Airborne Synthetic Aperture Radar Imaging Algorithm

This paper discusses several questions about imaging algorithms of SAR. Mainly it discusses three imaging algorithms-Range-Doppler algorithm, wavenumber domain algorithm and Chirp Scaling algorithm. Still it discusses the assistant processing algorithms of imaging algorithms - Doppler centroid estimation algorithms and autofocus algorithms.Range-Doppler algorithm is a one dimensional algorithm. Wavenumber domain algorithm and Chirp Scaling algorithm are two dimensional algorithms. This paper discusses their theory and processing flow. To these three algorithms, based on the algorithm of vertical side-looking SAR, this paper dicusses the algorithm improvement of small and large squint side-looking SAR. And to these three algorithms, simulation is made to analyze them.The used value of Doppler centroid influence the imaging result very much, so it must be estimated precisely. The estimating methods contain time domain method and frequency domain method. Time-frequency analysis method can be used to improve estimating precision. This paper discusses the theory of these algorithms, analyze the influence of noise. Processing of raw data is made using these algorithms. To the phenomena of PRF-ambiguity, this paper discusses the method of PRF-ambiguity resolving by wavelength diversity. Simulation is made to analyze this algorithm.Autofocus algorithm is used to reduce second and higher rank phase error in the image. This paper discusses the subaperture correlation method and the phase gradient autofocus algorithm. Raw data processing or simulation is made to analyze these algorithms.