A Low Signal-to-Clutter ISAR Imaging Method for Ship Targets Based on Multi-Aperture Rotation Alignment

By employing a multi-aperture rotation alignment method, the problems of sea clutter interference, non-stationary motion, and rotation error in ISAR imaging of ship targets under low signal-to-clutter ratios were solved, achieving high-precision ship target imaging and improving image focus and clarity.

CN122307548APending Publication Date: 2026-06-30HARBIN INST OF TECH
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
HARBIN INST OF TECH
Filing Date
2026-05-25
Publication Date
2026-06-30

AI Technical Summary

Technical Problem

In low signal-to-clutter ratio environments, ship target ISAR imaging faces challenges such as decreased image signal-to-clutter ratio due to the non-Gaussian heavy-tail characteristics of sea clutter, image defocusing and blurring due to non-stationary motion, and image structure misalignment due to sub-aperture rotation errors.

Method used

A multi-sub-aperture rotation alignment method is adopted, which eliminates the coupling between distance frequency and slow time through Keystone transform, uses sliding window technology to segment sub-aperture data, and combines rotation search alignment and geometric mean fusion to suppress sea clutter interference and correct rotation errors.

Benefits of technology

It improves the accuracy of ISAR imaging of ship targets, enhances the focus, contrast and outline sharpness of images, and can generate high-precision ISAR images in environments with extremely low signal-to-clutter ratios.

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Abstract

This invention relates to a low signal-to-clutter ratio ISAR imaging method for ship targets based on multi-aperture rotation alignment. Specifically, it relates to ISAR signal processing and imaging, and more specifically to a ship target ISAR imaging method. The purpose of this invention is to address the problem that existing methods cannot simultaneously solve non-stationary Doppler blurring, sub-aperture rotation errors, and strong clutter interference during the imaging process, leading to low accuracy in ship target ISAR imaging. This invention establishes an echo signal model of the three-dimensional motion of ship targets in a marine environment and introduces sea clutter interference. It utilizes Keystone transform combined with a minimum entropy phase autofocus algorithm to compensate for range migration and phase error in the pulse-compressed signal. The full-aperture observation data is divided into multiple sub-aperture data blocks to generate sub-image sequences. A screening threshold is introduced to select high-quality sub-frames. The rotation error of each preferred sub-image relative to the reference frame is estimated and resampled for correction. Finally, a geometric mean fusion algorithm is used to preserve the strong scattering point features of the target.
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