Multipath model and exploitation in through-the-wall radar and urban sensing

Abstract

We establish the multipath model which encompasses the target and its multipath "ghosts" in urban and through-thewall synthetic aperture radar (SAR). The focused downrange and crossrange locations of multipath ghosts are derived and validated using numerical and experimental data. The multipath model permits an implementation of a multipath exploitation algorithm, which maps each target ghost to its corresponding true target location. In doing so, the proposed algorithm improves the radar system performance by aiding in ameliorating the false positives in the original SAR image as well as increasing the SNR at the target locations, culminating in enhanced behind the wall target detection and localization.

Multipath Exploitation in Through-Wall Radar Imaging Via Point Spread Functions

“…The analysis presented here improves on the results presented in [19], with regard to, the multipath modeling, multipath ghost focusing locations, and the techniques used in exploiting the multipath itself. Particular improvements w.r.t [19] will be noted subsequently.…”

“…The freespace ghost location estimates are used to initialize the NLS. Both these techniques provide multipath ghost location estimates which are superior to those derived in [19], and are shown in this paper. Targets do not manifest as spheres, rather their shape is dictated by the PSF.…”

“…The objective here unlike [14]- [18], but identical to [19] is in reduction of false positives and improving the SCR at the target location by association and mapping of the multipath SAR ghosts, and comprises the multipath exploitation procedure. The analysis presented here improves on the results presented in [19], with regard to, the multipath modeling, multipath ghost focusing locations, and the techniques used in exploiting the multipath itself. Particular improvements w.r.t [19] will be noted subsequently.…”

“…In our opinion, the Householder transformation provides a general and reconfigurable practical implementation for modelling specular multipath in reflective geometries incorporating different radar-target scenarios. As it stands analytically, the model in [19] is not amenable to handle multiple reflections and non-rectangular geometries without further tedious analysis. Using this Householder model, we derive techniques to estimate the locations where the multipath manifests as ghosts in the SAR image.…”

“…Targets do not manifest as spheres, rather their shape is dictated by the PSF. In [19], spherical weighting was used to map the multipath ghosts. Hence the technique in [19] could map clutter in the vicinity of the multipath ghosts, and in certain other cases, may not map the multipath ghost completely to its associated target position.…”