基于混沌信号的MIMO雷达波形设计方法研究

发布时间：2018-01-20 08:20

本文关键词： MIMO雷达波形设计混沌信号脉冲压缩正交信号　出处：《吉林大学》2014年硕士论文　论文类型：学位论文

【摘要】：MIMO雷达作为一种新体制雷达，它打破了传统雷达利用波束扫描的测探方式。MIMO通过发射正交波形的方式进行全空域覆盖探测，具有更好的分辨率、抗截获与抗干扰性等特点，成为近年来雷达领域研究的热点。MIMO雷达发射信号的正交性直接影响MIMO雷达功能能否实现，因此正交波形设计是MIMO雷达技术中重要的一个环节。目前MIMO雷达波形设计方法主要是通过建立代价函数，利用优化算法进行组合优化获得正交编码波形。这一类方法存在效率低、不能随MIMO雷达阵元与发射信号码长灵活变化等一类问题，本文研究将混沌信号应用到MIMO雷达波形设计中。混沌信号作为一类伪随机信号，拥有良好的随机性、初值敏感性、遍历性、正交性等特点，本文充分发挥混沌信号的这一系列优点进行MIMO雷达的正交波形设计。本文针对MIMO雷达发射信号正交性的特点，利用混沌信号理论进行波形设计，主要研究工作如下： 1.首先，针对MIMO雷达发射信号的特点，本文对采用的MIMO雷达波形设计准则，即正交性准则与模糊特性准则进行了系统的阐述。 2.其次，本文采用混沌信号对高频载波进行连续调幅的MIMO雷达波形设计方法。获得的雷达信号的复包络为仍为混沌信号，具有混沌信号的宽频谱性、正交性等特点。雷达信号的性能主要由混沌信号决定，同时利用混沌信号初值敏感性，以及不同类型混沌信号的正交性，可以获得大容量的正交信号集。 3.再次，本文采用基于混沌信号连续调频的MIMO雷达波形设计方法。通过利用归一化的混沌信号对载波信号的频率进行连续调制，使得雷达信号的频率在带宽内随机变化。本方法有别于基于混沌序列离散频率编码信号的波形设计，不需进行序列整数化和排序，而是使雷达信号的频率完全按混沌信号的规律随机变化，随机性更佳。基于混沌信号连续调频方法属于对相位谱调制方法。利用该方法获得的正交信号是具有非线性相位的脉冲压缩信号，时宽带宽积远大于1，具有良好的模糊特性。 4.最后，本文采用基于混沌序列相位编码的MIMO雷达波形设计方法。利用混沌序列相位编码波形设计方法代替常见伪随机序列编码波形，解决了因序列长度有限、得到自相关旁瓣过高的问题。同时，本文对基于混沌二相编码的改进波形设计方法，，研究了基于双混沌映射二相编码波形设计方法。利用改进相位编码方法获得MIMO雷达发射信号在各发射周期发射不同一组正交波形，在保证MIMO雷达信号发射信号正交性的基础上，进一步提高发射信号的随机性，降低雷达信号被截获的概率，提高雷达的隐身性。
[Abstract]:As a new system radar, MIMO radar has better resolution by transmitting orthogonal waveforms. The characteristics of anti-interception and anti-jamming have become a hot topic in the field of radar in recent years. The orthogonality of the transmitted signal of MIMO radar has a direct impact on the realization of MIMO radar function. Therefore, orthogonal waveform design is an important part of MIMO radar technology. At present, the MIMO radar waveform design method is mainly through the establishment of cost function, using optimization algorithm to optimize the combination of orthogonal coding waveform, this kind of method has low efficiency. The chaotic signal is applied to the design of MIMO radar waveform. The chaotic signal is regarded as a kind of pseudorandom signal. It has good randomness, initial value sensitivity, ergodicity, orthogonality and so on. This paper gives full play to this series of advantages of chaotic signal to design the orthogonal waveform of MIMO radar. According to the orthogonality of MIMO radar transmit signal, the waveform is designed by using chaotic signal theory. The main research work is as follows: 1. Firstly, according to the characteristics of MIMO radar signal, the design criteria of MIMO radar waveform, i.e. orthogonality criterion and fuzzy characteristic criterion, are systematically described in this paper. 2. Secondly, the MIMO radar waveform design method of chaotic signal is adopted. The complex envelope of the obtained radar signal is still chaotic signal, which has the wide spectrum of chaotic signal. The performance of radar signal is mainly determined by chaotic signal. By using the sensitivity of initial value of chaotic signal and the orthogonality of different types of chaotic signal, a large capacity orthogonal signal set can be obtained. 3. Thirdly, the MIMO radar waveform design method based on continuous frequency modulation of chaotic signal is adopted, and the frequency of carrier signal is modulated continuously by using the normalized chaotic signal. This method is different from the waveform design of discrete frequency coding signal based on chaotic sequence and does not need sequence integer and sorting. Instead, the frequency of radar signal is changed randomly according to the law of chaotic signal. The method based on continuous frequency modulation of chaotic signal belongs to the phase spectrum modulation method. The orthogonal signal obtained by this method is a pulse compression signal with nonlinear phase, and the time bandwidth wide product is far greater than 1. It has good fuzzy property. 4. Finally, the MIMO radar waveform design method based on chaotic sequence phase coding is adopted, and the chaotic sequence phase coding waveform design method is used to replace the common pseudorandom sequence coding waveform. The problem that the autocorrelation sidelobe is too high is solved because of the limited length of the sequence. At the same time, the improved waveform design method based on chaotic two-phase coding is proposed in this paper. The design method of two-phase coded waveform based on double chaotic mapping is studied. The improved phase coding method is used to obtain the different sets of orthogonal waveforms transmitted by MIMO radar signals in different transmission periods. On the basis of ensuring the orthogonality of MIMO radar signal, the randomness of transmitting signal is further improved, the probability of radar signal being intercepted is reduced, and the stealth of radar is improved.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN957.51

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