What Sensor Calibration Is and Why Readings Drift
Calibration maps sensor error against traceable standards, while drift stems from physical aging, mechanical strain, and environmental stress over time.
End-Point Non-Linearity
Measurement Deviation
Straight line approximation dictates the total divergence between the actual output of a sensor and the ideal reference line drawn between the zero and full scale output points. End-point non-linearity quantifies this error as the maximum deviation observed at any point along the signal range. Manufacturers calculate this value by forcing a straight line through the two extreme physical calibration points and observing how far the intermediate sensor response falls from that line.
Calibration records typically express this error as a percentage of the full scale output capacity.
Sensor Characteristic
Practical instrumentation requires a constant check against theoretical performance models to verify reliability in dynamic environments. The end-point non-linearity serves as a gauge for predicting signal distortion across the intended operation span. High error values indicate a lack of correlation between the input signal and the processed output signal over the mid-range of the sensor.
Calibration Procedure
Technicians adjust the gain and offset of a device to force the output to match the desired sensitivity at the start and end of the scale. This process eliminates specific types of errors while leaving the end-point non-linearity as an inherent property of the sensing material or the signal conversion circuitry. Adjustments during assembly minimize the deviation at the bounds but the curvature between these marks persists due to component tolerances.
Performance Constraint
Operational limits define the reliability of a sensing element when exposed to changing conditions that trigger non-linear responses. Designers select specific hardware based on the stated linearity tolerance because this figure defines the maximum expected error before the output reaches the hardware limits. Small differences between the sensor curve and the straight line facilitate predictable control in industrial feedback loops.
Final calibration reports provide a verification of the expected error bounds under controlled temperatures.