本文選題：彈載合成孔徑雷達(dá)　切入點：大斜視角成像　出處：《電子科技大學(xué)》2014年碩士論文

【摘要】：眾所周知,合成孔徑雷達(dá)(Synthetic Aperture Radar,SAR)能夠進(jìn)行距離向和方位向的二維成像,其成像模式是利用電磁波進(jìn)行主動成像,因此可以不受外界天氣環(huán)境的影響獲取高分辨率雷達(dá)圖像,目前SAR成像已經(jīng)很成熟的應(yīng)用在星載和機(jī)載平臺上,但是在彈載平臺上應(yīng)用還不太成熟。SAR成像獲取的是距離向和方位向的二維信號,與傳統(tǒng)的紅外成像、激光成像和一維距離成像相比,其具有得天獨厚的優(yōu)勢。具體表現(xiàn)在以下幾點:其一,可以不受日光輻射、云霧遮擋和其他惡劣天氣條件的影響而進(jìn)行全天候全天時成像;其二,具有一定的穿透能力,選擇合適的頻段,SAR可以穿透一些天然植被、人工偽裝,從而可以探測到偽裝的裝甲車、坦克和導(dǎo)彈發(fā)射井等目標(biāo);其三,由于SAR導(dǎo)引頭具有方位向信息,因此其能夠提供豐富的目標(biāo)電磁信息,得到散射點的強度和幅度等電磁散射信息,而一維距離成像無法實現(xiàn)這樣的目的。鑒于此,本文對彈載合成孔徑雷達(dá)的斜視成像算法進(jìn)行了研究,研究的主要內(nèi)容如下:1.通過對機(jī)載SAR正側(cè)視成像算法進(jìn)行推廣,研究了彈載SAR平飛階段大斜視成像算法,斜視角最大可以達(dá)到50°。該算法首先對瞬時斜距方程進(jìn)行研究分析,利用駐定相位原理推導(dǎo)出這種模式條件下的二維頻域表達(dá)式,結(jié)合時域距離走動校正方法,給出了改進(jìn)的距離多普勒算法,并用MATLAB對此算法進(jìn)行了驗證仿真,證明算法的有效性。2.研究了彈載SAR俯沖下降階段(方位向和垂直向存在速度和加速度)和曲線規(guī)避階段(方位向、距離向和垂直向存在速度和加速度)正側(cè)視及斜視成像算法。算法首先對彈載模式下的瞬時斜距進(jìn)行分析,然后利用泰勒級數(shù)展開和級數(shù)反演的方法推導(dǎo)了出兩種條件下的二維頻域表達(dá)式,最后在二維頻域?qū)π盘栠M(jìn)行相應(yīng)的處理,并用MATLAB對該算法進(jìn)行了仿真驗證,證明了算法的可行性。3.設(shè)計了一套SAR成像仿真軟件。利用Matcom軟件將Visual C++和MATLAB進(jìn)行相關(guān)級聯(lián),實現(xiàn)聯(lián)合編程。該成像仿真軟件很好地利用了Visual C++的可視化編程能力和MATLAB比較強大的計算能力,并且在成像的時候能夠擺脫對MATLAB環(huán)境的依賴,具有很好的移植性。最后概括了本文的研究內(nèi)容以及完成的內(nèi)容,指出研究課題過程中存在一些不足、需要改進(jìn)的地方和需要解決的問題。
[Abstract]:It is well known that synthetic Aperture radar (SAR) can perform two dimensional imaging in the range and azimuth directions. Its imaging mode is to use electromagnetic waves for active imaging, so that high resolution radar images can be obtained without the influence of the external weather environment.At present, SAR imaging has been used in spaceborne and airborne platforms, but it is not very mature in missile-borne platform. What we can get is the two-dimensional signal in range and azimuth direction, and the traditional infrared imaging.Compared with one-dimensional range imaging, laser imaging has unique advantages.It is shown in the following aspects: first, all-weather all-weather imaging can be carried out without the influence of solar radiation, fog and clouds, and other adverse weather conditions; and second, it has a certain penetration capability.Selecting the appropriate frequency band can penetrate some natural vegetation and artificially camouflage, so as to detect camouflaged armored vehicles, tanks and missile silos, etc. Third, because the SAR seeker has azimuth information,Therefore, it can provide abundant electromagnetic information of the target and obtain the electromagnetic scattering information such as the intensity and amplitude of the scattering point, which can not be achieved by one-dimensional range imaging.In view of this, the strabismus imaging algorithm of missile-borne synthetic aperture radar (SAR) is studied in this paper. The main contents of the research are as follows: 1.By popularizing the forward side imaging algorithm of airborne SAR, a large squint imaging algorithm for projectile-borne SAR is studied. The maximum oblique angle can reach 50 擄.Firstly, the instantaneous slant distance equation is studied and analyzed, and the expression of two-dimensional frequency domain under this mode is derived by using the stationary phase principle. The improved range Doppler algorithm is presented in combination with the time domain range walk correction method.The algorithm is verified by MATLAB, and the validity of the algorithm is proved. 2. 2.In this paper, the forward and squint imaging algorithms for projectile borne SAR subduction and descent stages (azimuth and vertical velocity and acceleration) and curve evading (azimuth, range and vertical velocity and acceleration) are studied.The algorithm firstly analyzes the instantaneous oblique distance in the projectile mode, and then derives the expression of the two-dimensional frequency domain under two conditions by using Taylor series expansion and series inversion method. Finally, the signal is processed in the two-dimensional frequency domain.The algorithm is verified by MATLAB, and the feasibility of the algorithm is proved. 3. 3.A set of SAR imaging simulation software is designed.Visual C and MATLAB are concatenated by Matcom software to realize joint programming.The imaging simulation software makes good use of the visual programming ability of Visual C and the powerful computing power of MATLAB, and can get rid of the dependence on MATLAB environment when imaging, so it has good portability.Finally, this paper summarizes the research content and the finished content, points out that there are some shortcomings in the course of the research, the place that needs to be improved and the problems that need to be solved.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN957.52
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本文編號：1728492