【作者】 张娟；

【导师】 刘峥；

【作者基本信息】 西安电子科技大学 ， 信号与信息处理， 2011， 硕士

【摘要】 传统雷达的任务主要是目标探测和定位,近年来,雷达功能逐渐增加,一个重要的应用是雷达成像技术。合成孔径雷达通过合成孔径原理实现方位高分辨,通过宽带信号实现距离高分辨。对于雷达成像的研究目前大多基于线性调频信号,本文将研究基于频率步进雷达信号的成像算法,它可以通过发射一组载频线性跳变的相参脉冲,获得等效的大带宽和高距离分辨力,通过方位综合,获得高方位分辨率,最终实现步进频雷达的合成孔径成像。本文考虑的步进频雷达信号是在不同的慢时间发射不同频率的信号,最后通过综合所接收到的回波信号实现雷达成像。与基于线性调频信号的成像方法相似,该成像方法需要进行方位合成和距离走动校正,而不同点是其不同频率分量的回波信号在方位维具有一个固定已知的位移,成像的关键就是补偿方位位移。本文首先简单介绍了步进频率雷达信号的距离域合成方法,包括脉冲合成原理,运动补偿以及像拼接方法,随后介绍了合成孔径雷达(SAR)成像原理与典型成像算法,最后利用毫米波步进频雷达测量系统,重点研究了步进频率SAR成像,结合步进频率SAR雷达目标回波的系统响应函数在方位维具有平移不变性,提出一种有效的步进频成像算法。更多还原

【Abstract】 A fundamental task of a conventional radar is to detect and localize radar targets. In recent years, more potential functions of radar are explored, such as a most importantone- radar imaging. Synthetic Aperture Radar (SAR)achieves a high azimuth resolution in virtue of the synthetic aperture principle and a high range resolution by transmitting wideband signal. Most of researches on radar imaging are based on linear frequency modulation (LFM) signals. In this work, how to image with a stepped frequency radarwill be studied. By transmitting a series of pulses with carrier frequencies linearly separated, a high bandwidth and a high range resolution can be achieved. In association with azimuthal synthesizing to achieve a high azimuthal resolution, synthetic aperture radar imaging can be finally achieved by a stepped frequency radar.The stepped frequency signal under consideration here transmits during flying a monochromatic narrowband pulse each time and then receives its echoed signals. All of the received signals are finally synthesized to obtain a radar image. Similar to radar imaging based on an LFM signal, radar imaging using an stepped frequency signal would perform azimuthal synthesis and range mitigation compensation. A difference is that echoed signals of different frequencies have different azimuthal displacements known a priori from reference locations, and a key point to image is to compensate the azimuthal displacements for echoed signals of different frequencies.In this paper, the process of range profile of stepped frequency radar is briefly introduced, including pulse synthesis technique,motion compensation algorithm and profile spelling methods. Subsequently, fundamentals of synthetic aperture radar (SAR) and typical SAR algorithms are studied. Finally, SAR based on the SFR is studied. Based on a fact that radar target response keeps the same in the azimuthal dimension, an efficient SF SAR algorithm is proposed.更多还原