Calibration of PalSAR polarimetric data
Anthony Freeman(1), Xiaoqing Pi(2) and Bruce Chapman(2)
(1) JPL/Caltech, MS 180 404, Pasadena, CA 91109, United States
(2) JPL/Caltech, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
JAXA’s PalSAR system produces L-Band SAR data of exceptional quality and performance. In this paper we introduce a new system calibration model for PalSAR data acquired in polarimetric mode. The system model accounts for cross-talk, channel imbalances and Faraday rotation. We establish that the cross-talk of the PalSAR system is at around – 40 dB, and that higher levels reported in the literature are due to uncorrected (small) amounts of Faraday rotation. This level of cross-talk is sufficiently low that it need not be corrected for in processing – it can be considered negligible.
We also show that the effect of Faraday rotation introduces an asymmetry into the measured scattering matrix which, if we can assume the system cross-talk is either reciprocal or negligible, allows full polarimetric calibration without the use of external targets such as corner reflectors. In this paper, we apply this technique to PalSAR polarimetric data, with expected low levels of Faraday rotation, to explore its limitations.
The work reported here was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.