Coupling suppression in human target detection via impulse through wall radar

In homeland security and disaster rescue applications, ultra-wide band (UWB) through-wall radar (TWR) is often adopted to determine human targets behind wall or buried in rubble. The task is full of challenge, because the weak echoes of human target and various kinds of strong interference such as environment clutter, noise, coupling namely antenna cross-talk and so on result in a low signal-to-clutter-and-noise ratio (SCNR). Especially when human target locates in the coupling range, serious coupling will cover the weak target echoes. In this paper, we focus on coupling removal in detection of human targets via an impulse TWR. In real systems, the presence of timing jitters in the un-ideal sampling clock destroys the correlation of received echo signals including coupling signal. Coupling signal is so strong that little residual because of timing jitter is comparable with human target echoes and could cause false alarm. Thus we first model timing jitter, and analyze its effect on coupling signals. Then we introduce a jitter compensation approach including amplitude and delay compensation to align coupling signals. Finally, the exponential average background subtraction (EABS) method is implemented to complete the coupling suppression. Through-wall experiments are presented and compared to verify the proposed approach.