A Novel Imaging Algorithm Based on Keystone Transform for Heliborne Forward-moving RoSAR System

Abstract

This paper deals with the issue of high-resolution imaging with the Heliborne forward-moving rotary synthetic aperture radar (RoSAR) system. RoSAR is a new type of SAR system, which uses the rotation of radar antenna to obtain azimuth synthetic aperture. In the forward RoSAR imaging geometric model, there is not only the azimuth velocity of antenna scanning but also the forward velocity of the platform. Therefore, the variation of target slant distance process reflects more complex spatial variation characteristics in the spectrum of the echo signal. A modified imaging algorithm based on the Keystone transforms is proposed for the Heliborne forward RoSAR system. With the forward-moving RoSAR imaging configuration, the relationship between the platform forward movement and the space-variant characteristics of the spectrum is given to construct the corresponding phase compensation function. A modified second-order keystone transform is used to correct the space-variant range cell migration term, meanwhile, the range-variant distortion in azimuth is removed by using the Chirp Z transform. Interpolation is not involved in this proposed algorithm, and its feasibility is verified by the simulation experiments.