||Radar Doppler has various applications in both military and civil aspect. The target moving parameters such as moving direction, moving velocity and so on can be well estimated through the analysis of radar Doppler effects. A new research called micro-Doppler which is proposed by the famous scholar Victor C. Chen was developed on the basis of micro motion model of objects.|
Since the human beings and the other creatures usually walk or run with a constant velocity, stride and gait frequency, there are some micro-Doppler signatures on their spectrums. Human gait detection and characteristic extraction mainly utilize the human’s walking dynamic features to modulate the radar echo phase, use time-frequency analysis method to obtain the spectrum, and extract the micro-Doppler signature of human gait from spectrum.
Through wall surveillance (TWS) is a kind of detection technology which can penetrate walls and other obstacles. With the ability of through-obstacle detection, TWS has been playing an important role in military reconnaissance, counter-terrorism, hostage rescue, earthquake casualty search and so on.
In this study, the micro-Doppler effect of the vibration and rotation is firstly discussed which is depend on the specific micro motion, and followed by the tool of time-frequency analysis. A gait echo model is proposed, which represents the rotation angles, displacements and relative phase relationship of joints, scatterers and the instantaneous Radar Cross Section (RCS). Finally, micro Doppler is combined with TWS for the feasibility of human gait direction determination.
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