S. G. Lichansky - Ph.D. (Eng.), Leading Research Scientist, JSC «Concern «Vega». E-mail: mail@vega.su

The improved-accuracy algorithm for high-resolution (1,0-0,5 m) SAR image synthesis in Spotlight mode in spacebased SAR is considered here. The highest reachable resolution depends of spectrum width of emitting pulses. Suppose that the bands used in this SAR are X, C or S. This algorithm is based on Stolt transform essential modification taking into account the terms of any degree of Taylor series representing range migration law and variations of these terms within scene limits not only by range - and by azimuth too. Taking into account of variation by range-azimuth of only first order of the terms of any degree allows transformation of SAR image integral into two-dimensional convolution. Used in this algorithm approximation SAR image integral representation by fast convergent polynomial series by range output variable allows to take into account and compensate nonlinear variation of migration law within scene by range in second order. The appropriate representation of two-dimensional integration procedure as two consequent one-dimensional integration procedures is providing fast algorithmic realization. The modified Omega-KA algorithm is called as Omega-KA-M. The Omega-KA-M algorithm is 2000-4000 times faster then well known back projection algorithm providing almost the same accuracy. The explicit calculation formulae of a set of the secondary ballistic coefficients that appear in the exact integral formula expressing a complex radar image through a complex hologram of the surveillance interval in the Spotlight mode are obtained. The input calculation data is the primary ballistic data, that is a Taylor vector coefficients set (until the fifth order) of a spaceship trajectory in the center of the surveillance interval, and the look parameters. These formulae use the look parameters and the ballistic data as input data. The stage-by-stage description of the appropriate algorithms is given.