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.
Transfer Function Polynomial
Mathematical Curve
Higher-order algebraic equations express non-linear relationships between physical input stimuli and digitized sensor electrical outputs across specified operating ranges. A transfer function polynomial provides the mathematical framework for converting raw analog-to-digital converter counts into calibrated physical units. This equation models sensor non-linearity and thermal cross-sensitivity to deliver linearized output data.
The scope of this function covers mathematical sensor mapping, excluding digital signal filtering and communications protocols.
Polynomial Order
Calibration fitting procedures determine equation coefficients by evaluating sensor response across multiple reference points. A second-order polynomial corrects primary non-linear curvature, while third-order or fourth-order terms compensate for complex higher-order thermal dependencies. Increasing polynomial order improves curve-fitting accuracy across wide operating ranges but increases microprocessor calculation overhead and risk of runaway oscillation between calibration points.
Optimal coefficient determination balances mathematical residual errors against computational memory limits.
Correction Execution
Embedded firmware evaluates the algebraic series in real time to translate raw transducer signals into linear values. Applying a transfer function polynomial corrects physical sensor non-linearities before outputting data to industrial control networks.
Calibration Certificate
Metrological standards require documentation of exact polynomial order, coefficient values and fitting residual uncertainties. Calibration software saves these calculated coefficients directly into non-volatile sensor memory during factory testing. Test certificates cite the polynomial parameters and maximum fitting error to prove calibration integrity.