Research on In-pulse Compensation Method for Imaging Ship Targets in FMCW-ISAR

Abstract

Given its advantages of low cost, low weight, and low power consumption, Frequency Modulated Continuous Wave-Inverse Synthetic Aperture Radar (FMCW-ISAR) has been widely used for imaging many kinds of targets. Since the FMCW signal can be regarded as a pulse signal whose duty ratio is one and pulse duration is relatively long, the motion of targets usually cannot be neglected. In this circumstance, the stop-go assumption is not valid, so ISAR images obtained using the traditional Range-Doppler (R-D) procedure exhibit two-dimensional blurring, which results in decreased resolution. In this paper, we investigate the blur problems of FMCW-ISAR in imaging ship targets, and construct a target motion model. Then, we analyze the influence of the in-pulse motion component in range profiles and final images. We propose a corresponding in-pulse compensation method to improve the resolution of ISAR images. A comparison with the imaging results of real measured echo data verifies the effectiveness of the proposed method in diminishing the 1-D-profile broadening and improving image quality.

Keywords

• Frequency Modulated Continuous Wave-Inverse Synthetic Aperture Radar (FMCW-ISAR)
• Imaging ship targets
• Stop-go assumption
• In-pulse compensation