本文關(guān)鍵詞： 高速運(yùn)動(dòng)目標(biāo)一維成像 運(yùn)動(dòng)補(bǔ)償 分?jǐn)?shù)階傅里葉變換 Wigner-Hough變換 多項(xiàng)式相位變換　出處：《電子科技大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：一維距離像是目標(biāo)上各散射點(diǎn)回波在雷達(dá)距離向的矢量疊加所形成的幅度分布圖,可以反映出目標(biāo)精細(xì)的物理結(jié)構(gòu),是目標(biāo)識(shí)別的重要特征之一。由于目標(biāo)的一維距離像計(jì)算量較小、實(shí)時(shí)性高、并且有很好的穩(wěn)定性,因此有著重要的實(shí)用價(jià)值,在民用領(lǐng)域和軍用領(lǐng)域都有廣泛地應(yīng)用。但是,當(dāng)目標(biāo)高速運(yùn)動(dòng)時(shí),目標(biāo)的一維距離像會(huì)變模糊,出現(xiàn)譜峰分裂、頻譜展寬或畸變等現(xiàn)象。要得到目標(biāo)清晰地一維距離像,必須對(duì)目標(biāo)進(jìn)行運(yùn)動(dòng)補(bǔ)償以消除速度對(duì)成像的影響。本論文的主要研究?jī)?nèi)容如下:1.針對(duì)高速運(yùn)動(dòng)目標(biāo),研究了基于分?jǐn)?shù)階傅里葉變換(FrFT)的一維成像。LFM信號(hào)經(jīng)FrFT后,在某一特定的分?jǐn)?shù)階域有很好的時(shí)頻聚集性,表現(xiàn)為一峰值。本章采用了基于兩步峰值搜索的FrFT,首先使用大步長(zhǎng)搜索,估計(jì)出峰值的粗略值。然后進(jìn)行小步長(zhǎng)搜索,就可以得到峰值的精確值。最后根據(jù)峰值的位置信息就可以估計(jì)出LFM信號(hào)的參數(shù)。該方法有很高的參數(shù)估計(jì)精度,計(jì)算復(fù)雜度也比較小,并對(duì)噪聲有很好的魯棒性。并把該方法成功的應(yīng)用于對(duì)高速運(yùn)動(dòng)目標(biāo)的一維成像速度補(bǔ)償中,估計(jì)出的調(diào)頻率達(dá)到了很高的精度,取得了很好的成像效果。最后仿真驗(yàn)證了上述結(jié)論的正確性。2.研究了基于Wigner-Hough變換(WHT)的高速運(yùn)動(dòng)目標(biāo)一維成像。WHT是Wigner-Ville分布(WVD)和Hough變換(HT)的結(jié)合,是一種重要的時(shí)頻分析方法。LFM信號(hào)經(jīng)WVD后映射為WVD平面上的直線,再進(jìn)行Hough變換,即做直線的投影積分變換,會(huì)映射為WHT面上的峰值點(diǎn),根據(jù)峰值點(diǎn)的位置信息就可以實(shí)現(xiàn)對(duì)高速運(yùn)動(dòng)目標(biāo)一維距離像的速度補(bǔ)償。該方法能很好的抑制交叉項(xiàng)和噪聲的影響,有很高的參數(shù)估計(jì)精度,仿真實(shí)驗(yàn)取得了很好的一維成像效果。3.完成了基于離散多項(xiàng)式相位變換(DPT)的大加速度運(yùn)動(dòng)目標(biāo)的一維成像研究。大加速度目標(biāo)的回波可以看作是階數(shù)為3的多項(xiàng)式相位信號(hào)(PPS)。利用DPT實(shí)現(xiàn)了對(duì)PPS的二階項(xiàng)和三階項(xiàng)系數(shù)的估計(jì),求得的運(yùn)動(dòng)補(bǔ)償因子有效地消除了回波中高次項(xiàng)對(duì)成像的影響。DPT法有很高的參數(shù)估計(jì)精度,對(duì)運(yùn)動(dòng)補(bǔ)償后的信號(hào)做FFT可以得到目標(biāo)清晰地一維距離像,仿真驗(yàn)證了該方法的有效性。最后采用乘積型高階模糊函數(shù)法,解決了多分量PPS在PPT變換后的交叉項(xiàng)問(wèn)題。
[Abstract]:One-dimensional range is the amplitude distribution map formed by the vector superposition of each scattering point echo in the radar range direction on the target, which can reflect the fine physical structure of the target. It is one of the important features of target recognition. Because of the small computation of one-dimensional range profile, high real-time and good stability, it has important practical value. It is widely used in civil and military fields. However, when the target moves at high speed, the one-dimensional range profile of the target will become blurred and spectrum peak splitting will occur. It is necessary to obtain a clear one-dimensional range profile of the target, such as spectrum broadening or distortion. It is necessary to compensate the target motion to eliminate the influence of velocity on the imaging. The main contents of this thesis are as follows: 1. Aiming at the high speed moving target. In this paper, one dimensional imaging. LFM signal based on fractional Fourier transform (FrFT) is studied. After FrFT, it has good time-frequency aggregation in a specific fractional order domain. In this chapter, FrFT based on two-step peak search is used to estimate the rough value of peak value, and then small step size search is carried out. Finally, the parameters of LFM signal can be estimated according to the position information of the peak value. This method has high parameter estimation accuracy and low computational complexity. The method is successfully applied to compensate the velocity of one dimensional imaging of high speed moving target, and the estimated frequency has a high accuracy. Good imaging effect has been achieved. Finally, the correctness of the above conclusions is verified by simulation. 2. The research is based on Wigner-Hough transform. The high speed moving target imaging. WHT is a combination of Wigner-Ville distribution and Hough transform. LFM signal is mapped to a straight line on the WVD plane by WVD, and then Hough transform, that is, the projection integral transformation of a straight line. It can be mapped to the peak point on the WHT surface, and according to the position information of the peak point, the velocity compensation of the one-dimensional range profile of the high speed moving target can be realized. This method can suppress the influence of crossover term and noise. It has high precision of parameter estimation. Good one-dimensional imaging effect is achieved by simulation. 3. DPT-based discrete polynomial phase transformation is completed. The echo of a large acceleration target can be regarded as a polynomial phase signal of order 3 / PPS). The second and third order coefficients of PPS are estimated by using DPT. The obtained motion compensation factor effectively eliminates the effect of the high order term in the echo. DPT method has a high precision of parameter estimation. One dimensional range profile of the target can be clearly obtained by FFT, and the effectiveness of the method is verified by simulation. Finally, the product high-order fuzzy function method is adopted. The cross term problem of multicomponent PPS after PPT transform is solved.
【學(xué)位授予單位】：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)】：TN957.52

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本文編號(hào)：1444585