<title>Clutter reduction and target detection enhancement using wavelet transform techniques</title>

Abstract

In this paper, a multichannel optical wavelet processor and a matching pursuit processor capable of enhancing the detection of cluttered targets are presented. Wavelet functions have zero-mean and are virtually band-pass filters. In many cases, targets and clutter are separable in the spatial spectral domain. Therefore, by selecting wavelet functions that represent features of targets but are insensitive to that of clutter, targets can be extracted from the input scene while clutter is suppressed. Due to dyadic sampling, a multichannel optical wavelet processor with a limited number of channels can detect regions of interest for different targets. With matching pursuit decomposition. features of targets are extracted and represented in a few wavelets known as coherent structure: whereas clutter and noise are diluted across the dictionary. Clutter and noise can then be effectively removed from the signal by a simple thresholding operation. A time-frequency energy distribution can be derived from matching pursuit decomposition, which contains no interference terms and thus clearly characterizes the input signal in the time-frequency plane. Optical architectures of these processors are described. Simulated and experimental results are provided.

A reverse-SAR (R-SAR) algorithm for the detection of targets buried in ground clutter

“…resonant frequency f decreases with an increasing angle of 1 ␣. Also, for the case with ␣ s 0Њ, f can be approximately 1 …”

“…The ROIs are scanned with a sliding stencil, and the AOIs are collected and passed to the next stage for further processing. Let A denotes the colleck tion of AOIs belonging to a specific element ␥ of R. For k example, A is the set of AOIs belonging to ROI formed by 1 1 ␥ , the first element of R. Assuming that there are as many as 1 l AOIs in ROI , the AOIs in the ROI can be represented as 1 1 Ä 4 the elements of the set A s a , a , . .…”

“…, a . Therefore, the 1 1 1 1 2 1 l set of AOIs for all of the ROIs can be given by the set Ä 4 A s A , A , . .…”

Application of angular correlation function of clutter scattering and correlation imaging in target detection

“…Numerical simulations have been used to study the scattering properties [2], [3], and wavelet transform techniques have been used to separate targets from clutter [4]. Polarimetric measurements have been made for the detection of targets buried in a natural snowpack to enhance the visibility [5], and synthetic aperture radar (SAR) imaging has attracted great interest [5]- [7].…”