change in the output. The sensitivity error is the deviation from the ideal
slope of the sensor response curve.
ii. Sensor range corresponds to the maximum and minimum values that can be
measured. For example, a thermometer can operate in the range −40° to 60 °C,
which gives a span of 100 °C.
iii. Accuracy of a sensor is the smallest possible deviation from the most
probable or exact value of the measured quantity and refers to the degree of
reproducibility of a measurement. Thus, if a quantity is measured repeatedly,
an ideal sensor would yield the same output each time. But in effect, sensors
produce a range of output values distributed around the presumptive true
value.
iv. A sensor’s stability is its capacity to function according to the calibration
curve for a reasonable period.
v. Sensor offset error is the deviation that occurs when the output should be
zero or alternatively, the difference between the true and observed output
values, under specified conditions. The offset, such as nonlinearity, is readily
corrected for by digitalization.
vi. Linearity or nonlinearity of the calibration curve, dependent on the environmental conditions, affects the sensitivity of the measuring equipment,
even though linearization can be done digitally. The linearity of the transducer is the degree of deviation from the true curve, measured by a sensor in
relation to a straight line.
vii. Resolution of a sensor is the lowest input variation which causes a detectable
change in the output, which can be related to the input value. The resolution
can be expressed either in relation to the percentage of the entire scale or in
absolute terms.
viii. Sensor accuracy is the maximum difference between the true value (which
should be measured by a standard primary or a good secondary standard) and
the output value. Accuracy may be expressed as a percentage of full scale, or
in absolute terms.
ix. Hysteresis is due to different sensor output depending on the input value be
achieved by an increase or decrease of the measured quantity.
x. Sensor threshold is the lowest measurable quantity above zero and is usually
the result of friction in mechanical devices, for example, in the case of
anemometers cups.
xi. Repeatability is the degree of closeness between consecutive output measurements for a given input value under identical operating conditions.
Generally, this feature is quantified as a percentage of non-repeatability in the
measurement range.
xii. Measurement errors are either systematic or random. With systematic errors,
the error does not change between successive measurements. With random
errors, the errors vary between successive measurements, for example, due to
electronic noise, temperature fluctuation, operational error, environmental
disturbances, etc.
Annex A1: Instrumentation in Environmental Physics
317
slope of the sensor response curve.
ii. Sensor range corresponds to the maximum and minimum values that can be
measured. For example, a thermometer can operate in the range −40° to 60 °C,
which gives a span of 100 °C.
iii. Accuracy of a sensor is the smallest possible deviation from the most
probable or exact value of the measured quantity and refers to the degree of
reproducibility of a measurement. Thus, if a quantity is measured repeatedly,
an ideal sensor would yield the same output each time. But in effect, sensors
produce a range of output values distributed around the presumptive true
value.
iv. A sensor’s stability is its capacity to function according to the calibration
curve for a reasonable period.
v. Sensor offset error is the deviation that occurs when the output should be
zero or alternatively, the difference between the true and observed output
values, under specified conditions. The offset, such as nonlinearity, is readily
corrected for by digitalization.
vi. Linearity or nonlinearity of the calibration curve, dependent on the environmental conditions, affects the sensitivity of the measuring equipment,
even though linearization can be done digitally. The linearity of the transducer is the degree of deviation from the true curve, measured by a sensor in
relation to a straight line.
vii. Resolution of a sensor is the lowest input variation which causes a detectable
change in the output, which can be related to the input value. The resolution
can be expressed either in relation to the percentage of the entire scale or in
absolute terms.
viii. Sensor accuracy is the maximum difference between the true value (which
should be measured by a standard primary or a good secondary standard) and
the output value. Accuracy may be expressed as a percentage of full scale, or
in absolute terms.
ix. Hysteresis is due to different sensor output depending on the input value be
achieved by an increase or decrease of the measured quantity.
x. Sensor threshold is the lowest measurable quantity above zero and is usually
the result of friction in mechanical devices, for example, in the case of
anemometers cups.
xi. Repeatability is the degree of closeness between consecutive output measurements for a given input value under identical operating conditions.
Generally, this feature is quantified as a percentage of non-repeatability in the
measurement range.
xii. Measurement errors are either systematic or random. With systematic errors,
the error does not change between successive measurements. With random
errors, the errors vary between successive measurements, for example, due to
electronic noise, temperature fluctuation, operational error, environmental
disturbances, etc.
Annex A1: Instrumentation in Environmental Physics
317