Question

Sensor Specification:

1- What's the parameter related to how close your sensor readings are from a reference method readings?

2- What's the parameter related to the dispersion of your sensor's multiple readings in a single simple?

Answer 1

Accuracy: The accuracy of the sensor is the maximum difference that will exist between the actual value (which must be measured by a primary or good secondary standard) and the indicated value at the output of the sensor. Again, the accuracy can be expressed either as a percentage of full scale or in absolute terms.

The sensitivity is then defined as the ratio between the output signal and measured property. For example, if a sensor measures temperature and has a voltage output, the sensitivity is a constant with the units [V/K]. The sensitivity is the slope of the transfer function.

A sensor's sensitivity indicates how much the sensor's output changes when the input quantity being measured changes.

Some sensors can also affect what they measure; for instance, a room temperature thermometer inserted into a hot cup of liquid cools the liquid while the liquid heats the thermometer.

Sensors are usually designed to have a small effect on what is measured; making the sensor smaller often improves this and may introduce other advantages.

Some of the most common sources of measurement uncertainties and deviations are

• Noise (thermal, quantization)
• Production (spread)
• Influencing parameters (temperature, stress)
• Calibration (calibration deviation/quantization)
• Lifetime drifts (aging)
• External sources of deviation (Strayfields, EMI)
• Sensor system faults.

Definition of Reliability and Unreliability:
The reliability of a sensor system acc. [6] is defined as the ability of a prod-
uct to perform a required function at or below a stated failure rate for a given
period of time. We further define the required function as correctly providing
measurement results within the specification limits at specified conditions (e.g.:
temperature, supply-voltage, lifetime). In engineering a more often used term is
unreliability which is the probability of a sensor system providing measurement
value outside the specification (failures).