Data-adaptive motion compensation for synthetic aperture LADAR

In this paper, we discuss the application of the spatial correlation algorithm (SCA) (Attia and Steinberg, 1989; Attia, 1993; Attia, 1994), and some of its variants, to synthetic aperture LADAR (SAL) imaging. These algorithms (which derive the required phase corrections from range-resolved LADAR clutter received by the SAL sensor) are very robust, computationally efficient, perform very well in the presence of large uncorrelated phase errors, and do not require dominant scatterers of opportunity. Performance and limitations of the basic SCA are discussed. Dependence of the accuracy of the resulting phase corrections on the SNR per pulse and number of range cells available for estimating the corrections is presented in considerable detail. The impact of residual uncorrected phase errors on image SNR and dynamic range is statistically evaluated taking into account the total number of pulses coherently combined along the imaging baseline. Also, a method for exploiting special features of 3D interferometric SAL imaging for the purpose of improving phase correction accuracy is introduced.