There are a lot of good sensors these days and many are ‘good enough’ out of the box for many non-critical applications. But in order to achieve the best possible accuracy, a sensor should be calibrated in the system where it will be used. This is because:
No sensor is perfect.
Sample to sample manufacturing variations mean that even two sensors from the same manufacturer production run may yield slightly different readings.
Differences in sensor design mean two different sensors may respond differently in similar conditions. This is especially true of ‘indirect’ sensors that calculate a measurement based on one or more actual measurements of some different, but related parameter.
Sensors subject to heat, cold, shock, humidity etc. during storage, shipment and/or assembly may show a change in response.
Some sensor technologies ‘age’ and their response will naturally change over time – requiring periodic re-calibration.
The Sensor is only one component in the measurement system. For example:
With analog sensors, your ADC is part of the measurement system and subject to variability as well.
Temperature measurements are subject to thermal gradients between the sensor and the measurement point.
Light and color sensors can be affected by spectral distribution, ambient light, specular reflections and other optical phenomena.
Inertial sensors are sensitive to alignment with the system being measured
What makes a good sensor?
The two most important characteristic of a sensor are:
Precision – The ideal sensor will always produce the same output for the same input.
Resolution – A good sensor will be able to reliably detect small changes in the measured parameter.
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