Improved Vital Signal Detection Method Based on Multi‐Regions of Interest Joint Enhancement for 4D Through‐Wall Imaging Radar

Through‐wall imaging radar (TWIR) is equipped with large bandwidth and penetration characteristics and can be used for vital signal detection of people trapped under ruins after natural disasters. Aiming at the problem of low signal‐to‐noise ratio (SNR) and micro‐motion interference of vital signal behind obstacles, this paper proposes a vital signal detection method based on multiple regions of interest (multi‐ROI) joint enhancement for 4D TWIR. In the proposed method, high frame rate TWIR is used to image the human body behind the wall, and the position of the human joints is estimated through the posture recognition model, which can be used to determine the abdominal region. The dynamic time warping (DTW) method is used to select the ROI phase signal to construct a multichannel source vital signal matrix, and then, the clutter interference of the remaining limbs is eliminated. Combined with the subspace characteristics of vital signals, the adaptive nonstationary signal decomposition (ANSSD) is used to process the left singular matrix to eliminate the noise caused by micro‐motion, and the SNR of vital signal is further improved. The proposed method is compared with the traditional method. Visual images and quantitative results show that the output SNR and detection accuracy of the proposed method are further improved. The long‐term monitoring results are basically consistent with the true ECG value.