Change Detection and Enhanced Imaging of Vital Signs Based on Arc-Scanning SAR

Radar-based life imaging technology has been widely applied in both civilian and military fields. Arc-scanning synthetic aperture radar (AS-SAR) is an emerging radar system suitable for high-resolution imaging and monitoring small objects. In this article, AS-SAR is extensively applied for imaging and detection of human vital signs to simultaneously get SAR image of scenario and monitoring the vital signs. Due to the simultaneous micromotion of human vital signs and AS-SAR, vital signs are defocused in AS-SAR image and often masked by the clutters. Therefore, they are often in the low signal-to-clutter-noise ratio (SCNR) and hard to be detected. In this article, change detection (CD) methods based on subaperture image sequence of one measurement and coherent difference of two measurements are proposed to remove the background and improve the SCNR of vital signs. And then, vital signs enhanced imaging based on the modified coherent factor (CF) is applied to the image after CD processing to further improve SCNR. We employed a series of experiments, including scenarios of a vital simulator, single standing human, single lateral recumbent human, and multiple standing humans, to validate the proposed methods. The experimental results show that the proposed method can raise the SCNR of vital signs by more than 15 dB. These experimental results validated the AS-SAR system’s potential in the detection, identification, and interpretation of human targets.