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  本文關(guān)鍵詞： 高速弱目標(biāo) 長時間積累 Keystone變換 Radon-Fourier變換　出處：《哈爾濱工業(yè)大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：現(xiàn)代戰(zhàn)爭中，高速機動的低可探測目標(biāo)對雷達(dá)的探測能力提出了嚴(yán)峻的挑戰(zhàn)。信號的長時間積累是提高回波信噪比、改善雷達(dá)對高速運動弱目標(biāo)探測能力的有效途徑。針對脈沖多普勒雷達(dá)在凝視工作模式下，本文重點就目標(biāo)勻速直線運動和勻加速直線運動回波模型的建立，回波跨距離單元走動和多普勒擴展現(xiàn)象的分析以及目標(biāo)回波的長時間相參積累問題進行了研究。希望在未知目標(biāo)運動參數(shù)的情況下，改善目標(biāo)回波的積累效果，提高雷達(dá)對高速運動弱目標(biāo)的檢測性能。 在勻速直線運動目標(biāo)回波模型下，針對目標(biāo)跨距離單元走動的現(xiàn)象，分別介紹了基于Keystone變換和基于Radon-Fourier變換的長時間積累算法；提出了基于Radon變換的多普勒模糊因子估計方法，通過仿真實驗驗證了方法的有效性。根據(jù)仿真實驗得出結(jié)論：Keystone變換能夠在目標(biāo)運動參數(shù)未知的情況下實現(xiàn)包絡(luò)補償，但是在處理多目標(biāo)問題時將比較復(fù)雜。Radon-Fourier變換通過對目標(biāo)距離和速度的聯(lián)合搜索，能夠同時實現(xiàn)目標(biāo)運動軌跡的提取和回波能量的積累，避免了多普勒模糊因子估計的問題，，但是需要注意盲速旁瓣問題。 在勻加速直線運動目標(biāo)回波模型下，針對目標(biāo)的多普勒頻率擴展現(xiàn)象，提出了基于Keystone變換和二次相位補償?shù)乃惴�、基于二階Keystone變換聯(lián)合RFT處理的算法以及基于二階廣義Radon-Fourier變換的算法。針對多普勒調(diào)頻率估計問題，分別介紹了基于Dechirping、改進的Chirp-Fourier變換以及分?jǐn)?shù)階傅里葉變換的方法，通過仿真實驗驗證了方法的有效性。根據(jù)仿真實驗：基于Keystone變換的方法同樣無法避免多普勒模糊因子估計的問題，在多目標(biāo)情況下的應(yīng)用受到限制；基于二階Keystone變換聯(lián)合RFT處理的方法，適用于多目標(biāo)處理，但是在多普勒調(diào)頻率估計時對信噪比要求較高；基于二階廣義RFT的方法能夠通過目標(biāo)距離、速度、加速度的三維搜索實現(xiàn)目標(biāo)回波能量的相參積累，但是運算量較大，不適合工程實現(xiàn)。
[Abstract]:In modern warfare, the low detectable target with high speed maneuvering poses a severe challenge to radar detection ability. The long time accumulation of signal is to improve the signal to noise ratio (SNR) of echo. The effective way to improve the detection ability of radar to the weak target with high speed. In view of the staring mode of the pulsed Doppler radar, this paper focuses on the establishment of the echo model of the target with uniform linear motion and uniform acceleration linear motion. In this paper, the problem of echo traversing and Doppler spreading and the long time coherent accumulation of target echo are studied. It is hoped that the effect of target echo accumulation can be improved when the moving parameters of the target are unknown. The detection performance of radar for high speed moving weak target is improved. Under the echo model of the target with uniform velocity linear motion, the phenomenon of moving across the range unit of the target is studied. Long time accumulation algorithms based on Keystone transform and Radon-Fourier transform are introduced respectively. A Doppler fuzzy factor estimation method based on Radon transform is proposed. The effectiveness of the method is verified by simulation experiments. According to the simulation experiment, it is concluded that the envelope compensation can be realized when the moving parameters of the target are unknown. But when dealing with the multi-objective problem, it will be more complicated. Radon-Fourier transform can search the distance and velocity of the target through the joint search. It can simultaneously realize the extraction of target trajectory and the accumulation of echo energy, thus avoiding the problem of Doppler fuzzy factor estimation, but attention should be paid to the blind velocity sidelobe problem. Based on Keystone transform and quadratic phase compensation, an algorithm based on Keystone transform and quadratic phase compensation is proposed for the Doppler frequency spread phenomenon of the target with uniform acceleration linear moving target echo model. The algorithm based on the second order Keystone transform combined with RFT processing and the algorithm based on the second order generalized Radon-Fourier transform. The methods based on Dechirping, improved Chirp-Fourier transform and fractional Fourier transform are introduced respectively. The validity of the method is verified by simulation experiments. According to the simulation experiment, the method based on Keystone transform can not avoid the problem of Doppler fuzzy factor estimation. Applications in multi-objective situations are limited; The method based on second-order Keystone transform combined with RFT processing is suitable for multi-target processing, but the signal-to-noise ratio (SNR) is very high in Doppler frequency estimation. The method based on second-order generalized RFT can realize the coherent accumulation of target echo energy by 3D search of target distance, velocity and acceleration, but it is not suitable for engineering because of its large computation.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN957.51

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