Passive–Active Synchronous Imaging Using Modulated Noise Waves

Pactive (passive + active) hybrid imaging, combining active and passive modes, is crucial for remote sensing and object detection. However, current techniques generally perform data or image-level fusion during post-processing, using physically separate systems. In this work, we propose a modulated noise-based pactive synchronous imaging (PASI) system that shares a receiver system and can generate both active and passive images simultaneously, which achieves hardware-level fusion. By modulating noise to illuminate the scene, we can simultaneously detect its thermal radiation and scattering properties with a radiometer receiver. Since the noises from the environment and the noise source are independent stationary random processes, a correlation-averaging operation is presented to divide the radiometric and scattering noises. Experimentally, we evaluated this concept by using a millimeter-wave radiometer and a noise source to realize the radiometric and scattering sensing for “hot,” “cold,” metallic, and absorbing-material objects. Through planar scanning imaging, the experimental image results demonstrate the feasibility of PASI in a scene illuminated by modulated noise.