

Output
The electrical quantity produced by the transducer which is a function of the applied measurand.
Output Impedance
The impedance across the output terminals of a transducer presented by the transducer to the associated external circuitry.
Output Noise
The RMS or peak to peak, as specified, ac component of a transducer's DC >output in the absence of measurand variations.
Output Range
Design band of output for specified input.
Overload
The maximum value of a measurand that can be applied to a transducer without damage or change in performance beyond a specified tolerance.
Over Pressure
See Overload.

P
Pressure Range
Lowest to the highest pressures to be measured by a specific transducer.
Pressure Media
See measured fluid.

Q, R
Range
The measurand values over which a transducer is designed to measure. Indicated by upper and lower values.
Rated Electrical Excitation
The electrical voltage supply the transducer sensing element for normal operation given the specified output with the application of a known measurand.
Reference Pressure
The pressure applied to the opposite side of the sensing element- ambient pressure for gage and perfect vacuum for absolute designs.
Reference Pressure Error
The error in transducer output resulting from errors in the reference pressure value within a specified reference pressure range.

Reference Pressure Range
The range of pressures that can be applied to the backside of a sensing element without changing the pressure transducer's performance beyond specified tolerances. If no tolerance is specified, none is allowed.
Reference Pressure Sensitivity Shift
The sensitivity shift resulting from variations of a differential pressure transducer's reference pressure within specified limits.

Repeatability
The ability of a transducer to reproduce output values when the same measurand value is applied repeatedly under the same conditions and in the same direction.
Reproducibility
See Repeatability
Residual Unbalance
Zero measurand sensing element output
Resolution
The magnitude of output step changes as measurand is continuously varied over the range.
Resonance
Amplified vibrations of transducer components, within a narrow frequency band, observable in the output as a vibration applied along a specific transducer axis.
Resonant Frequency
The input frequency at which a transducer responds with maximum output amplitude. If there is more than one frequency the lowest is the resonant frequency
Response Time
The length of time required for the output of a transducer to rise to a value normally specified as 98 % of the value of a step change in measurand expressed in milliseconds.
Rise Time
The length of time required for the output of a transducer to rise from a small specified percentage of it's final value to a large specified percentage of it's final value as a result of a step change in the measurand.
Room Conditions
Normal specified ambient conditions. Normally 77 F + or - 18 F, 90 % RH, and 29 + or - 3 in Hg.

S
Sealed Gage Pressures (PSISG)
The pressure sensor is zeroed at atmosphere pressure. Mostly used in higher pressure applications such as hydraulic pressures.

Self-Heating
Internal heating as a result of electrical energy dissipated within the transducer.
Sensing Element
The part of the sensing element that responds directly to the measurand.
Sensitivity
The ratio of the change in transducer output to a change in the value of the measurand.
Sensitivity Shift
A change in the slope of the calibration curve due to a change in sensitivity.
Sensor
Instrumentation device, such as transducer.
Sound Pressure Level (SPL)
a unit that is 20 times the logarithm to the base 10 of the ratio of the pressure of the measured sound to the reference pressure of 20 micronewtons per square meter.
Span
The algebraic difference between the limits of range.
Stability
The ability of a transducer to retain its performance characteristics for relatively long period of time. Normally expressed in % FSO.
Static Calibration
A calibration performed under room conditions and in the absence of any vibration, shock, or acceleration.
Static Error Band
See Error Band.

T
Temperature Error Band
The error band applicable to increased or decrease environmental temperature usually expressed in % FSO/ 100 F.
Temperature Range, Compensated
See Temperature range, operating. Compensated temperature range is the interval of temperature range that was considered when designing compensation module for a specific transducer.
Temperature Range, Fluid
The rang for temperatures of the measured fluid, when it is not the ambient within which operation of the transducer is intended, and all specific tolerances for the temperature error band apply.
Temperature Range, Operating
The range of temperatures, given by their extremes, within which the transducer is designed to operate with no permanent damage to the transducer.
Thermal Coefficient of Resistance (TCR)
The relative change in resistance of a conductor or semiconductor per unit change in temperature over a stated range of temperature normally expressed in ohms per degree F or C.
Thermal Compensation
The addition of circuitry to alter output changed by temperature error back toward specified values at room temperature.
Thermal Sensitivity Shift
The sensitivity change due to changes of the ambient temperature from room temperature (design conditions) toward the limits of the operating temperature range.
Thermal Zero Shift
The zero measurand transducer output shift due to changes of the ambient temperature from room temperature to the specified limits of the operating temperature range.
Transducer
A device which provides a usable output in response to a specified measurand.
Transient Response
The response of a transducer to a step change in measurand. It is indicated by Time Constant, Ringing Period, and Response Time.
Transverse Acceleration
An acceleration perpendicular to the sensitive axis of the transducer.

U, V
Vibration Error
The maximum change in output, at any measurand value within the specified range, when vibration levels of specified amplitude and range of frequencies are applied to the transducer along specified axes.
Vibration Sensitivity
See Vibration error.

W, X, Y, Z
Warm-up Period
The period of time required from the time the excitation voltage is applied to the transducer until the output of the unit is within the specified tolerances for the applied measurand.
Weight
Weight of the transducer normally not including any portion that varies such as cables.