SCANSAR PROCESSING USING STANDARD HIGH-PRECISION SAR ALGORITHMS

Processing ScanSAR or burst-mode SAR data by standard high precision a lgorithms (e.g., range/Doppler, wavenumber domain, or chirp scaling) I s shown to be an interesting alternative to the normally used SPECAN ( or deramp) algorithm, Long burst trains with zeroes inserted into the interburst intervals can be processed coherently, This kind of process ing preserves the phase information of the data-an important aspect fo r ScanSAR interferometry. Due to the interference of the burst images the impulse response shows a periodic modulation that can be eliminate d by a subsequent low-pass filtering of the detected image. This strat egy allows an easy and safe adaptation of existing SAR processors to S canSAR data if throughput is not an issue, The images are automaticall y consistent with regular SAR mode images both with respect to geometr y and radiometry. The amount and diversity of the software for a multi mode SAR processor are reduced. The impulse response and transfer func tions of a burst-mode end-to-end system are derived, Special attention is drawn to the achievable image quality, the radiometric accuracy, a nd the effective number of looks, The scalloping effect known from bur st-mode systems can be controlled by the spectral weighting of the pro cessor transfer function, It is shown that the fact that the burst cyc le period is in general not an integer multiple of the sampling grid d istance does not complicate the algorithm, An image example using X-SA R data for simulation of a burst system is presented.