Spectral 2-D image reconstruction in ISAR with linear frequency modulated signals

In this work inverse synthetic aperture radar (ISAR) signal processing of linear frequency modulated (LFM) signals for image retrieval is presented. The procedure comprises both range compression and azimuth compression. Most well-known image reconstruction methods are applied over the frequency space of ISAR signals. This technique requires implementing fast Fourier transforms (FFT) more than twice to the time record of ISAR returns. In this exploration, the image processing is accomplished over the time record of ISAR signal returns. In accessible literature, the ISAR signal processing is generally performed assuming that the target exhibits only rotational motion around its mass-center, while radial displacement of the object is always compensated. Unlike this conventional kinematic model, the ISAR signal processing is performed here by assuming arbitrary rectilinear movement of a target in the 2D coordinate system. By applying an analytical geometric approach, 2D ISAR geometry and kinematics needed for signal modeling are developed. The proposed spectral image reconstruction procedure is invariant to the trajectory parameters of the object. Numerical experiments proving the ability and accuracy of the spectral ISAR image reconstruction procedure are accomplished.