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measured value A number assigned to the variable
measured.
measured variable A variable whose value is measured;
also known as the measurand.
mechatronics Subject area focused on the interaction
between electrical and mechanical components of
devices and the control of such devices.
measurement The act of assigning a specific value to
the variable being measured.
metrology The science of weights and measures.
moir e patterns An optical effect resulting from
overlaying two dense grids that are displaced slightly
in space from one another.
monostable One-shot device that toggles on and then
off on a single voltage command.
moving coil transducer A sensor that uses a
displacement of a conductor in a magnetic field to
sense velocity.
multiplexer An input/output (I/O) switch having multiple
input signal lines but only one output signal line.
natural frequency The frequency of the free
oscillations of an undamped system.
noise An extraneous effect that imposes random
variations on the measured signal.
null mode Measuring method that balances a known
amount against an unknown amount to determine the
measured value.
Nyquist frequency One-half of the sample rate or
sampling frequency.
obstruction flow meter Device that measures flow rate
by the magnitude of the pressure drop arising by
purposefully creating an abrupt area change in the flow.
ohmmeter An instrument for measuring resistance.
open-loop control Type of control action that does not use
a sensor to measure the variable being controlled, such as
by controlling room lights using a light switch timer.
operating conditions Conditions of the test, including
all equipment settings, sensor locations, and
environmental conditions.
optical pyrometer Nonintrusive temperature
measurement device. Measurement is made through an
optical comparison.
orifice meter Flow meter consisting of a flat plate with a
hole in its center that fits between a pipe flange to
create a pressure drop proportional to flow rate; also
known as an orifice plate.
oscilloscope An instrument for measuring a timevarying voltage signal and displaying a trace; very
high frequency signals can be examined.
outlier A measured data point whose value falls outside
the range of reasonable probability.
output value The value indicated by the measurement
system.
output stage Stage of a measurement system that
indicates or records the measured value.
overall error Instrument uncertainty estimate based on
the square root of the sum of the squares (RSS) of the
uncertainties of all known instrument errors.
parallel communication Technique that transmits
information in groups of bits simultaneously.
parameter The value defined by some functional
relationship between variables related to the
measurement.
particle image velocimetry Optical method that
measures flow velocity by observing the distance
traveled by fluid particles per unit time suspended
within the fluid.
passband Range of frequencies over which the signal
amplitude is attenuated by no more than 3 dB. See
stopband.
Peltier effect Describes the reversible conversion of
energy from electrical to thermal when a current flows
through a junction of dissimilar materials.
phase shift A shift or offset between the input signal
and the output signal representing the measured signal;
may be expressed in terms of an angle.
photoelastic Describes a change in optical properties
with strain.
pitot-static pressure probe Device used to measure
dynamic pressure.
piezoresistance coefficient Constant that describes the
change in electrical resistance with applied strain.
Poisson’s ratio Ratio of lateral strain to axial strain.
pooled value Statistical value determined from separate
data sets, such as replications, that are subsequently
grouped together.
population The set representing all possible values for a
variable.
potentiometer Refers either to a variable resistor or to
an instrument for measuring small voltages with high
accuracy.
potentiometer transducer Variable electrical resistance
transducer for measurement of length or rotation angle.
precision The amount of dispersion expected with
repeated measurements; archaic term used to describe
the random uncertainty.
precision (instrument specification) Ultimate
performance claim of instrument repeatability based
on multiple tests conducted at multiple labs and on
multiple units.
precision error See random error. Archaic term no
longer used in measurements.
precision indicator Statistical measure that quantifies
the dispersion in a reported value.
precision interval Interval evaluated from data scatter
that defines the probable range of a statistical value
and ignoring the effects of systematic errors.
primary standard The defining value of a unit.
prover Flow meter calibration device using some
method placed in series with the candidate flow meter
Glossary 581
11:19:49 Page 581
measured value A number assigned to the variable
measured.
measured variable A variable whose value is measured;
also known as the measurand.
mechatronics Subject area focused on the interaction
between electrical and mechanical components of
devices and the control of such devices.
measurement The act of assigning a specific value to
the variable being measured.
metrology The science of weights and measures.
moir e patterns An optical effect resulting from
overlaying two dense grids that are displaced slightly
in space from one another.
monostable One-shot device that toggles on and then
off on a single voltage command.
moving coil transducer A sensor that uses a
displacement of a conductor in a magnetic field to
sense velocity.
multiplexer An input/output (I/O) switch having multiple
input signal lines but only one output signal line.
natural frequency The frequency of the free
oscillations of an undamped system.
noise An extraneous effect that imposes random
variations on the measured signal.
null mode Measuring method that balances a known
amount against an unknown amount to determine the
measured value.
Nyquist frequency One-half of the sample rate or
sampling frequency.
obstruction flow meter Device that measures flow rate
by the magnitude of the pressure drop arising by
purposefully creating an abrupt area change in the flow.
ohmmeter An instrument for measuring resistance.
open-loop control Type of control action that does not use
a sensor to measure the variable being controlled, such as
by controlling room lights using a light switch timer.
operating conditions Conditions of the test, including
all equipment settings, sensor locations, and
environmental conditions.
optical pyrometer Nonintrusive temperature
measurement device. Measurement is made through an
optical comparison.
orifice meter Flow meter consisting of a flat plate with a
hole in its center that fits between a pipe flange to
create a pressure drop proportional to flow rate; also
known as an orifice plate.
oscilloscope An instrument for measuring a timevarying voltage signal and displaying a trace; very
high frequency signals can be examined.
outlier A measured data point whose value falls outside
the range of reasonable probability.
output value The value indicated by the measurement
system.
output stage Stage of a measurement system that
indicates or records the measured value.
overall error Instrument uncertainty estimate based on
the square root of the sum of the squares (RSS) of the
uncertainties of all known instrument errors.
parallel communication Technique that transmits
information in groups of bits simultaneously.
parameter The value defined by some functional
relationship between variables related to the
measurement.
particle image velocimetry Optical method that
measures flow velocity by observing the distance
traveled by fluid particles per unit time suspended
within the fluid.
passband Range of frequencies over which the signal
amplitude is attenuated by no more than 3 dB. See
stopband.
Peltier effect Describes the reversible conversion of
energy from electrical to thermal when a current flows
through a junction of dissimilar materials.
phase shift A shift or offset between the input signal
and the output signal representing the measured signal;
may be expressed in terms of an angle.
photoelastic Describes a change in optical properties
with strain.
pitot-static pressure probe Device used to measure
dynamic pressure.
piezoresistance coefficient Constant that describes the
change in electrical resistance with applied strain.
Poisson’s ratio Ratio of lateral strain to axial strain.
pooled value Statistical value determined from separate
data sets, such as replications, that are subsequently
grouped together.
population The set representing all possible values for a
variable.
potentiometer Refers either to a variable resistor or to
an instrument for measuring small voltages with high
accuracy.
potentiometer transducer Variable electrical resistance
transducer for measurement of length or rotation angle.
precision The amount of dispersion expected with
repeated measurements; archaic term used to describe
the random uncertainty.
precision (instrument specification) Ultimate
performance claim of instrument repeatability based
on multiple tests conducted at multiple labs and on
multiple units.
precision error See random error. Archaic term no
longer used in measurements.
precision indicator Statistical measure that quantifies
the dispersion in a reported value.
precision interval Interval evaluated from data scatter
that defines the probable range of a statistical value
and ignoring the effects of systematic errors.
primary standard The defining value of a unit.
prover Flow meter calibration device using some
method placed in series with the candidate flow meter
Glossary 581