Azimuth Ambiguity Mitigation in SAR

Kurzfassung

Azimuth ambiguities occur during the acquisition of SAR data as alias effects and overlap with the useful signal, thus degrading its quality. In the case of data recorded with the F-SAR system of DLR, strong, point-like scatterers cause the worst azimuth ambiguities. They become visible as stains in the final images which are one product of SAR missions. A new method to mitigate azimuth ambiguities is proposed in this work. A matched filter for refocusing azimuth ambiguities is designed. In this process, the original point-like objects are restored from the stains. The energy of ambiguities originating from point like scatterers can then be removed with minimal impact on the non-ambiguous data. Therefore a masking operation was optimized. The algorithm was tested with data of the DLR’s F_SAR system and showed promising results. After the removal of the azimuth ambiguities, structures overlaid by the stains have become visible again. A mitigation of azimuth ambiguities is not only important for a good image quality but can also improve all subsequent tasks like interferometric data processing or classification tasks.