【摘要】：電子對抗中,對截獲的雷達(dá)信號進(jìn)行處理是電子智能的一個重要領(lǐng)域。隨著電磁環(huán)境的日益復(fù)雜,低截獲概率(Low Probability of Interception,LPI)雷達(dá)發(fā)展迅速。為有效地對敵方LPI雷達(dá)進(jìn)行偵察和干擾,首先需要對截獲的雷達(dá)信號進(jìn)行分析。因此,低截獲概率雷達(dá)信號處理的理論和算法研究顯得日益迫切。本文在總結(jié)前人工作的基礎(chǔ)上,對典型的LPI雷達(dá)信號處理中的若干問題進(jìn)行了研究,主要內(nèi)容如下:1.介紹了LPI雷達(dá)的相關(guān)理論和影響截獲概率的各因素,總結(jié)了LPI雷達(dá)信號處理的研究現(xiàn)狀;2.研究了低信噪比條件下,基于分?jǐn)?shù)階Fourier變換的LFM(Linear Frequency Modulation,LFM)信號參數(shù)估計。本文提出了兩種插值算法彌補搜索步長和參數(shù)離散化的“柵欄效應(yīng)”帶來的缺陷,有效地提高了低信噪比條件下LFM信號參數(shù)估計的精度,并在此基礎(chǔ)了提出了迭代插值算法,使參數(shù)估計精度十分接近CRLB(Cramer-Rao Lower Bound,CRLB)。3.研究了三種典型復(fù)雜/復(fù)合調(diào)制雷達(dá)信號的識別算法:LFM/BPSK(Linear Frequecy Modulation and Binary Phase Shift Keying,LFM/BPSK)復(fù)合調(diào)制信號、FSK/BPSK(Frequency Shift Keying and Binary Phase Shift Keying,FSK/BPSK)復(fù)合調(diào)制信號和S型非線性調(diào)頻(Non-linear Frequency Modulation,NLFM)信號。通過對信號的相位和瞬時頻率進(jìn)行特征分析,采用二叉樹方法對上述三種復(fù)雜/復(fù)合調(diào)制雷達(dá)信號進(jìn)行了識別分析,并研究了Neyman-Pearson準(zhǔn)則下識別門限的選取以及門限對識別概率的影響。4.在實現(xiàn)復(fù)雜/復(fù)合調(diào)制雷達(dá)信號識別的基礎(chǔ)上,研究了其多參數(shù)估計算法。針對復(fù)合調(diào)制雷達(dá)信號:LFM/BPSK復(fù)合調(diào)制信號和FSK/BPSK復(fù)合調(diào)制信號,本文采用調(diào)制方式分離的方法,首先對信號的相位函數(shù)進(jìn)行乘2處理以去除二相編碼信息,以分別得到LFM信號和FSK信號進(jìn)行參數(shù)估計;然后在此基礎(chǔ)上分離出BPSK編碼信號部分,并采用小波法進(jìn)行解碼。針對S型NLFM信號,主要探討了其帶寬和中心頻率的估計方法。5.本文還提出了一種改進(jìn)型的分段濾波算法用于寬帶信號的降噪。通過對信號分段、頻移和頻域加窗實現(xiàn)寬帶信號的頻域濾波降噪,算法過程的核心運算為FFT運算,因此易于工程實現(xiàn)。
[Abstract]:In electronic countermeasures, the processing of intercepted radar signals is an important field of electronic intelligence. With the increasing complexity of electromagnetic environment, low probability of interception (Low Probability of Interception,LPI) radar has developed rapidly. In order to effectively detect and interfere with enemy LPI radar, it is necessary to analyze the intercepted radar signal. Therefore, the research on the theory and algorithm of low probability of interception radar signal processing is becoming more and more urgent. On the basis of summing up the previous work, this paper studies some problems in typical LPI radar signal processing, the main contents are as follows: 1. This paper introduces the related theory of LPI radar and the factors that affect the probability of interception, and summarizes the research status of LPI radar signal processing. 2. The parameter estimation of LFM (Linear Frequency Modulation,LFM signal based on fractional Fourier transform under the condition of low signal-to-noise ratio (SNR) is studied. In this paper, two interpolation algorithms are proposed to make up for the "fence effect" caused by the discretization of search step size and parameters, and the accuracy of parameter estimation of LFM signal is effectively improved under the condition of low signal-to-noise ratio (SNR). On this basis, an iterative interpolation algorithm is proposed. The accuracy of parameter estimation is very close to that of CRLB (Cramer-Rao Lower Bound,CRLB). 3. Three typical recognition algorithms of complex / composite modulation radar signals are studied: LFM/BPSK (Linear Frequecy Modulation and Binary Phase Shift Keying,LFM/BPSK) composite modulation signals, FSK/BPSK (Frequency Shift Keying and Binary Phase Shift Keying, FSK/BPSK) composite modulation signal and S-type nonlinear frequency modulation (Non-linear Frequency Modulation,NLFM) signal. Based on the analysis of the phase and instantaneous frequency of the signal, the binary tree method is used to identify and analyze the above three kinds of complex / composite modulation radar signals. The selection of recognition threshold under Neyman-Pearson criterion and the influence of threshold on recognition probability are studied. 4. On the basis of realizing the signal recognition of complex / composite modulation radar, the multi-parameter estimation algorithm is studied. Aiming at the composite modulation radar signal: LFM/BPSK composite modulation signal and FSK/BPSK composite modulation signal, this paper adopts the method of modulation separation. Firstly, the phase function of the signal is multiplied by 2 to remove the two-phase coding information. The parameters of LFM signal and FSK signal are estimated respectively. On this basis, the BPSK encoded signal is separated and decoded by wavelet method. For S-type NLFM signal, the estimation method of bandwidth and center frequency is discussed. 5. In this paper, an improved piecewise filtering algorithm is also proposed to reduce the noise of broadband signals. The frequency domain filtering and noise reduction of broadband signal is realized by dividing the signal, frequency shift and windowing in frequency domain. The core operation of the algorithm is FFT operation, so it is easy to be realized in engineering.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TN957.51

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 杜東平,唐斌;基于FrFT和子空間正交的LFM信號參數(shù)估計[J];電子科技大學(xué)學(xué)報;2004年03期

2 RKRayit,HKMardia,都書君;用自適應(yīng)前端檢測LPI雷達(dá)[J];電子對抗技術(shù);1995年05期

3 趙興浩;陶然;鄧兵;王越;;分?jǐn)?shù)階傅里葉變換的快速計算新方法[J];電子學(xué)報;2007年06期

4 周良臣;楊建宇;唐斌;;一種高效的LFM信號參數(shù)估計方法及性能分析[J];電子學(xué)報;2007年06期

5 熊剛;楊小牛;趙惠昌;;基于平滑偽Wigner分布的偽碼與線性調(diào)頻復(fù)合偵察信號參數(shù)估計[J];電子與信息學(xué)報;2008年09期

6 謝良聘,朱德恒;FFT頻域分析算法抑制窄帶干擾的研究[J];高電壓技術(shù);2000年04期

7 向崇文;黃宇;王澤眾;劉鋒;;基于FrFT的線性調(diào)頻-偽碼調(diào)相復(fù)合調(diào)制雷達(dá)信號截獲與特征提取[J];電訊技術(shù);2012年09期

8 朱健東;馬越;趙擁軍;;基于FRFT和累加積分的PRBC-LFM連續(xù)波信號參數(shù)估計[J];彈箭與制導(dǎo)學(xué)報;2013年05期

9 薛妍妍;劉渝;;LFM-BPSK復(fù)合調(diào)制信號識別和參數(shù)估計[J];航天電子對抗;2012年01期

10 ;CLASSIFICATION OF MPSK SIGNALS USING CUMULANT INVARIANTS[J];Journal of Electronics(China);2002年01期

相關(guān)博士學(xué)位論文 前1條

1 胥嘉佳;電子偵察信號處理關(guān)鍵算法和欠采樣寬帶數(shù)字接收機研究[D];南京航空航天大學(xué);2010年

相關(guān)碩士學(xué)位論文 前2條

1 趙鋒;基于相位展開的雷達(dá)信號調(diào)制方式識別算法研究[D];南京航空航天大學(xué);2011年

2 雷雪梅;低截獲概率信號識別與參數(shù)估計研究[D];電子科技大學(xué);2010年

，

本文編號：2495344