Interferometric SAR acquisitions: Frequency ADapter for Interferometric applications (FADI) technique for enhanced performance

Abstract:
One of the most important applications of SAR Earth Observation systems is related to interferometric products (e.g. generation of topographic information of the sensed area, change detection, etc.). Due to specific satellite pointing performance in some cases the interferometric applications can be limited. Thanks to the “Frequency Adapter for Interferometric Applications” innovative processing, presented in this paper, it will be possible to increase the interferometric performance. Current processing algorithms use a single processing centroid for both focusing and radiometric equalization (i.e. for the whitening filter) and are based on the hypothesis that this processing centroid must be the same one of the physical acquisition. According to the FADI technique, two distinct Doppler centroids are envisaged. If the same Doppler centroid is used to focus two images (master and slave, or a series of N images), the term causing decorrelation is cancelled out and the two images preserve coherence. On the other hand, for the equalization of the radiometric pattern, the different Doppler centroid values estimated in each original image should be used. The novel technology offers the possibility of obtaining radiometrically corrected images with maximum spectral overlap, and thus with maximum coherence. The technique is applicable to any SAR mode, and in particular to burst mode (e.g. Ping-Pong and ScanSAR).