【摘要】：目標(biāo)與雷達(dá)之間的相對(duì)微運(yùn)動(dòng)(如振動(dòng)、旋轉(zhuǎn)、翻滾和進(jìn)動(dòng)等)會(huì)對(duì)回波信號(hào)進(jìn)行調(diào)制,產(chǎn)生微多普勒效應(yīng)。對(duì)微動(dòng)目標(biāo)的微多普勒進(jìn)行提取重構(gòu)并加以測(cè)量可獲得目標(biāo)的微動(dòng)參數(shù)和結(jié)構(gòu)參數(shù),基于此的目標(biāo)檢測(cè)識(shí)別技術(shù)被認(rèn)為是雷達(dá)目標(biāo)精確檢測(cè)識(shí)別領(lǐng)域中有巨大發(fā)展前景的研究方向之一。針對(duì)彈道目標(biāo)微多普勒特征提取與重構(gòu)方法的主要研究成果如下:1.分析了微動(dòng)目標(biāo)的微多普勒調(diào)制效應(yīng)。針對(duì)窄帶和寬帶兩種信號(hào)形式,分別建立了目標(biāo)進(jìn)動(dòng)的雷達(dá)回波模型,研究了進(jìn)動(dòng)目標(biāo)微多普勒的調(diào)制特性,推導(dǎo)了微多普勒與進(jìn)動(dòng)參數(shù)和目標(biāo)結(jié)構(gòu)參數(shù)的定量表達(dá)式,最后對(duì)比分析了微多普勒特征提取常用的時(shí)頻分析工具,對(duì)微動(dòng)目標(biāo)特征的提取重構(gòu)和參數(shù)估計(jì)具有重要的理論研究意義。2.在窄帶信號(hào)情況下提出了基于短時(shí)迭代自適應(yīng)-逆Radon變換(Short Time Iterative Adaptive Approach-Inverse Radon Transform,STIAA-IRT)的微多普勒特征提取與參數(shù)估計(jì)方法。首先針對(duì)短觀測(cè)時(shí)間常用時(shí)頻分析方法分辨力不足,難以區(qū)分頻率交疊嚴(yán)重且成分接近分量的問題,采用基于短時(shí)迭代自適應(yīng)(Short Time Iterative Adaptive Approach,STIAA)的時(shí)頻分析方法對(duì)目標(biāo)散射點(diǎn)模型進(jìn)行微多普勒特性提取。然后針對(duì)多分量微多普勒信號(hào)難以一一提取瞬時(shí)頻率以及信噪比較低的問題,利用逆Radon變換(Inverse Radon Transform,IRT)分離重構(gòu)不同散射點(diǎn)的微多普勒分量。該方法在低信噪比情況下能獲得多分量信號(hào)的完整微多普勒信息,為低信噪比、鄰近時(shí)頻分布情況下的微動(dòng)特征分離重構(gòu)和參數(shù)估計(jì)提供了有效途徑,最后利用仿真實(shí)驗(yàn)驗(yàn)證了所提方法具有優(yōu)于短時(shí)傅里葉變換和S方法的分辨能力和重構(gòu)性能。3.在寬帶信號(hào)情況下進(jìn)一步提出了基于逆Radon變換(IRT)的參數(shù)域微多普勒聚焦融合估計(jì)方法。首先針對(duì)寬帶信號(hào)微動(dòng)跨越距離單元的問題,采用子帶劃分的方法,將各子帶的窄帶信號(hào)分別利用STIAA時(shí)頻分析方法得到微多普勒時(shí)頻譜。然后針對(duì)各子帶間存在多普勒色散的問題,研究了對(duì)時(shí)頻圖進(jìn)行IRT后的參數(shù)空間實(shí)施變換以實(shí)現(xiàn)不同子帶的微多普勒聚焦融合的方法。該方法在低信噪比情況下能獲得寬帶目標(biāo)各散射點(diǎn)的高分辨微多普勒信號(hào),提高了參數(shù)的估計(jì)精度,最后利用仿真實(shí)驗(yàn)驗(yàn)證了所提方法的有效性。
[Abstract]:The relative micro-motion between target and radar (such as vibration, rotation, roll and precession) will modulate the echo signal and produce micro-Doppler effect. The micro-Doppler of the fretting target is extracted and reconstructed, and the fretting parameters and structure parameters of the target are obtained. The technology of target detection and recognition based on this is considered to be one of the promising research directions in the field of accurate detection and recognition of radar targets. The main research results of micro-Doppler feature extraction and reconstruction for ballistic targets are as follows: 1. The micro-Doppler modulation effect of fretting target is analyzed. The radar echo models of target precession are established for narrowband and wideband signals respectively. The modulation characteristics of micro-Doppler of precession target are studied. The quantitative expressions of micro-Doppler parameters, precession parameters and target structure parameters are derived. Finally, the time-frequency analysis tools commonly used in micro-Doppler feature extraction are compared and analyzed, which has important theoretical significance for feature extraction and parameter estimation of fretting target. A method for feature extraction and parameter estimation of microDoppler based on (Short Time Iterative Adaptive Approach-Inverse Radon transform STIAA-IRT is proposed for narrowband signals. First of all, due to the lack of resolution of time-frequency analysis methods commonly used in short observation time, it is difficult to distinguish the overlapping frequencies and the components close to the components. The time-frequency analysis method based on short-time iterative adaptive (Short Time Iterative Adaptive Approach-STIAA) is used to extract the micro-Doppler characteristics of the scattering point model of the target. Then, it is difficult to extract the instantaneous frequency and low SNR from multi-component microDoppler signals. The inverse Radon transform (Inverse Radon transform is used to separate and reconstruct the micro-Doppler components of different scattering points. This method can obtain the complete micro-Doppler information of multi-component signal under low SNR, which provides an effective way for fretting feature separation reconstruction and parameter estimation under low signal-to-noise ratio and adjacent time-frequency distribution. Finally, the simulation results show that the proposed method has better resolution and reconstruction performance than the STFT and S-method. In the case of wideband signal, a parameter domain micro-Doppler focusing fusion estimation method based on inverse Radon transform (IRT) is proposed. Firstly, aiming at the problem of wideband signal fretting span distance unit, the sub-band division method is used to obtain the micro-Doppler time-frequency spectrum by using the STIAA time-frequency analysis method for each sub-band narrowband signal. Then, aiming at the problem of Doppler dispersion among the sub-bands, the method of implementing the parameter space transformation of time-frequency map after IRT to realize the micro-Doppler focusing fusion of different sub-bands is studied. In the case of low SNR, the proposed method can obtain high-resolution micro-Doppler signals from each scattering point of a wideband target and improve the precision of parameter estimation. Finally, the effectiveness of the proposed method is verified by simulation experiments.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN957.51

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 高紅衛(wèi);謝良貴;文樹梁;匡勇;;微多普勒的一些工程問題研究[J];系統(tǒng)工程與電子技術(shù);2008年11期

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