Identification of ships moving in formation by HFSWR using an ISAR cross-range imaging algorithm

Abstract

ABSTRACT High-frequency surface wave radar (HFSWR) has been widely used for ship detection to improve human marine activities. However, the azimuthal resolution is a major challenge for ship detection in HFSWR. Synthetic aperture technology can improve azimuthal resolution, which is different from increasing the size of the antenna array directly in practice. A new method to improve HFSWR azimuthal resolution for ships moving in formation is proposed. The proposed method extends inverse synthetic aperture radar (ISAR) cross-range imaging method to HFSWR, allowing ships in formation to be distinguished from each other in the cross-range domain. In the framework of HFSWR cross-range imaging, the motion of the ship formation is regarded as a rotating turntable by motion compensation. Based on the turntable configuration, the relationship between the cross-range domain and Doppler frequency can be built precisely. Then, the cross-range profile is obtained from the echo data by Fourier transform, and the cross-range spacing between ships can be estimated by the cross-range scaling. The simulated results demonstrate the effectiveness of the proposed method. The present work provides a new idea to improve the azimuthal resolution of HFSWR.