Interferometric Assessment of SAOCOM-1 TOPSAR Data

Satélite Argentino de Observación COn Microondas (SAOCOM-1) constellation operates in three acquisition modes: Stripmap (SM), Terrain Observation with Progressive Scans Synthetic Aperture Radar (TOPSAR) Narrow (TNA and TNB), and TOPSAR Wide (TW). Since repeat-pass SAOCOM-1 TOPSAR acquisitions are not synchronized, the generation of the related interferometric products is not guaranteed, as it happens instead for the synchronized repeat-pass TOPSAR acquisitions, such as those of Sentinel-1. In this work, we assess the suitability of SAOCOM-1 TOPSAR acquisitions for generating interferometric products. To this aim, we first discuss the constraints that must be fulfilled by the repeat-pass nonsynchronized TOPS acquisitions in order to make it feasible the generation of usable interferograms. Then, we verify whether SAOCOM-1 TOPSAR acquisitions fulfill these constraints. For this purpose, we present an analysis based on the use of a dataset composed by 18 TNB images relevant to a single subswath illuminating a region located in the southwest of Argentina. From this dataset, we were able to select 48 pairs that guarantee the spectral superposition needed for interferometric purposes. We verified that 50% of these 48 pairs fulfill the constraint required to avoid in the corresponding interferograms the presence of noncoherent azimuth stripes, whose azimuth extension depends on one side on the mis-synchronization percentage between the repeat-pass acquisitions and the other side on the overlapping percentage between adjacent bursts of the same acquisition. Summing up, the presented analysis proves the potential of SAOCOM-1 TOPSAR acquisitions to obtain interferometric products, despite the absence of bursts synchronization between repeat-pass acquisitions.