The sensor is a device or component that is used to transform a non-electrical quantities (physics and chemistry) to the amount of electricity that can be analyzed with a particular electrical circuit. There are some terms that need to be considered, namely the mistake (error), accuracy (accuracy), sensitivity (sensitivity), repeabilitas (repeability), hysteresis (hysteresis), linearity (linearity). The term errors (error) is defined as the difference between the actual value of the variable and the value of the measurement variable.
Often the actual value is unknown. For certain cases, the accuracy will show the range / bound probability of the true value. The term accuracy (accuracy) is used to determine kesaahan (error) the expected maximum amount of a tool in the measurement. There are several types of accuracy, namely:
1. Against the measured variables
For example, the accuracy in the measurement of temperature is 2 ° C, means that there are inaccuracies (uncertainty) of 2 ° C at any temperature values measured.
2. Against the percentage of readings of an instrument Full Scale
For example, an accuracy of 0.5% FS (Full Scale) on the meter with 5 V Full Scale, meaning inaccuracies in is 0.025 volts.
3. With respect to the percentage of span (rangekemampuan measuring instruments)
For example if a device measuring 3% of span for pressure measurement in the range of 20-50 psi, the accuracy was increased (0:03) (50-20) = 0.9 psi.
The term sensitivity (sensitivity) is defined as the change in the output of the instrument to any changes in the smallest input. High sensitivity is very desirable because if the change in output that occur when subjected to a small input, then the measurement will be more easily carried out. For example, if the temperature sensor sensitivity of 5 mV / ° C means any change in input 1 o C will appear at 5 mV output.
The term repeabilitas (repeability) is defined as a measurement of how well the resulting output when given the same input several times.
The term hysteresis (hysteresis) is defined as the difference in output that occurs between ascending input provision and administration of a large input value decreases with the same input. Is one indicator of repeatability.
Figure 2.21 Graph hysteresis
The term linearity (linearity) is defined as the relationship between output and input can be realized in a straight line equation. Linearity is highly desirable because all calculations can be done with ease if the sensor can be realized in a straight line equation.