Overview of current technologies for through-the-wall-surveillance

摘要

This paper discusses the state-of-the-art in through-the-wall surveillance technology (TWS) and examines the detector performances as a function of TWS application. This state-of-the-art is the most exhaustive possible, from the centimetre non-imaging system, to the submillimetre imaging system. This is followed by a review of the various functions and the results which can be expected from a TWS system depending on the situation and the applications (law enforcement and civil security). Then, different key parameters of a TWS imaging system are studied and discussed according to the applications. Reasons for the choice of wavelength are considered. This appears to be the most important parameter for improving the sensitivity (image contrast), the spatial resolution and the size of the system. Detector performances (noise equivalent power or noise temperature) are also examined as a function of the detection mode (heterodyne or direct) and the imaging system (passive or active).