次軌道飛行器多通道合成孔徑雷達的航行船艦成像

Abstract

本研究提出一個次軌道飛行器多通道合成孔徑雷達，對航行中的船艦成像。為滿足高解析度、寬掃描區域的要求，雷達脈衝發射頻率須相對降低，由此衍生了頻譜混疊以及都普勒頻率不確定的問題。在本研究中，我們提出了相位匹配的方法以解決部分的頻譜混疊，再以多級壓縮感知技術解決頻譜混疊以及都普勒頻率不確定的問題。模擬結果包含以本篇論文提出的方法所產生的五艘類似船艦的雷達影像，同時試驗了各種不同的輸入訊號訊雜比的成像結果。最後我們以包括幾何匹配、強度匹配以及結構相似性來辨識產生雷達影像中的船艦類型。

A multi-channel synthetic aperture radar (SAR) on board a spaceplane orbiting near the top of the atmosphere is proposed to acquire images of cruising ships. Low pulse repetition frequency (PRF) is required for high-resolution wide-swath (HRWS) imaging, leading to inevitable problems of azimuth spectrum aliasing (ASA) and azimuth Doppler ambiguity (ADA). In this work, we propose a phase matching technique to solve the ASA problem in restoring the azimuth spectrum. A multi-stage compressive-sensing (CS) technique is also proposed to solve both ADA and ASA problems. Five similar types of cruising ship are simulated to verify the efficacy of the proposed approach, at different levels of signal-to-noise ratio. Indices of geometry match, intensity match, and structural similarity are used to identify different ships from the acquired SAR images.