Interferometric Processing of ScanSAR Data Using Stripmap Processor: New Insights From Coregistration

Processing scanning synthetic aperture radar (ScanSAR) data using a stripmap processor, which is called full-aperture processing, has been the choice of many researchers. ScanSAR data are known to require very high azimuth coregistration precision which is usually achieved by a geometrical coregistration followed by a spectral diversity coregistration on the ScanSAR burst. However, for full-aperture processing, since individual bursts are no longer available for spectral diversity coregistration, the cross-correlation method in practice is still used to coregister ScanSAR data as stripmap data. We analyze the azimuth coregistration precision requirement of full-aperture processing and find that its requirement can be significantly relaxed. This is confirmed by a number of experiments, including simulations and real data experiments whose results are in good agreement with each other. An additional experiment on the cross-correlation method supports its use in full-aperture processing. Concluding from the experimental results, we further propose a simple method to evaluate the azimuth coregistration precision requirement for practical use. Finally, we present examples with ALOS-2 ScanSAR data.