Ultra-micro Vibration Measurement Method Using CW Doppler Radar

As a non-contact vibration measurement technology, microwave radar is widely used in vital sign monitoring, structure health monitoring and precision instrument measurement. Although significant progress has been made, the continuous wave (CW) Doppler radar has inherent defects in ultra-micro vibration measurement due to the DC offset problem, which is challenging to be solved by the common circle fitting method with orthogonal baseband signals. In this paper, based on the Doppler phase demodulation algorithms, a pre-calculation method, creating a long arc of circle fitting by sliding the radar front-end in advanced, is proposed to accurately estimate the DC offset. Theoretical analysis and experimental results were provided for demonstrating our proposed method, which show that the ultramicro vibration measurement of 5μm can be realized.