本文選題：距離徙動 + 多普勒徙動��； 參考：《西安電子科技大學》2014年碩士論文

【摘要】：延長積累時間可增強目標的信號能量,進而改善雷達對目標的檢測性能。但對于高速、高機動目標而言,隨著時間的延長,雷達所接收到的目標回波會明顯地產生距離走動和彎曲以及多普勒頻偏、擴散和模糊等現象。對這類目標如果不能有效地消除距離徙動和多普勒徙動,那么其能量就得不到有效積累。本文主要針對天基雷達在對高機動微弱目標進行檢測的過程中的碰到的這些問題,介紹了幾種有效的長時間目標能量相參積累方法,并研究了在多目標環(huán)境下如何對不同目標的速度進行超分辨估計。首先,介紹了線性調頻信號及其脈沖壓縮原理,構建出高機動微弱目標的回波信號模型,并利用所建模型對目標作相對運動時所導致的距離徙動和多普勒徙動等問題進行了討論。接著,介紹了最大似然法,通過構造匹配函數和設計合適的多普勒調頻率搜索間隔和中心頻率搜索間隔可有效地消除距離徙動和多普勒徙動。分析了基于一階keystone變換的方法,它不需要目標的先驗信息就可一次性矯正多目標的距離徙動現象,但不能解決二次距離彎曲和多普勒頻率徙動問題。針對這個問題,介紹了基于二階keystone變換與匹配濾波相結合的方法,該方法可有效地解決目標做機動運動時導致能量擴散的問題,并且當目標回波發(fā)生多普勒模糊時也能夠很好地對其能量做出相參積累。其次,還介紹了一種基于二維頻域匹配濾波的方法,該方法是先將經過脈沖壓縮后的目標回波信號變換到距離-多普勒二維頻率域上,然后通過構造相應的補償函數進行匹配濾波處理。這種方法只需要對加速度進行一維的搜索估計,就能夠很好地消除因目標徑向速度所導致的距離走動和因目標徑向加速度所導致的距離彎曲和多普勒擴散等問題。最后,研究了一種基于子空間投影的多目標速度超分辨估計的方法,該方法首先對距離頻域-方位時域的數據進行一階Keystone變換,從而矯正目標信號的線性包絡走動,然后在距離時域和方位時域對目標所處的距離單元數據利用前后項空間平滑法進行解相參處理,接著對前后項空間平滑得到的相關矩陣進行特征分解,把分解得到的噪聲子空間向與目標速度有關的搜索導向矢量進行投影,最后再根據不同峰值對不同目標的速度進行超分辨估計。實驗仿真結果表明,本方法可對位于同一距離單元的多個目標對應的徑向速度進行有效的估計,從而提高天基雷達對徑向速度差異較小的多個目標的探測能力。
[Abstract]:Prolonging the accumulation time can enhance the signal energy of the target and improve the radar detection performance. However, for high speed and high maneuvering targets, with the extension of time, the radar echo will obviously produce the phenomena of range walking and bending, Doppler frequency offset, diffusion and blur. If the range migration and Doppler migration of these targets can not be eliminated effectively, the energy can not be effectively accumulated. In this paper, aiming at the problems encountered by space-based radar in the process of detecting high maneuvering weak targets, several effective methods of energy coherent accumulation for long time targets are introduced. And how to estimate the velocity of different targets in multi-target environment is studied. Firstly, the linear frequency modulation signal and its pulse compression principle are introduced, and the echo signal model of high maneuvering weak target is constructed. The range migration and Doppler migration caused by the relative motion of the target are discussed by using the established model. Then the maximum likelihood method is introduced. The range migration and Doppler migration can be effectively eliminated by constructing matching function and designing appropriate Doppler frequency search interval and center frequency search interval. The method based on first-order keystone transform is analyzed. It can correct the range migration phenomenon of multiple targets without prior information of target, but it can not solve the problem of secondary range bending and Doppler frequency migration. In order to solve this problem, a method based on second-order keystone transform and matched filter is introduced. This method can effectively solve the problem of energy diffusion caused by maneuvering motion of target. And when the target echo occurs Doppler ambiguity, it can also make coherent accumulation of its energy. Secondly, a method based on 2-D frequency domain matched filtering is introduced, in which the target echo signal after pulse compression is first converted to the range-Doppler 2-D frequency domain. Then the matching filter is processed by constructing the corresponding compensation function. This method only needs to estimate the acceleration in one dimension, and it can eliminate the range movement caused by the radial velocity of the target and the range bending and Doppler diffusion caused by the radial acceleration of the target. Finally, a multi-target velocity super-resolution estimation method based on subspace projection is studied. Firstly, the first order Keystone transform is applied to the range frequency-azimuth time domain data to correct the linear envelope walk of the target signal. Then in the time domain and azimuth time domain, the distance unit data of the target is solved by the spatial smoothing method of the front and rear terms, and then the correlation matrix obtained by the smoothing of the front and rear terms is decomposed by the characteristic. The decomposed noise subspace is projected to the search guidance vector related to the target velocity, and then the super-resolution estimation of the velocity of different target is carried out according to the different peak value. The experimental results show that the proposed method can effectively estimate the radial velocities of multiple targets located in the same range cell, thus improving the detection ability of space-based radar for multiple targets with little radial velocity difference.
【學位授予單位】：西安電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN957.51

【參考文獻】

相關期刊論文 前1條

1 游鴻;黃建國;金勇;徐貴民;;基于加權信號子空間投影的MUSIC改進算法[J];系統(tǒng)工程與電子技術;2008年05期

，

本文編號：1840017