Extracting Gyroscope Allan Deviation Asymptotes and Noise Parameters
Extracting Allan deviation noise parameters demands fitting logarithmic asymptote slopes across discrete cluster time intervals under steady thermal conditions.
Scale Factor
Proportionality Constant
Conversion of physical input quantities into proportional electrical units depends on a calibrated ratio constant within the transducer signal chain. In rate gyroscopes and accelerometers, scale factor represents the ratio of change in output signal to the change in physical input being measured. Units are typically expressed in millivolts per degree per second or digital counts per unit of acceleration.
Non-linearity across the operating range introduces measurement distortion when input dynamics approach full scale limits. Accurate baseline calibration ensures that physical motion translates linearly into digital engineering values.
Calibration Method
Precision rate table testing quantifies sensitivity coefficients by exposing the sensor to known positive and negative input velocities. Least-squares linear regression fits a straight line through multi-point measurement data to extract the primary scale factor slope. Deviations from this straight line define the non-linearity metric, expressed in parts per million of full scale.
Temperature chamber testing establishes compensation curves to correct sensitivity variations caused by component temperature shifts. Modern digital sensors store multi-point calibration coefficients in internal non-volatile memory registers.
Environmental Drift
Aging of internal optical paths or piezo-resistive elements causes long-term sensitivity degradation over operational life cycles. Mechanical stress on sensor packages alters internal structural geometry, shifting the baseline scale factor value.
Tolerance Boundary
Acceptance specifications mandate tight scale factor stability windows across operational temperature ranges. Verification routines confirm compliance by executing precision rotational tests following thermal shock exposure. Departure from specified sensitivity limits distorts calculated velocity vectors during dynamic vehicle maneuvers.