A simple method for CAL/VAL of multi-aspect polarimetric PI-SAR images

Ya-Qiu Jin(1)

(1) Fudan University, 220 Handan Road, 200433 Shanghai, China


A set of 4-aspect Pi-SAR images in a square-loop flying at X band over Sendai City, Japan (the flights are indicated by the numbers, No. 8708, 8709, 8710, and 8711) is studied for target reconstruction. To implement this reconstruction, a simple method of first calibrating multi-aspect data is presented. It requires that at least one aspect is calibrated beforehand, and other aspects are then calibrated with respect to this calibrated aspect. A natural object, such as flat bare ground, is usually chosen as a reference target, which is expected to preserve identical scattering for all aspects. Thereafter, the channel imbalance factors are estimated from distribution of the phase difference and amplitude ratio of co-polarized, hh and vv, echoes of the reference target, and are then used to compensate the whole SAR images. Calibration of cross-talk effect is performed in conventional way. The calibration fidelity is proved by comparing the polarimetric signatures and the de-orientation parameters of the SAR images before and after calibration. This approach is successfully applied to calibration/validation (CAL/VAL) of 4-aspect airborne Pi-SAR data for target reconstruction mission. Another potential application is calibration of descending data using the calibrated ascending data, or vice versa.



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