Imaging Experiments from Phase-Corrupted Airborne L-SAR Data

For the lack of high precision inertial measurement system, the experimental airborne L-band SAR system was badly affected by random phase error induced by motion instability. The resultant SAR images derived from the L-SAR system were out of focus by conventional SAR signal processing and imaging method. It is necessary to estimate and correct phase errors for high precision SAR imaging. As a prospective scheme to refocus these images, the phase gradient autofocus (PGA) algorithm was tested in the SAR imaging processing. The effectiveness of PGA algorithm was tested not only for isolated point scatter scene, but also for various distributed-object scenes to verify its performance. Particularly, a near-range scene, a mid-range scene, and a far-range scene were tested. Comparisons between images before refocusing and after PGA refocusing were made.