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.
Analog-to-Digital Reference Drift
Drift Phenomenon
Electronic measurement errors caused by temperature fluctuations in precision voltage references can degrade the accuracy of high-resolution data acquisition systems over time. This issue, formally known as analog-to-digital reference drift, appears as a slow change in the digital codes representing a constant analog input voltage. The drift is quantified in parts per million per degree Celsius and directly limits the long-term stability of calibration instruments.
Metrological Impact
A changing reference voltage alters the gain scale of the converter. This results in measurement errors that cannot be easily separated from actual sensor signal variations.
Compensation Method
System designers use stable bandgap reference circuits with low temperature coefficients to minimize these effects. In precision applications, the temperature of the reference circuit is monitored to apply digital compensation formulas. Regular calibration cycles against external primary voltage standards are necessary to verify that the analog-to-digital reference drift remains within allowable design tolerances.
Reference Calibration
Traceability is maintained by comparing the instrument response against a Josephson junction array or a certified secondary reference. This calibration process is conducted under controlled laboratory conditions where humidity and temperature are stabilized. The resulting adjustment coefficients are stored in non-volatile memory on the device.