Life signal extraction based on isophase in through-the-wall radar

Vital signs such as respiration and heart beating introduce micro-motions for stationary human targets. In this paper, an isophase based human life signal extraction approach is presented to detect human target inside buildings using a stepped-frequency through-the-wall radar. Firstly, the stationary human micro-motion model is established and the effect brought by the wall is analysed. Then the isophase line is associated with micro-motion human life signal in slow time range dimension. Finally, isophase line is extracted as a representation of life signal. Experimental results demonstrated that the proposed approach can extract life signal of stationary human correctly and accurately.