Phase Calibration of Tomographic SAR data using volumetric natural targets

International audienceA fundamental requirement for TomoSAR processing is to have precise knowledge of the platform position along the 2D synthetic aperture. This requirement is not easily met in the case where the 2D aperture is formed by collecting different flight lines in a repeat-pass fashion, which is the typical case of airborne and spaceborne TomoSAR. Subwavelength platform position errors give rise to residual phase screens among different passes, which hinder coherent focusing in the 3D space. The employment of volumetric scatterers in the calibration process is enabled by the Phase Linking algorithm, which allows to represent them as equivalent phase centers. A cross-check of the results from simultaneous P- and L-Band acquisitions from the TropiSAR data-set indicates that the dispersion of the retrieved flight trajectories is limited to a few millimeters