Self-calibration method for inductive coupling ceramic waveguide ultrasonic temperature measurement based on front-end crosstalk characteristics

High-temperature ultrasonic thermometry with detachable inductive readout can exhibit time-of-flight (TOF) bias from probe repositioning. We propose an Al₂O₃ ceramic-waveguide system using front-end electromagnetic crosstalk as an indicator of coupling state. A fixed nominal TOF-temperature inversion model is combined with RBF-SVR compensation using crosstalk energy and spectral centroid features. Developed using controlled coupling perturbations at 900 °C, the compensation model was transferred without retraining to independently acquired data at 1100 °C. At the 1100 °C furnace-reference condition, temperature RMSE decreased from 42.52 to 4.08 °C. In 20 random external-probe repositionings, the standard deviation of coupling-state mean errors decreased from 10.79 to 4.43 °C. Across 150 reliability-screened coupling conditions, mean condition-wise RMSE decreased from 41.59 to 3.01 °C and maximum RMSE from 59.71 to 7.37 °C. Additional thermal-cycle evaluation at 700, 900, 950, 1050, and 1100 °C using 31 predefined coupling conditions yielded TOF-bias prediction RMSEs of 0.04450–0.04617 μs without retraining. These results support crosstalk-based coupling-state self-sensing and compensation of TOF bias in detachable wireless ultrasonic thermometry.