Interferometric Motion Sensing with a Single-Channel Radar Sensor Based on a Novel Calibration-Free Phase Demodulation Technique

The interferometric radar sensor is superior in detecting the relative displacement motions. The conventional motion-recovery techniques leverage the quadrature I/Q signals to reconstruct the phase information, where accurate calibration of the I/Q signals is a prerequisite. Accurate phase demodulation depends on the precision of signals calibration. Incorrect signals calibration and hardware imperfections may lead to false phase demodulation. In this paper, based on the signal segmentation and Hilbert transformation principle, a novel linear phase reconstruction technique is proposed, which not only involves a single receiver channel without bothering the I/Q signals but also gets rid of the I/Q signals calibration. Both simulation and experimental results show that the proposed single-channel demodulation (ScD) technique recreates the target motion without any phase ambiguity and improves the accuracy with an RMSE less than 0.01 mm, which is over 9 times than that of the other state-of-the-art approaches.