Efficient 3-dimensional imaging algorithm using PI extraction based RPM for quasi-far field UWB radars

Ultra-wide band (UWB) pulse radar has a definite advantage over optical ranging techniques in harsh optical environments, such as a dark smog or strong backlight. In security or rescue situations with blurry visibility, it is particularly promising for identifying human bodies. One of the most promising approaches for this type of application is the recently proposed range points migration (RPM) method, which is beneficial for non-parametric imaging and is robust in noisy or heavily interference situations. However, the original RPM requires a discretization of the direction of arrival (DOA) variables in its search operation. The resulting coarse discretization seriously degrades the imaging accuracy, particularly for 3-dimensional problems and quasi-far field observations (defined as more than 5 wavelengths). Then, in this approach, there is a severe trade-off between the amount of computation and accuracy. To overcome this difficulty, this paper proposes a more efficient RPM algorithm, where the extraction of the point of intersection (PI) of spheres is adopted. A distinct advantage of this method is that the accuracy is basically invariant to the observation range when avoiding the above discretization. Numerical simulations prove that our proposed RPM remarkably reduces the computation complexity while retaining imaging accuracy.