【摘要】：調(diào)頻連續(xù)波(Frequency Modulated Continuous Wave,FMCW)合成孔徑雷達(dá)(Synthetic Aperture Radar,SAR)不僅具有全天時(shí)、全天候和高分辨率等優(yōu)點(diǎn),而且具有重量輕、體積小、造價(jià)低和功耗低等特點(diǎn),因此,FMCW SAR適裝于多種探測平臺上,甚至是小型無人機(jī)平臺,它在戰(zhàn)場偵查等軍事應(yīng)用和資源遙感等民用中都具有重要的應(yīng)用前景。同時(shí),FMCW SAR系統(tǒng)通常采用連續(xù)發(fā)射信號和Dechirp接收體制,平臺的運(yùn)動(dòng)不能忽略,傳統(tǒng)脈沖式SAR體制中的“停-走-停”假設(shè)不再成立,其回波形式更為復(fù)雜,需要對FMCW SAR回波信號進(jìn)行分析,研究相應(yīng)的FMCW SAR成像和動(dòng)目標(biāo)檢測算法。因此,FMCW SAR成像與運(yùn)動(dòng)檢測方法研究是目前雷達(dá)信號處理的研究熱點(diǎn)和難點(diǎn),該方向研究具有重要的理論意義和應(yīng)用價(jià)值。本文首先建立FMCW SAR回波信號模型,研究了斜視模式下的FMCW SAR成像算法。其次,建立FMCW SAR動(dòng)目標(biāo)檢測的回波模型,論述了FMCW SAR動(dòng)目標(biāo)檢測方法。然后,考慮到廣域運(yùn)動(dòng)目標(biāo)顯示(Ground Moving Target Indication,GMTI)具有觀測區(qū)域廣、重訪率高且對分辨率要求不高等特點(diǎn),可以完成對觀測場景的快速監(jiān)視與偵查,是目前地面目標(biāo)檢測技術(shù)的研究重點(diǎn),因此,本文對FMCW SAR體制下廣域GMTI處理算法進(jìn)行深入研究。最后,本文通過仿真實(shí)驗(yàn)數(shù)據(jù)處理對相關(guān)的FMCW SAR成像與廣域GMTI方法進(jìn)行了驗(yàn)證,主要工作總結(jié)如下:(1)首先建立FMCW SAR的回波模型,詳細(xì)分析了FMCW SAR的信號特點(diǎn)和雷達(dá)工作原理,并闡述了FMCW SAR與脈沖式SAR的差別;然后,分析斜視下FMCW SAR的信號特性,提出一種有效的斜視FMCW SAR成像算法;最后,利用仿真實(shí)驗(yàn)驗(yàn)證了該算法的有效性。(2)建立FMCW SAR動(dòng)目標(biāo)檢測的回波模型,對動(dòng)目標(biāo)信號進(jìn)行分析,結(jié)合多普勒頻移補(bǔ)償和DPCA技術(shù)等對動(dòng)目標(biāo)進(jìn)行檢測和粗成像,將動(dòng)目標(biāo)信息進(jìn)行提取,并反變換到其原始數(shù)據(jù),進(jìn)行二次成像聚焦處理,通過基于多普勒頻移補(bǔ)償、方位去斜、模糊數(shù)估計(jì)和Keystone變換等聯(lián)合處理方法,獲取聚焦良好的動(dòng)目標(biāo)成像結(jié)果。并通過仿真實(shí)驗(yàn)驗(yàn)證了該動(dòng)目標(biāo)檢測與成像方法的有效性。(3)首先建立FMCW廣域GMTI動(dòng)目標(biāo)信號模型,深入地分析FMCW-DBS成像原理及成像條件。其次,利用DBS成像技術(shù)獲得各波位的目標(biāo)成像結(jié)果,并對各波位子圖像進(jìn)行基于快速相關(guān)法的圖像拼接和坐標(biāo)轉(zhuǎn)換處理;接著,通過偏置相位天線(Displaced Phase center Anenna,DPCA)和恒虛警率(Constant False-Alarm Rate,CFAR)技術(shù)完成雜波抑制和動(dòng)目標(biāo)的檢測;然后,利用干涉相位法完成動(dòng)目標(biāo)的角域定位,并將定位結(jié)果標(biāo)定在上述成像結(jié)果中。最后,利用仿真數(shù)據(jù)處理驗(yàn)證該方法的有效性。
[Abstract]:FM CW (Frequency Modulated Continuous Wave,FMCW (Synthetic Aperture Radar,SAR) not only has the advantages of all-weather, all-weather and high resolution, but also has the characteristics of light weight, small size, low cost and low power consumption. FMCW SAR is suitable for a variety of detection platforms, even small unmanned aerial vehicles (UAVs). It has an important application prospect in military applications such as battlefield investigation and remote sensing of resources and other civilian applications. At the same time, the, FMCW SAR system usually adopts the continuous transmitting signal and the Dechirp receiving system, the motion of the platform cannot be ignored, the hypothesis of "stop-walk-stop" in the traditional pulse SAR system is no longer valid, and its echo form is more complicated. The FMCW SAR echo signal needs to be analyzed, and the corresponding FMCW SAR imaging and moving target detection algorithms are studied. Therefore, the research on, FMCW SAR imaging and motion detection is a hotspot and difficulty in radar signal processing at present, and the research in this direction has important theoretical significance and application value. Firstly, the FMCW SAR echo signal model is established, and the FMCW SAR imaging algorithm in squint mode is studied. Secondly, the echo model of FMCW SAR moving target detection is established, and the FMCW SAR moving target detection method is discussed. Then, considering that the wide-area moving object display (Ground Moving Target Indication,GMTI) has the characteristics of wide observation area, high revisit rate and low resolution, it can complete the rapid monitoring and investigation of the observation scene. It is the focus of research on ground target detection technology at present. Therefore, in this paper, the wide-area GMTI processing algorithm under the FMCW SAR system is deeply studied. Finally, the related FMCW SAR imaging and wide-area GMTI methods are verified by simulation data processing. The main work is summarized as follows: (1) first, the echo model of FMCW SAR is established. The signal characteristics of FMCW SAR and the working principle of radar are analyzed in detail, and the difference between FMCW SAR and pulse SAR is expounded. Then, the signal characteristics of FMCW SAR under squint are analyzed, and an effective squint FMCW SAR imaging algorithm is proposed. Finally, the validity of the algorithm is verified by simulation experiments. (2) the echo model of FMCW SAR moving target detection is established, the moving target signal is analyzed, and the moving target detection and coarse imaging are carried out by combining Doppler frequency shift compensation and DPCA technology. The moving target information is extracted and inversely transformed into its original data, then the secondary imaging focus processing is carried out. The joint processing methods are based on Doppler frequency shift compensation, azimuth declination, fuzzy number estimation and Keystone transform, etc. The imaging results of moving target with good focus are obtained. The effectiveness of the proposed method is verified by simulation experiments. (3) first, the FMCW wide-area GMTI moving target signal model is established, and the imaging principle and imaging conditions of FMCW-DBS are analyzed deeply. Secondly, the DBS imaging technology is used to obtain the target imaging results of each wave position, and the image stitching and coordinate conversion processing based on the fast correlation method are carried out for the image of each wave position. Secondly, clutter suppression and moving target detection are accomplished by bias phase antenna (Displaced Phase center Anenna,DPCA) and constant false alarm rate (Constant False-Alarm Rate,CFAR) techniques. Then, the interferometric phase method is used to locate the moving target in the angular domain, and the localization results are calibrated in the above imaging results. Finally, simulation data processing is used to verify the effectiveness of the proposed method.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TN957.52

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