MIMO与认知雷达波形设计理论与算法研究

发布时间：2018-06-24 18:34

  本文选题：MIMO雷达 + 认知雷达　； 参考：《电子科技大学》2014年博士论文

【摘要】：波形设计是MIMO雷达研究领域的一个关键问题,波形设计的好坏直接影响其性能。根据MIMO雷达所承担任务的不同,通过设计有针对性的MIMO波形能够提高雷达性能。因此,研究MIMO雷达波形设计相关的理论与算法具有重要意义及应用价值。同时,作为雷达研究领域的新热点,认知雷达因其特有的“接收到发射”的闭环结构,使得认知雷达具有更大的提高雷达性能的潜力。而波形设计是凸显雷达系统“认知”特性的一个必不可少的环节,当前,怎样设计波形提高认知雷达抑制干扰的能力也受到越来越多的学者的关注。针对MIMO雷达正交相位编码信号设计问题,遗传算法和模拟退火算法是提高自相关和互相关性能常用的优化设计方法,但是不同的应用背景对波形设计提出了针对性的要求。本文在保证低自相关旁瓣峰值和低互相关峰值的基础上,围绕波形还必须满足严格正交性以及具有零相关区域两种具体情况开展研究。目前,认知雷达波形的研究成果主要集中在任意波形,由于这些任意波形的包络不是恒定的,因此无法充分利用雷达发射机的效率。针对这一问题,本文以提高雷达性能(如目标检测概率)为设计目标,对认知雷达恒包络波形设计开展研究。本文主要针对MIMO雷达正交相位编码设计和认知雷达恒包络波形设计的一些关键技术问题进行研究,取得了一些有益的结论和成果。本文主要研究工作和创新点如下:1.提出了一种基于Hadamard矩阵的正交二相码优化设计方法。利用Hadamard矩阵的正交特性,设计的相位编码信号不但具有较低的自相关旁瓣峰值和互相关峰值,并且两两信号间还具有严格正交性,有利于改善雷达的目标测量精度和杂波对消效果。该方法仅需要较小的计算机存储空间就能够优化出较长的相位编码。因此,可以用于雷达超长相位编码序列的设计中。2.研究了基于序列二次规划(SQP)算法的类零相关正交相位编码优化设计方法。针对MIMO雷达目标检测性能是由收发波束形成后输出的综合脉压旁瓣水平直接决定这一问题,将发射信号的和(简称“和信号”)的模糊函数旁瓣特性引入目标函数中,利用该方法设计得到的相位编码在零相关区域不但具有超低的自相关旁瓣峰值和互相关峰值,并且和信号的模糊函数还具有高主副比和优良的多普勒容忍性。3.研究了波形旁瓣影响下的机载MIMO雷达杂波特性。对波形旁瓣影响下的机载MIMO雷达杂波回波进行建模,并且理论分析和公式推导了正交波形的自相关旁瓣和互相关对机载MIMO雷达杂波秩的影响。在机载MIMO雷达的应用背景下,得到了发射波形的自相关旁瓣和互相关会使得杂波秩明显增大的结论。4.针对认知雷达波形设计问题,分别以最大化信号匹配滤波器输出端信噪比(SNR)和信杂噪比(SCNR)为设计准则,研究了色噪声下和杂波下的恒包络波形设计方法。该方法以待优化信号的能量谱密度(ESD)在最小均方误差意义下逼近最优的ESD为目标函数,采用SQP算法进行相位编码信号的优化设计。与传统发射信号如线性调频信号(LFM)相比,利用该方法设计得到的相位编码信号能够有效提高输出的SNR或SCNR。特别地,针对色噪声下的波形设计问题,还研究了一种恒包络MIMO波形设计方法。该方法利用了MIMO雷达具有多发射自由度的特性,进一步提高了输出的SNR。5.提出了阵元位置误差影响下的认知发射方向图设计方法。当阵列流形存在误差时,利用该方法设计的方向图在目标方位具有最大发射增益,同时在一个或多个干扰方向上置零,达到抑制干扰的效果。在此基础上,还研究了认知空时发射方向图设计方法。与传统发射方向图相比,认知空时发射方向图能显著提高输出的SCNR,并且能有效减小回波中杂波能量,降低对接收机动态范围的要求以及简化接收端的信号处理结构。
[Abstract]:Waveform design is a key problem in the research field of MIMO radar. The quality of the waveform design directly affects its performance. According to the different tasks of the MIMO radar, the design of the targeted MIMO waveform can improve the performance of the radar. Therefore, it is of great significance and application value to study the theory and algorithm related to the design of the waveform of the MIMO radar. At the same time, as a new hot spot in the field of radar research, cognitive radar has a great potential to improve radar performance because of its unique "receive and transmit" closed loop structure, and the waveform design is an essential link to highlight the cognitive characteristics of radar system. At present, how to design the waveform to improve the cognitive radar The ability to suppress interference is also concerned by more and more scholars. Aiming at the problem of MIMO radar orthogonal phase coded signal design, genetic algorithm and simulated annealing algorithm are the optimal design methods to improve the performance of autocorrelation and cross correlation. However, different application backgrounds have put forward specific requirements for the waveform setting. On the basis of the peak value of the correlation sidelobe and the low cross correlation peak, the waveforms must be studied with strict orthogonality and two specific conditions with zero correlation area. At present, the research results of the cognitive radar waveform are mainly concentrated in arbitrary waveform, because the envelopes of these arbitrary waveforms are not constant, so it is impossible to make full use of the thunder. In order to improve the efficiency of the transmitter, this paper studies the design of the constant envelope waveform design of cognitive radar in order to improve the performance of radar (such as target detection probability). This paper mainly studies some key technical problems in the design of MIMO radar orthogonal phase coding and the design of the constant envelope waveform of cognitive radar. Useful conclusions and achievements. The main research work and innovation in this paper are as follows: 1. an orthogonal binary phase code optimization design method based on Hadamard matrix is proposed. Using the orthogonal characteristics of the Hadamard matrix, the designed phase coded signal not only has lower autocorrelation side lobe peak value and cross correlation peak value, but also is strict between the 22 signals. Lattice orthogonality is helpful to improve the precision of radar target measurement and the effect of clutter cancellation. This method can optimize the long phase encoding only with small computer storage space. Therefore,.2. can be used in the design of the radar super long phase coding sequence, which is based on the zero correlation orthogonal phase based on the sequence two programming (SQP) algorithm. The optimization design method of bit coding is designed to directly determine the problem that the target detection performance of MIMO radar is the integrated pulse side lobe level of the output of the receiving beam after the beam formation. The fuzzy function sidelobe characteristic of the transmitted signal and ("and the signal") is introduced into the target function, and the phase code obtained by this method is used in the zero correlation area. The domain not only has ultra low autocorrelation sidelobe peaks and cross correlation peaks, but also has high principal to side ratio and excellent Doppler tolerance.3. to study the clutter characteristics of airborne MIMO radar under the influence of waveform sidelobe. Modeling of airborne MIMO radar clutter echo under the influence of waveform sidelobe and theoretical analysis The formula derives the influence of autocorrelation sidelobe and cross correlation on the clutter rank of airborne MIMO radar. In the application background of airborne MIMO radar, the autocorrelation sidelobe and cross correlation of the transmitted waveform can make the clutter rank increase obviously..4. is used to maximize the signal matching filter for the recognition of the cognitive radar waveform. The output terminal signal to noise ratio (SNR) and signal to clutter ratio (SCNR) are designed. The design method of constant envelope waveform under the color noise and the clutter is studied. The method is designed to optimize the ESD as the optimal approximation of the energy spectral density (ESD) of the optimized signal in the sense of the minimum mean square error. The SQP algorithm is used to optimize the phase coded signal. Compared with the traditional transmission signal such as linear frequency modulation signal (LFM), the phase coded signal designed by this method can effectively improve the output SNR or SCNR.. In view of the design of the waveform under the color noise, a design method of the constant envelope MIMO waveform is also studied. This method takes advantage of the characteristics of the MIMO radar with multiple emission degrees of freedom. The design method of cognitive emission pattern design under the influence of array element position error is proposed. When there is error in the array manifold, the pattern designed by this method has the maximum emission gain at the target orientation and zero in one or more interference directions, and the effect of interference suppression is achieved on the basis of this method. The cognitive space-time emission pattern design method is also studied. Compared with the traditional emission pattern, the cognitive space-time emission pattern can significantly improve the output SCNR, and can effectively reduce the clutter energy in the echo, reduce the dynamic range of the receiver and simplify the signal processing structure of the receiver.
【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN958
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本文编号：2062525