<title>Performance of VHF-band SAR change detection for wide-area surveillance of concealed ground targets</title>

Abstract

VHF-band SAR used in conjunction with change detection techniques has shown promising results for wide-area surveillance of ground targets . By using VHF-band frequencies both targets in the open as well as concealed by foliage may be detected. These detections occur with high probability and with a low false-alarm rate. VHF-band SAR is able to detect hidden targets because both foliage attenuation and clutter backscatter is small. The clutter is further repressed through the use of change detection, thus significantly reducing the false-alarm rate. Change detection techniques are well suited for VHF-band SAR since temporal decorrelation is small at these large wavelengths. The CARABAS-II system performed a data collection during the summer of 2002. The primary goal of this collection was to gather data to evaluate VHF-band SAR change detection performance under various operating conditions. This paper reports the results obtained. In general, the results show a VHF-band SAR system employing change detection can reliably and robustly detect truck-sized targets hidden in foliage. The detection performance does deteriorate under certain conditions. A significant reduction is found for near-grazing angles. Additionally, a significant performance loss is found for smaller-sized targets when the radar bandwidth is reduced.