Software for Processing RADARSAT ScanSAR Data Into Images

SAR Processing System ScanSAR Processor (SPS SSP) is a computer program that is used in the Alaska SAR Facility (ASF) to processes scanSAR downlink data from the RADARSAT (a Canadian Earth-observation satellite) into a suite of image data products. ["SAR" means "synthetic-aperture radar" and "scanSAR" means "scan-mode SAR."] SPS SSP can process data that have been generated in any of the four RADARSAT scanSAR modes in current use — two wide-swath modes (300 ≤ width ≤ 500 km) called "SWA" and "SWB" and two narrow-swath modes (width ≈ 300 km) called "SNA" and "SNB." The output images are projected in ground range or else geocoded in universal transverse Mercator, polar stereographic, or Lambert coordinates. At present, the only image data products that are calibrated are those of the SWB mode. Typically, an SWB image covers an area of about 500 by 500 km. SPS SSP is executed on an IBM PS-2 computer, which includes (1) a control workstation equipped with 128MB of random-access memory (RAM) and a 4GB hard disk and (2) as many as eight processing nodes, each equipped with 256MB of RAM and a 4GB hard disk. When all eight nodes are used, a typical SWB image frame can be computed in about 35 minutes.