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调频步进雷达信号及其合成孔径成像研究
Stepped-frequency Chirp Signal and Synthetic Aperture Radar Imaging Study
【作者】 李丽亚；
【导师】 吴顺君；
【作者基本信息】 西安电子科技大学 ， 信号与信息处理， 2006， 硕士
【摘要】 合成孔径雷达是的二维成像(距离和方位)雷达,其方位分辨率决定于合成孔径长短,而距离分辨率则借助于宽带信号的脉压技术。由于距离分辨率与信号的带宽成反比,要想获得距离向的高分辨率,就要求雷达的发射信号具有大带宽；实现大带宽的信号面临着技术上和方法上的巨大挑战,所以,雷达的高距离分辨只能借助于宽带与超宽带技术来实现。调频步进雷达信号的提出,为实现超大宽带雷达信号提供了新的技术途径。调频步进雷达信号由载频步进变化的线性调频子脉冲串构成,对其应用宽带合成技术可以获得距离高分辨。本文首先对调频步进信号进行分析,并给出了其模糊函数；接着讨论了两种宽带信号合成方法,即基于一般接收模式的时域宽带信号合成方法和基于解线性调频处理的时域信号合成方法,并且从一维距离像角度入手,进行了仿真实验,给出了实验结果；最后介绍了合成孔径雷达成像的原理和常用算法,阐述了调频步进信号照射下的合成孔径雷达成像原理,根据两种不同的宽带信号合成方法给出了两种不同处理方法,并进行了仿真实验,仿真结果证明了方法的可行性。同时对实测数据进行处理,其成像结果说明了方法的工程可实现性。
【Abstract】 SAR is an imaging radar in two dimensions (range and azimuth). The azimuth resolution depends on the length of the synthetic aperture, and the range resolution is decided by pulse compression of the large bandwidth signals. The range resolution is inverse proportional to the bandwidth of signal, so the radar signals must have large bandwidth in order to obtain the high range resolution. But there is a big challenge to obtain such signal. The technique of wideband and ultra-wideband can be used to get the high range resolution.The presents of the stepped-frequency Chirp radar signal provides a new solution to obtain ultra-wideband radar signals The stepped-frequency Chirp radar signal is composed of Chirp pluses which carrier frequencies are changed High range resolution is achieved by means of the synthetic bandwidth signal technique. Firstly, the stepped-frequency Chirp radar signal is analyzed and the ambiguity function is given. Secondly, two methods to combine bandwidth signal are discussed. One is based on the basal receive mode in time field and the other is based on the de-chirping operation in time field. Some experiments are done and some results of verification are given. Lastly, the theory and algorithms of synthetic aperture radar imaging is shown and the technique of the SAR using the stepped-frequency Chirp radar signal is put forward. Two different methods of the combined bandwidth signal bring two different ways of SAR imaging. Some experiments is done and some results verifies that the methods are feasible. The raw SAR data is processed and the result is shown that it can be achieved in projects.