Accurate non-contact vibration amplitude retrieval using least squares estimation

An accurate non-contact amplitude retrieval of the periodic movement is proposed in this paper. Firstly, the backscattered signal of a vibrational target can be expanded as a series of harmonics whose amplitudes are determined by the vibration amplitude. Then, based on the least squares estimation, all the available harmonics are utilized to suppress the influence of the signal noise on the vibration measurement, so as to improve the accuracy of vibration amplitude retrieval. Finally, the Monte Carlo simulation is performed to validate the effectiveness in the case of low signal-to-noise ratio (-9dB). Accuracy of the new method in different cases of signal-to-noise ratio is also obtained. In addition, the real experimental data acquired by a 100GHz millimeter radar is used to test the performance of the proposed method, associated with a calibrator of vibration. In the experiment, a calibrator of vibration is 30m away from the radar. The results show the proposed method has better accuracy than the ones in the case of only one harmonic pair is used.