Implementation of Fast Focusing Algorithm for Uwb Stepped- Frequency Gpr Sar Imaging

This paper discusses a fast and efficient focusing algorithm for ultra wideband (UWB) stepped-frequency continuouswave (SFCW) side-looking SAR image formation. Conventional SFCW SAR focusing algorithms are mostly based on the matched filter concept. Their frequency-domain implementation is burdensome. In this paper we present a more rapid and efficient algorithm for real-time and automatic UWB SFCW SAR imaging, especially for UWB groundpenetrating radar applications. The algorithm contains three key elements: two transforms and one automatic mapping of the coordinates. The processing and imaging are carried out automatically once the geometry and system parameters are given. The increased performance and efficiency of the algorithm is demonstrated using simulated UWB SFCW data acquired from a 2D target area over a 3D measurement geometry. For the raw data matrix with the size of 940 times 880 complex data points, the processing and imaging time (including upsampling procedure for data array in both range and azimuthal directions) takes 58 seconds in a Pentium III 900 MHz PC.