【摘要】：隨著陣列信號處理的日益發(fā)展,其在現代信號處理的地位也越加顯著,并在諸多領域,如:雷達、通信、射電天文以及醫(yī)學診斷等得到了廣泛應用。通過對傳感器陣列賦以不同的系數獲得最優(yōu)的輸出性能是自適應波束形成的目標,也是陣列信號處理的重要組成部分之一。寬帶信號帶寬足夠大能夠傳輸很大的信息量,并且混響背景相關性弱不容易受到信道傳輸過程的影響,在目標的檢測、參數估計和目標特征的提取這些方面上更具有優(yōu)勢,然而傳統(tǒng)的寬帶信號波束形成設計中會因為帶寬內子帶頻率的不同導致入射信號來波方向在波束主瓣寬度內的其他方向上時出現失真,在實際應用中無法滿足頻率上恒定束寬,這會導致算法性能的下降。因此,寬帶恒定束寬波束形成算法具有很大的實際意義。并且當期望寬帶信號和干擾信號共同在遠場平面入射時,如何抑制干擾信號和噪聲信號的影響也是恒定束寬波束形成中的一個重要問題。本文對恒定束寬波束形成算法的實現和波束圖中干擾方向上的零陷形成進行了深入研究。首先,在聚焦變換思路下把寬帶信號劃分后的不同頻率子帶上的數據通過聚焦變換矩陣聚焦到一個參考頻率上,推導了寬帶信號各個子帶頻域數據的輸出矩陣形式和RSS方法下的聚焦變換矩陣表達式,之后通過MVDR波束形成方法設計得到頻率不變恒定束寬并且具有很好零陷區(qū)域的波束形成器。其次,利用SRV約束實現恒定束寬最低旁瓣波束形成,然后在滿足期望信號指定來波方向上波束輸出增益最大和干擾信號來波方向零陷抑制的條件下,分析寬帶恒定束寬波束形成中最佳權矢量的設定,得出了滿足設計需求的SRV約束下恒定束寬MVDR最低旁瓣波束形成,并對其進行改進得到新算法,仿真證明改進后的方法在小采樣數和較高輸入SNR的情況下具有更好的輸出性能。再次,重點研究了最差環(huán)境下波束形成算法,詳細推導了波束形成算法的形成過程,引入橢球體約束集實現對任意方向向量失配的信號的無失真接收并將優(yōu)化問題化簡成為凸優(yōu)化問題,采用內點法求取最優(yōu)的權重向量。最后,將該波束形成算法用于寬帶恒定束寬波束形成算法中,提出了導向向量失配下恒定束寬波束形成算法,經過仿真研究,驗證了該算法對小采樣樣本引起的采樣自相關矩陣誤差以及方向向量失配都具有很好的魯棒性,并且可以實現帶寬上恒定束寬,在干擾信號來波方向上形成較大的零陷深度,波束形成系統(tǒng)有很好的輸出性能。
[Abstract]:With the development of array signal processing, its position in modern signal processing is becoming more and more prominent, and it has been widely used in many fields, such as radar, communication, radio astronomy and medical diagnosis. It is the target of adaptive beamforming to obtain the optimal output performance by assigning different coefficients to the sensor array, and it is also one of the important components of array signal processing. The broadband signal bandwidth is large enough to transmit a large amount of information, and the reverberation background correlation is not easily affected by the channel transmission process, so it has more advantages in target detection, parameter estimation and target feature extraction. However, in the traditional broadband signal beamforming design, due to the different subband frequency in the bandwidth, the incident signal will be distorted in other directions in the main lobe width of the beam, and the constant beam width in the frequency can not be satisfied in practical application, which will lead to the degradation of the performance of the algorithm. Therefore, the broadband constant beam width beamforming algorithm has great practical significance. When the broadband signal and the interference signal are expected to incident in the far field plane, how to suppress the influence of the interference signal and the noise signal is also an important problem in the constant beam width beamforming. In this paper, the realization of constant beam width beamforming algorithm and the zero notch formation in interference direction in beam graph are deeply studied. Firstly, under the idea of focusing transformation, the data on different frequency subbands of broadband signal are focused on a reference frequency by focusing transformation matrix, and the output matrix form of frequency domain data of each subband of broadband signal and the expression of focusing transformation matrix under RSS method are derived. then the beamformer with constant frequency beam width and good zero notch region is designed by MVDR beamforming method. Secondly, the constant beamwidth minimum sidelobe beamforming is realized by using SRV constraint, and then the optimal weight vector setting in broadband constant beamwidth beamforming is analyzed under the condition of satisfying the maximum output gain of the beam output and the zero notch suppression of the interference signal in the specified incoming direction of the desired signal, and the constant beamwidth MVDR minimum sidelobe beamforming under the SRV constraint to meet the design requirements is obtained, and a new algorithm is obtained. The simulation results show that the improved method has better output performance under the condition of small sampling number and high input SNR. Thirdly, the beamforming algorithm in the worst environment is studied, and the forming process of the beamforming algorithm is deduced in detail. The ellipsoid constraint set is introduced to realize the distortionless reception of the mismatched signal in any direction vector, and the optimization problem is simplified into a convex optimization problem. The optimal weight vector is obtained by the interior point method. Finally, the beamforming algorithm is applied to broadband constant beamwidth beamforming algorithm, and a constant beamwidth beamforming algorithm under guidance vector mismatch is proposed. The simulation results show that the algorithm has good robustness to the sampling autocorrelation matrix error and direction vector mismatch caused by small sampling samples, and can achieve constant beam width on bandwidth and form a large zero-notch depth in the wave side of the interference signal. Beamforming system has good output performance.
【學位授予單位】：哈爾濱工程大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN911.7

【引證文獻】

相關碩士學位論文 前1條

1 龐宇;語音分離技術的研究與實現[D];國防科學技術大學;2016年

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本文編號：2501186