A low complexity ISAR image autofocusing technique

In this paper we propose an Inverse Synthetic Aperture Radar (ISAR) autofocusing technique based on very simple operations like Fast Fourier Transform (FFT) and minimisation of the Euclidean distance between one-dimensional functions. The technique represents a good compromise between the image focusing capability and the computational complexity and it is composed of two algorithms: 1) the initialisation algonthm, whose task is to provide raw estimates of the two motion parameters which are necessary for the image focusing; 2) the optimisation algorithm, that improves the estimates given by the initialisation algorithm until the required accuracy is obtained. The computational complexity of the method is given by evaluating the number of complex operations required to focus image.