穿墙雷达快速BP和衍射层析成像重建技术研究

发布时间：2018-12-09 17:41

【摘要】：穿墙雷达成像作为一种新型透视成像技术,在反恐侦察、城市作战、灾后营救等领域有广泛应用。常见的成像技术有红外成像、热成像、超声波探测、可见光成像等。电磁波由于具有良好的传输穿透性,能够保证穿墙雷达精确获取非金属介质后待探测区域内的信息,从而成像。常见的穿墙雷达成像方法有后向投影算法、衍射层析算法、时间反转算法、压缩感知算法等。本文主要针对后向投影算法和衍射层析算法进行研究和改进。后向投影算法由于精确补偿电磁波在介质表面发生折射的优点成为穿墙雷达成像研究的热点。但其成像原理的核心为待成像区域每一成像点的延时-求和,因此后向投影算法在成像时需进行大量重复计算。传统后向投影成像算法无法做到快速准确地对墙后探测区域进行高质量成像,必须以牺牲时间为代价获得高分辨率成像。本文以非均匀快速傅里叶变换为基础,提出一种高效的穿墙雷达快速后向投影成像算法,能在不降低成像质量的前提下,大大缩短后向投影算成像重建时间,满足穿墙雷达系统实时成像场合的需求。随着穿墙雷达应用场景复杂度增加,传统单层墙体透视成像方法已经无法满足工程需求。本文从电磁逆散射原理出发,研究穿墙雷达衍射层析成像算法,根据平面多层格林函数谱域展开式和爆炸源模型,提出一种基于一阶Born近似的穿墙雷达多层媒质衍射层析成像算法,能对多层平面媒质后隐蔽目标进行快速准确成像。基于时域有限差分法的穿墙雷达全波电磁仿真数据验证了所提成像算法的正确性和有效性。
[Abstract]:Wall penetrating radar imaging, as a new type of perspective imaging technology, has been widely used in anti-terrorist reconnaissance, urban warfare, post-disaster rescue and other fields. Common imaging techniques include infrared imaging, thermal imaging, ultrasonic detection, visible light imaging and so on. Because of its good transmission and penetration, the electromagnetic wave can accurately obtain the information in the region to be detected after the non-metallic medium is detected by the penetrating radar. The common imaging methods of wall-penetrating radar include backward projection algorithm, diffraction tomography algorithm, time reversal algorithm, compression sensing algorithm and so on. In this paper, the backward projection algorithm and diffraction tomography algorithm are studied and improved. The backward projection algorithm has become a hot spot in the research of wall penetrating radar imaging because of the advantage of accurately compensating the refraction of electromagnetic wave on the dielectric surface. However, the core of its imaging principle is the time-summation of each imaging point in the region to be imaged, so the backward projection algorithm needs a large number of repeated calculations in the imaging process. The traditional backward projection imaging algorithm can not perform high quality imaging of the detection area behind the wall quickly and accurately, so high resolution imaging must be obtained at the expense of time. Based on the nonuniform fast Fourier transform (FFT), an efficient fast backward projection imaging algorithm for wall-penetrating radar is proposed in this paper, which can greatly shorten the reconstruction time of the back-projection imaging without reducing the imaging quality. It can meet the need of real-time imaging of penetrating radar system. With the increasing complexity of penetrating radar scene, the traditional single-layer wall perspective imaging method can not meet the needs of engineering. Based on the principle of electromagnetic inverse scattering, the diffraction tomography algorithm of penetrating wall radar is studied in this paper. According to the expansion of plane multilayer Green's function spectral domain and the model of explosion source, A multi-layer diffraction tomography algorithm based on first-order Born approximation is proposed for radar multilayer diffraction tomography, which can quickly and accurately image the hidden targets behind the multi-layer plane media. The validity and validity of the proposed imaging algorithm are verified by the full wave electromagnetic simulation data of the wall penetrating radar based on the finite-difference time-domain method (FDTD).
【学位授予单位】：沈阳航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN957.52

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