Data-Driven Antenna Delay Calibration for UWB Devices for Network Positioning

This study presents a real-time and fully automatic antenna delay calibration approach for ultrawideband (UWB) devices, which can be utilized to evaluate the combined delay of each UWB device used in the positioning system. Two estimators, a coarse estimator and a fine-tuning estimator, operate closely together in the calibration. The coarse estimator can determine a common coarse value for all devices involved in the calibration; the fine-tuning estimator continuously determines the optimal value for each device. More than three UWB devices can be calibrated simultaneously in real-time in the developed approach, making it a suitable solution for positioning applications with a large number of UWB devices. To evaluate the calibration accuracy of the proposed approach and verify the ranging accuracy and precision at different distances, experiments were conducted in an indoor office space and outdoors in an open space using universal UWB devices (DWM1001 from Decawave). The experimental results show that the proposed approach achieves a ranging precision of better than ±0.01 m within a base UWB network for each pair of devices and achieves a ranging accuracy and precision of better than ±0.05 m in a distance range from 1 to 25 m after calibration and bias correction for a remote/moving UWB device. Therefore, the developed approach is sufficient for UWB-based applications in which each UWB device must remain in a stationary state at the horizontal plane spanned by the devices in space to ensure the performance of the positioning system.