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Proceedings Paper

Time-frequency signatures based on a fuzzy-cluster representation as a means for automatic classification of targets buried underground
Author(s): Hans C. Strifors; Steffan Abrahamson; Anders Gustafsson; Guillermo C. Gaunaurd
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Paper Abstract

We study the backscattered echoes from selected targets that are extracted by an impulse radar system playing the role of a ground penetrating radar (GPR). The targets are metal and nonmetal objects buried to a selected depth in dry sand in an indoor sandbox. The recorded time-series data are analyzed in the joint time-frequency domain using a pseudo-Wigner distribution (PWD). These distributions with their extracted features in the two-dimensional time-frequency domain are viewed as the target signatures. To be useful for target identification purposes, a signature representation should display a 'sufficient' amount of distinguishing features, yet be robust enough to suppress the interference of noise contained in the received signals. Multiple scattering between a target and the surface of the ground is another obstacle for successful target recognition that time-frequency distributions could counteract by unveiling the time progression of the returned target information. We have previously demonstrated the merits of the PWD relative to various competing time-frequency distributions, in particular its capability of extracting a target's time-frequency signature when the target is buried at different depths. We have also used a classification method developed from the fuzzy C-means clustering technique to reduce the number and kind of features in the PWD signature templates. This is accomplished by converting the PWD signature into a point cluster representation and then reducing the cluster to a (smaller) number of cluster centers. This classification method has been further developed by associating a weight with each point in the cluster representation. We put the classification algorithm to a test against validation data taken from an additional set of returned echoes. The same targets are used but they are buried at a different location in the sand. Class membership of a target is then decided using a simple metric. The results of our investigation serve to assess the possibility of identifying subsurface targets using a GPR.

Paper Details

Date Published: 18 September 1998
PDF: 9 pages
Proc. SPIE 3371, Automatic Target Recognition VIII, (18 September 1998); doi: 10.1117/12.323875
Show Author Affiliations
Hans C. Strifors, Swedish Defence Research Establishment (Sweden)
Steffan Abrahamson, Swedish Defence Research Establishment (Sweden)
Anders Gustafsson, Swedish Defence Research Establishment (Sweden)
Guillermo C. Gaunaurd, Naval Surface Warfare Ctr. (United States)

Published in SPIE Proceedings Vol. 3371:
Automatic Target Recognition VIII
Firooz A. Sadjadi, Editor(s)

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