MODULE 4: Performance Characteristics Flashcards
Examples of performance characteristics.
- accuracy
- precision
- resolution
- sensitivity
Allows the user to select the most suitable instrument for a specific measuring jobs.
Performance characteristics
Types of performance characteristics.
- Static characteristics
* Dynamic characteristics
Describes performances at room temperature conditions with very slow changes in measurement quantities.
STATIC CHARACTERISTICS
Defines as the characteristics describing the relationship between specified points when system variables are not changing.
STATIC CHARACTERISTICS
Refers to the behavior between the time that the input value changes and the time that the value given by the system or elements settles down to the steady state value.
DYNAMIC CHARACTERISTICS
Static characteristics:
- ACCURACY
- PRECISION
- REPEATABILITY
- REPRODUCIBILITY
- SENSITIVITY
- RESOLUTION/DISCRIMINATION
- STABILITY
- RANGE/SPAN
- THRESHOLD
- OUTPUT IMPEDANCE
- OFFSET
- DRIFT
The degree of exactness (closeness) of measurement compared to the expected (desired value).
ACCURACY
Is an indicator of how close the value given by the measurement system can be expected to be to the true value.
ACCURACY
Measure of consistency or repeatability of measurement, i.e. successive reading do not differ.
PRECISION
The ability of measurement system to give the same value for repeated measurements of the same value of variable.
REPEATABILITY
The ability of the system to give the same output when used with a constant input with the system or elements of the system being disconnected from its input and then reinstalled.
REPRODUCIBILITY
Indicates how much the output of an instrument system changes when the quantity being measured changes by given amount.
SENSITIVITY
Defined as the smallest change in the input signal that will cause a readable change in the output of the measuring system at its operating point.
RESOLUTION / DISCRIMINATION
The ability to give the same output when used to measure a constant input over a period of time.
STABILITY
The range of variable system is the limits between which the input can vary.
RANGE / SPAN
It is the minimum input for which the will be an output. Below this minimum input, instrument will read zero.
THRESHOLD
It is the smallest measurable input or first detectible output change.
THRESHOLD
The impedance across the sensor when it is giving electrical output.
OUTPUT IMPEDANCE
The reading of an instrument with zero input.
OFFSET
The change in the reading of an instrument of a fixed variable with time.
DRIFT
Is used for the difference between the result of the measurement and the true value of the quantity being measured.
M. ERROR
MEASURED VALUE—TRUE VALUE
ABSOLUTE ERROR
(MEASURED VALUE — TRUE VALUE) / (TRUE VALUE)
PERCENT ERROR
Characteristics that show the performance of an instrument.
Performance characteristics
