CHIRP Z-TRANSFORM BASED SPECAN APPROACH FOR PHASE-PRESERVING SCANSAR IMAGE GENERATION

The scan mode synthetic aperture radar (ScanSAR) image impulse respons e is derived in the time domain, and particular attention is given to the analysis of the phase, which is important for several applications , and especially in interferometric ScanSAR systems. A new algorithm f or phase-preserving azimuth focusing of ScanSAR data, that extends the basic SPECAN procedure, is presented. The proposed algorithm avoids t he interpolation step needed to achieve constant azimuth pixel spacing by replacing the standard Fourier transform used in the SPECAN proced ure with an appropriate chirp z-transform. The relationship between th e modified SPECAN algorithm and the standard range-Doppler approach is also discussed. Experiments on real and simulated data are carried ou t to validate the theory.