The Application of the Hilbert-Huang Transform in Through-wall Life Detection with UWB Impulse Radar

Abstract

Hilbert-Huang Transformation (HHT) is a powerful tool for nonlinear and non- stationary data analysis. In this paper, a dataset using an ultra-wide (UWB) impulse radar system with central frequency of 1 GHz was collected for life motion detection behind a cinder block wall. To extract the information of life motions such as breathing and heartbeats from the raw data, we flrst applied the empirical mode decomposition (EMD), the flrst step of HHT to decompose the signal (background signal included) into a family of the intrinsic mode func- tions (IMFs). We then apply Hilbert spectral analysis (HSA) to get the frequency spectra of difierent IMFs. After dividing by the spectrum of the background radar record (equivalent to de-convolving the background record in the time domain), we found that breathing appear as a spectral peak at 0.2{0.4Hz and heart beating appears as 1.0{1.2Hz. This is coinciding with real condition. Our preliminary results show that the HHT technique provides signiflcant assistance in signal processing for the detection of human targets behind opaque obstacles.