A Workstation For Ers-1 / J-ers-1 / Multifrequency Polarimetric Sar Calibration And Validation

Abstract

In view of the growing number of Synthetic Aperture Radar instruments flying (ERS-1, NASA DC8 SAR) or to be flown (JERS-1, SIR-C, RADARSAT) and considering commonalities in tools for Calibration/Validation, a Unix workstation dedicated to SAR engineering Calibration and Validation has been developed at ESTEC(XR1). The workstation software has been designed to be able to handle different data formats and to decode the engineering parameters of the instrument. The user has interactively access to a full range of display from full resolution images to images of the full swath in compressed format in order to select point or distributed targets for further analysis. Quality analysis part of the software is used on point targets to characterise the Impulse Response Function of the instrument: resolution, peak side lobe ratio, integrated sidelobe ratio and signal to background. Calibration part of the software corrects for polarimetric SAR instruments relative channel imbalance (amplitude and phase) and cross-talk using calibration targets and/or distributed targets. For both conventional SAR and polarimetric SAR absolute calibration constants might be derived from two integral methods or a peak estimation method. Quality analysis and calibration results from ESA ERS-1 SAR data are presented and equivalent results from NASA DC8 SAR are discussed.