發(fā)布時間：2018-04-29 15:06

  本文選題：外輻射源雷達 + 數(shù)字電視信號�。� 參考：《北京理工大學(xué)》2014年博士論文

【摘要】：無線電頻譜是一種非常寶貴和有限的資源，隨著現(xiàn)代無線電應(yīng)用的高速發(fā)展，人們對頻譜資源的需求急劇增加，如何實現(xiàn)頻譜資源的高效共享成為世界各國的研究熱點。數(shù)字電視信號處于UHF頻段，適合寬帶無線通信應(yīng)用。其帶寬寬、發(fā)射功率穩(wěn)定、低空覆蓋良好等優(yōu)點使其成為一種較為理想的雷達輻射源。因此，數(shù)字電視信號非常適合于軍民共享的應(yīng)用。對基于數(shù)字電視信號的外輻射源雷達進行深入研究，可以為該頻段頻譜資源的充分利用和軍民共享提供理論依據(jù)和技術(shù)支撐。本課題在國家自然科學(xué)基金和國防基礎(chǔ)科研項目的支持下，深入分析了數(shù)字電視輻射源雷達干擾特點，重點研究了空、時域聯(lián)合的參考信號獲取及回波通道干擾抑制算法。研究成果對數(shù)字電視輻射源雷達的實際應(yīng)用具有一定的理論指導(dǎo)意義。本文主要研究內(nèi)容如下： 1、建立了數(shù)字電視輻射源雷達干擾和目標(biāo)回波模型。深入分析了參考通道干擾、天線頻率特性、分?jǐn)?shù)時延、回波天線轉(zhuǎn)動造成干擾非平穩(wěn)以及距離徙動和多普勒徙動對系統(tǒng)性能的影響。分析了自適應(yīng)對消和互模糊函數(shù)的運算量與信號帶寬的關(guān)系，指出數(shù)字電視信號帶寬寬造成運算量急劇增加，實時處理實現(xiàn)困難，需要研究運算效率高的自適應(yīng)對消算法和互模糊函數(shù)計算方法。通過以上分析，為參考信號獲取及回波通道干擾抑制算法的研究打下了基礎(chǔ)。 2、分析了參考通道干擾對系統(tǒng)對消增益和相參積累性能的影響，提出了空、時域聯(lián)合的參考信號獲取方法。對于較強的副瓣干擾采用基于寬零陷的數(shù)字波束形成方法抑制并獲取參考信號。提出了一種基于發(fā)射信號恢復(fù)的參考信號提純方法，對主瓣干擾和副瓣干擾殘余進行抑制。 3、分析了單純采用空域或時域方法抑制回波通道干擾的局限性，提出了空、時域聯(lián)合的回波通道干擾抑制方法。根據(jù)回波天線的不同工作狀態(tài)采用不同的空域干擾抑制方法，當(dāng)回波天線固定指向工作時，采用基于寬零陷的數(shù)字波束形成方法；當(dāng)回波天線轉(zhuǎn)動工作時，采用基于對角加載的SMI和自適應(yīng)零陷展寬方法。針對干擾的不同特點，提出了三種時域自適應(yīng)對消算法。（1）針對分?jǐn)?shù)時延影響及運算量大的問題，提出了將考慮分?jǐn)?shù)時延的LMS與快速塊LMS（fast block LMS algorithm，，F(xiàn)LMS）相結(jié)合的自適應(yīng)對消算法；（2）針對天線頻率特性不同造成的對消增益降低、回波天線轉(zhuǎn)動造成雜波非平穩(wěn)以及RLS算法運算量大的問題，提出了基于子帶分解的RLS和NLMS相結(jié)合的自適應(yīng)對消算法；（3）針對參考通道存在多徑干擾殘余的問題，提出了考慮參考通道存在多徑干擾及分?jǐn)?shù)時延影響的自適應(yīng)對消算法。提出了回波天線轉(zhuǎn)動工作時進一步提高積累增益的改進的波束聚焦方法。 4、分析了影響系統(tǒng)威力的主要因素。為解決數(shù)字電視信號互模糊函數(shù)運算量大的問題，采用基于脈壓的快速實現(xiàn)方法，該方法通過將信號分段并等效為脈沖信號，采用段內(nèi)脈壓和段間FFT實現(xiàn)相參積累。為解決長時間相參積累過程中目標(biāo)距離徙動和多普勒頻率徙動對積累增益的影響，采用基于keystone變換和分?jǐn)?shù)階傅里葉變換的徙動補償方法。提出了一種改進的基于CZT方法實現(xiàn)距離徙動補償?shù)幕ツ：瘮?shù)快速實現(xiàn)方法，與現(xiàn)有方法相比，在性能相當(dāng)?shù)那疤嵯�，運算量減小約50%。 分別通過實測數(shù)據(jù)驗證了上述所提算法的有效性，并給出了回波天線不同工作狀態(tài)下的綜合驗證結(jié)果。所提算法能夠有效抑制參考通道及回波通道干擾，提高對消增益和系統(tǒng)探測性能，并大大減小了實時處理的運算量。
[Abstract]:Radio spectrum is a very valuable and limited resource. With the rapid development of modern radio applications, the demand for spectrum resources is increasing rapidly. How to realize efficient sharing of spectrum resources has become a hot topic in the world. Digital TV signals are in the UHF band, suitable for broadband wireless communication applications. The advantages of power stability and low altitude coverage make it an ideal radar source. Therefore, the digital TV signal is very suitable for the application of military and civilian sharing. The in-depth study of the external radiant radar based on digital television signals can provide theoretical basis for the full utilization of the frequency spectrum resources and the sharing of military and civilian. Technical support. Under the support of National Natural Science Foundation and national defense research projects, this paper deeply analyzes the characteristics of digital TV radiant radar interference, and focuses on the study of the reference signal acquisition and echo channel interference suppression algorithm in the space and time domain. The practical application of the logarithmic type TV radiant radar is certain. The main contents of this paper are as follows:
1, the jamming and target echo model of digital television radiation source radar are established. The influence of the reference channel interference, the antenna frequency characteristic, the fractional delay, the interference nonstationary of the echo antenna rotation, the distance migration and the Doppler migration on the system performance are analyzed. The operation amount and the signal band of the adaptive cancellation and the cross ambiguity function are analyzed. With the wide relationship, it is pointed out that the bandwidth of the digital TV signal increases rapidly and the real-time processing is difficult. It is necessary to study the algorithm of adaptive cancellation and the calculation of the cross fuzzy function, which has high operational efficiency. Through the above analysis, it lays the foundation for the research of the reference signal acquisition and the echo channel interference suppression algorithm.
2, the influence of the reference channel interference on the gain and the coherent accumulation performance of the system is analyzed. A method of obtaining the reference signal in the space and time domain is proposed. For the strong sidelobe interference, a digital beamforming method based on the wide zero sink is used to suppress and obtain the reference signal. A reference signal based on the signal recovery is proposed to be purified. Methods the main lobe interference and sidelobe interference residual were suppressed.
3, the limitation of using space or time domain method to suppress echo channel interference is analyzed. The method of suppression of echo channel interference in space and time domain is proposed. Different air interference suppression methods are adopted according to the different working state of the echo antenna. When the echo antenna is fixed to the work, the digital beamforming based on wide zero sink is adopted. Methods: when the echo antenna rotates, we use diagonal loading based SMI and adaptive zero sink broadening method. In view of the different characteristics of the interference, three time domain adaptive cancellation algorithms are proposed. (1) for the problem of the influence of the fractional delay and the large amount of operation, the LMS and the fast block LMS (fast block LMS algorith) are proposed. M, FLMS) combined adaptive cancellation algorithm; (2) the adaptive cancellation algorithm based on subband decomposition of RLS and NLMS is proposed in view of the reduction of the cancellation gain caused by different antenna frequency characteristics, the non stationary clutter caused by the rotation of the echo antenna and the large computation of the RLS algorithm. (3) there is a multipath interference for the reference channel. In addition, the adaptive cancellation algorithm, which considers the presence of multipath interference and the effect of fractional delay in the reference channel, is proposed. An improved beam focusing method is proposed to further improve the accumulation gain when the echo antenna is rotated.
4, the main factors affecting the power of the system are analyzed. In order to solve the problem of the large amount of computation of the mutual fuzzy function of the digital TV signal, a fast realization method based on the pulse pressure is adopted. By segmenting the signal and equivalent to the pulse signal, this method uses the intra segment pulse pressure and the intersegment FFT to realize the coherent accumulation. The effect of distance migration and Doppler frequency migration on accumulation gain is based on the migration compensation method based on keystone transform and fractional Fu Liye transform. An improved method for realizing fast realization of distance migration compensation based on CZT method is proposed. Compared with the existing methods, the computational complexity is reduced on the premise of the equivalent performance. Small about 50%.
The effectiveness of the proposed algorithm is verified by the measured data, and the comprehensive verification results of the echo antenna in different working states are given. The proposed algorithm can effectively suppress the interference of the reference channel and echo channel, improve the performance of the cancellation gain and the system detection, and greatly reduce the computation of the real-time processing.

【學(xué)位授予單位】：北京理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TN949.197

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