高速运动目标一维成像研究

发布时间：2018-01-19 14:31

本文关键词： 高速运动目标一维成像运动补偿分数阶傅里叶变换 Wigner-Hough变换多项式相位变换　出处：《电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：一维距离像是目标上各散射点回波在雷达距离向的矢量叠加所形成的幅度分布图,可以反映出目标精细的物理结构,是目标识别的重要特征之一。由于目标的一维距离像计算量较小、实时性高、并且有很好的稳定性,因此有着重要的实用价值,在民用领域和军用领域都有广泛地应用。但是,当目标高速运动时,目标的一维距离像会变模糊,出现谱峰分裂、频谱展宽或畸变等现象。要得到目标清晰地一维距离像,必须对目标进行运动补偿以消除速度对成像的影响。本论文的主要研究内容如下:1.针对高速运动目标,研究了基于分数阶傅里叶变换(FrFT)的一维成像。LFM信号经FrFT后,在某一特定的分数阶域有很好的时频聚集性,表现为一峰值。本章采用了基于两步峰值搜索的FrFT,首先使用大步长搜索,估计出峰值的粗略值。然后进行小步长搜索,就可以得到峰值的精确值。最后根据峰值的位置信息就可以估计出LFM信号的参数。该方法有很高的参数估计精度,计算复杂度也比较小,并对噪声有很好的鲁棒性。并把该方法成功的应用于对高速运动目标的一维成像速度补偿中,估计出的调频率达到了很高的精度,取得了很好的成像效果。最后仿真验证了上述结论的正确性。2.研究了基于Wigner-Hough变换(WHT)的高速运动目标一维成像。WHT是Wigner-Ville分布(WVD)和Hough变换(HT)的结合,是一种重要的时频分析方法。LFM信号经WVD后映射为WVD平面上的直线,再进行Hough变换,即做直线的投影积分变换,会映射为WHT面上的峰值点,根据峰值点的位置信息就可以实现对高速运动目标一维距离像的速度补偿。该方法能很好的抑制交叉项和噪声的影响,有很高的参数估计精度,仿真实验取得了很好的一维成像效果。3.完成了基于离散多项式相位变换(DPT)的大加速度运动目标的一维成像研究。大加速度目标的回波可以看作是阶数为3的多项式相位信号(PPS)。利用DPT实现了对PPS的二阶项和三阶项系数的估计,求得的运动补偿因子有效地消除了回波中高次项对成像的影响。DPT法有很高的参数估计精度,对运动补偿后的信号做FFT可以得到目标清晰地一维距离像,仿真验证了该方法的有效性。最后采用乘积型高阶模糊函数法,解决了多分量PPS在PPT变换后的交叉项问题。
[Abstract]:One-dimensional range is the amplitude distribution map formed by the vector superposition of each scattering point echo in the radar range direction on the target, which can reflect the fine physical structure of the target. It is one of the important features of target recognition. Because of the small computation of one-dimensional range profile, high real-time and good stability, it has important practical value. It is widely used in civil and military fields. However, when the target moves at high speed, the one-dimensional range profile of the target will become blurred and spectrum peak splitting will occur. It is necessary to obtain a clear one-dimensional range profile of the target, such as spectrum broadening or distortion. It is necessary to compensate the target motion to eliminate the influence of velocity on the imaging. The main contents of this thesis are as follows: 1. Aiming at the high speed moving target. In this paper, one dimensional imaging. LFM signal based on fractional Fourier transform (FrFT) is studied. After FrFT, it has good time-frequency aggregation in a specific fractional order domain. In this chapter, FrFT based on two-step peak search is used to estimate the rough value of peak value, and then small step size search is carried out. Finally, the parameters of LFM signal can be estimated according to the position information of the peak value. This method has high parameter estimation accuracy and low computational complexity. The method is successfully applied to compensate the velocity of one dimensional imaging of high speed moving target, and the estimated frequency has a high accuracy. Good imaging effect has been achieved. Finally, the correctness of the above conclusions is verified by simulation. 2. The research is based on Wigner-Hough transform. The high speed moving target imaging. WHT is a combination of Wigner-Ville distribution and Hough transform. LFM signal is mapped to a straight line on the WVD plane by WVD, and then Hough transform, that is, the projection integral transformation of a straight line. It can be mapped to the peak point on the WHT surface, and according to the position information of the peak point, the velocity compensation of the one-dimensional range profile of the high speed moving target can be realized. This method can suppress the influence of crossover term and noise. It has high precision of parameter estimation. Good one-dimensional imaging effect is achieved by simulation. 3. DPT-based discrete polynomial phase transformation is completed. The echo of a large acceleration target can be regarded as a polynomial phase signal of order 3 / PPS). The second and third order coefficients of PPS are estimated by using DPT. The obtained motion compensation factor effectively eliminates the effect of the high order term in the echo. DPT method has a high precision of parameter estimation. One dimensional range profile of the target can be clearly obtained by FFT, and the effectiveness of the method is verified by simulation. Finally, the product high-order fuzzy function method is adopted. The cross term problem of multicomponent PPS after PPT transform is solved.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN957.52

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