本文關鍵詞： MIMO雷達 波形設計 混沌信號 脈沖壓縮 正交信號　出處：《吉林大學》2014年碩士論文　論文類型：學位論文

【摘要】：MIMO雷達作為一種新體制雷達，它打破了傳統(tǒng)雷達利用波束掃描的測探方式。MIMO通過發(fā)射正交波形的方式進行全空域覆蓋探測，具有更好的分辨率、抗截獲與抗干擾性等特點，成為近年來雷達領域研究的熱點。MIMO雷達發(fā)射信號的正交性直接影響MIMO雷達功能能否實現(xiàn)，因此正交波形設計是MIMO雷達技術中重要的一個環(huán)節(jié)。 目前MIMO雷達波形設計方法主要是通過建立代價函數(shù)，利用優(yōu)化算法進行組合優(yōu)化獲得正交編碼波形。這一類方法存在效率低、不能隨MIMO雷達陣元與發(fā)射信號碼長靈活變化等一類問題，本文研究將混沌信號應用到MIMO雷達波形設計中。混沌信號作為一類偽隨機信號，擁有良好的隨機性、初值敏感性、遍歷性、正交性等特點，本文充分發(fā)揮混沌信號的這一系列優(yōu)點進行MIMO雷達的正交波形設計。 本文針對MIMO雷達發(fā)射信號正交性的特點，利用混沌信號理論進行波形設計，主要研究工作如下： 1.首先，針對MIMO雷達發(fā)射信號的特點，本文對采用的MIMO雷達波形設計準則，即正交性準則與模糊特性準則進行了系統(tǒng)的闡述。 2.其次，本文采用混沌信號對高頻載波進行連續(xù)調幅的MIMO雷達波形設計方法。獲得的雷達信號的復包絡為仍為混沌信號，具有混沌信號的寬頻譜性、正交性等特點。雷達信號的性能主要由混沌信號決定，同時利用混沌信號初值敏感性，以及不同類型混沌信號的正交性，可以獲得大容量的正交信號集。 3.再次，本文采用基于混沌信號連續(xù)調頻的MIMO雷達波形設計方法。通過利用歸一化的混沌信號對載波信號的頻率進行連續(xù)調制，使得雷達信號的頻率在帶寬內隨機變化。本方法有別于基于混沌序列離散頻率編碼信號的波形設計，不需進行序列整數(shù)化和排序，而是使雷達信號的頻率完全按混沌信號的規(guī)律隨機變化，隨機性更佳�；诨煦缧盘栠B續(xù)調頻方法屬于對相位譜調制方法。利用該方法獲得的正交信號是具有非線性相位的脈沖壓縮信號，時寬帶寬積遠大于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編碼的MIMO雷達波形設計方法。利用混沌序列相位編碼波形設計方法代替常見偽隨機序列編碼波形，解決了因序列長度有限、得到自相關旁瓣過高的問題。同時，本文對基于混沌二相編碼的改進波形設計方法，，研究了基于雙混沌映射二相編碼波形設計方法。利用改進相位編碼方法獲得MIMO雷達發(fā)射信號在各發(fā)射周期發(fā)射不同一組正交波形，在保證MIMO雷達信號發(fā)射信號正交性的基礎上，進一步提高發(fā)射信號的隨機性，降低雷達信號被截獲的概率，提高雷達的隱身性。
[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.
【學位授予單位】：吉林大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN957.51

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