Calibration of the RADARSAT SWB processor at the Alaska SAR Facility

Abstract

Calibration of the RADARSAT ScanSAR Wide B (SWB) processor at the Alaska SAR Facility (ASF) was completed at the end of 1998, making ASF one of the world's first synthetic aperture radar (SAR) processing facilities to distribute calibrated ScanSAR data to its users. SWB is one of several imaging modes onboard Canada's RADARSAT C-band SAR satellite. In the SWB beam-mode, wide-swath coverage of 450 km is achieved by combining four overlapping beams each about 150 km in range. To meet the requirements for absolute radiometric calibration error of +/-2 dB and relative calibration error of +/-0.5 dB, the authors used external calibration data of the Amazon rain forest. Absolute location accuracy requirements (+/-500 m) were verified using corner reflectors and U.S. Department of Defense coastline data. Results show radiometric and geometric calibration for the ASF RADARSAT SWB processor meet specifications. Image quality issues such as scalloping and beam overlap regions are discussed, as are several software tools that allow users to more effectively utilize SWB data.