RADARSAT-1 image quality and calibration — a continuing success

The Canadian earth observation satellite, RADARSAT-1 was launched on November 4, 1995 with the first image acquired on November 28 of that year. After commissioning it was put into routine operation on April 1, 1996. Since then more than four years of successful operation have been completed, utilizing data for their intended applications. Significant effort has been extended in the provision of radiometrically and geometrically calibrated products to users by the Canadian Data Processing Facility (CDPF). Particular emphasis has been on the maintenance of image quality and calibration as monitored using images of the Amazon Rainforest and of the RADARSAT-1 Precision Transponders (RPT). This first part of the paper will review the image quality and calibration evolution of RADARSAT-1, complementing previously presented reviews on this subject. Data will be given on various image quality parameters related to impulse response, location error, antenna pattern and noise equivalent measures, and on calibration accuracy as achieved to date. Recent work on calibration and image quality improvements for ScanSAR products are also presented. The latter part of the paper describes methodologies developed for maintenance of radiometric calibration performance of RADARSAT-1, including a statistical technique useful for early detection of radiometric problems associated with single calibrated beams.