【摘要】：陣列單通道相對(duì)于陣列多通道具有體積小、造價(jià)低以及系統(tǒng)復(fù)雜度低等優(yōu)點(diǎn)。開(kāi)展陣列單通道高精度空間譜估計(jì)技術(shù)研究對(duì)于測(cè)向系統(tǒng)的小型化應(yīng)用具有重要意義。本文從陣列單通道的頻域和時(shí)域模型入手,針對(duì)信號(hào)波達(dá)方向(Direction of Arrival,DOA)時(shí)不變和時(shí)變的情形,對(duì)信號(hào)DOA估計(jì)和跟蹤問(wèn)題進(jìn)行了研究。本文的主要工作及成果如下:1.構(gòu)建了陣列單通道的頻域和時(shí)域空間譜估計(jì)模型。首先,在輪流采樣結(jié)構(gòu)下,將無(wú)限次輪巡得到的接收數(shù)據(jù)看作一個(gè)隨機(jī)過(guò)程,一次輪巡得到的數(shù)據(jù)視為隨機(jī)過(guò)程的一次實(shí)現(xiàn)(即樣本函數(shù)),通過(guò)相位補(bǔ)償建立了針對(duì)遠(yuǎn)場(chǎng)窄帶信號(hào)的頻域模型;然后利用信號(hào)在陣元間的延時(shí)不受其帶寬影響這一特性,基于帶通采樣與重構(gòu)定理,構(gòu)建了延時(shí)補(bǔ)償下的陣列單通道時(shí)域空間譜估計(jì)模型,使得寬、窄帶信號(hào)可以統(tǒng)一到同一模型下處理。2.針對(duì)非均勻高斯白噪聲背景,提出一種功率域最小二乘DOA估計(jì)器。首先推導(dǎo)了誤差功率的最小二乘表達(dá)式,然后以此為目標(biāo)函數(shù),采用模擬退火遺傳算法對(duì)其進(jìn)行搜索優(yōu)化,得到DOA估計(jì)值。模擬退火遺傳算法既繼承了遺傳算法全局把握能力好的優(yōu)勢(shì),又保留了模擬退火局部搜索能力強(qiáng)的特色,具有較高的搜索精度。此估計(jì)器給出了目標(biāo)函數(shù)的閉式表達(dá)式,避免了現(xiàn)有算法的迭代求解及其造成的誤差積累。并且由于表達(dá)式中不含與噪聲功率相關(guān)的參數(shù),因此所提估計(jì)器可以同時(shí)適用于均勻和非均勻高斯白噪聲。3.針對(duì)陣列單通道下寬帶信號(hào)DOA估計(jì)精度不高的問(wèn)題,提出貝葉斯最大后驗(yàn)概率估計(jì)方法實(shí)現(xiàn)了陣列單通道下的寬帶信號(hào)高精度DOA估計(jì)。首先推導(dǎo)了狀態(tài)向量的后驗(yàn)概率密度函數(shù),之后引入改進(jìn)的完美抽樣算法對(duì)其進(jìn)行優(yōu)化搜索,得到DOA估計(jì)值。由于狀態(tài)向量的后驗(yàn)概率密度中包含其先驗(yàn)信息,并且與估計(jì)量無(wú)關(guān)的參數(shù)是通過(guò)積分消去而不是估計(jì)值替代,所以此方法可以獲得較高的估計(jì)精度。4.對(duì)于信號(hào)方位緩慢變化的情形,將Cubature粒子濾波算法引入到陣列單通道DOA跟蹤中。算法對(duì)基本粒子濾波中重要性密度函數(shù)的構(gòu)造加以改進(jìn),將最新量測(cè)信息融入其中,使得從中抽取粒子的分布更加接近狀態(tài)的后驗(yàn)概率密度,從而提高了DOA跟蹤的精度。在遞推過(guò)程中,為了解決誤差協(xié)方差矩陣的對(duì)稱(chēng)性和正定性受到破壞而引起的數(shù)值不穩(wěn)定問(wèn)題,本文將平方根濾波與Cubature粒子濾波相結(jié)合,提出一種平方根Cubature粒子濾波(Square-root Cubature Particle,SCPF)算法,實(shí)現(xiàn)了陣列單通道下的高精度DOA跟蹤。此算法通過(guò)對(duì)誤差協(xié)方差陣取平方根保留了其對(duì)稱(chēng)性和正定性,并且減小了其條件數(shù),提高了數(shù)值計(jì)算的穩(wěn)定性。
[Abstract]:Single channel array has the advantages of small size, low cost and low complexity compared with multi-channel array. It is very important to study high-precision spatial spectrum estimation technology of single channel array for miniaturization of direction finding system. In the case of time-invariant and time-varying DOA, DOA estimation and tracking of signals are studied. The main work and achievements of this paper are as follows: 1. Estimation models of frequency-domain and time-domain spatial spectrum of array single channel are constructed. Firstly, the received data from infinite round trips are regarded as a random process, once, under the rotating sampling structure. The data obtained from the round trip is regarded as a random process (i.e. a sample function), and the frequency domain model of the far-field narrow-band signal is established by phase compensation. Then, based on the band-pass sampling and reconstruction theorem, the array single-channel time-space model with delay compensation is constructed by using the characteristic that the delay between the array elements is not affected by their bandwidth. In this paper, a power-domain least-squares DOA estimator is proposed for non-uniform Gaussian white noise background. Firstly, the least-squares expression of the error power is derived, and then the simulated annealing genetic algorithm is used to search and optimize the error power. The simulated annealing genetic algorithm (SAGA) inherits the advantage of good global grasp ability of GA and retains the characteristic of strong local search ability of SAGA, and has higher search precision. Moreover, the proposed estimator can be applied to both uniform and inhomogeneous white Gaussian noise due to the absence of noise power-dependent parameters in the expression. Degree DOA estimation. The posterior probability density function of the state vector is deduced firstly, and then an improved perfect sampling algorithm is introduced to optimize the search for DOA estimation. The Cubature particle filter algorithm is introduced into the array single channel DOA tracking in the case of slow signal azimuth change. The algorithm improves the structure of the importance density function in the basic particle filter, and incorporates the latest measurement information into it, so that the distribution of particles extracted from the array is better. In order to solve the problem of numerical instability caused by destroying the symmetry and positive definiteness of the error covariance matrix, a square-root Cubature particle filter (Square-Square-Square-Square-Square) is proposed by combining square-root filter with Cubature particle filter. The root Cubature Particle (SCPF) algorithm realizes high-precision DOA tracking in a single channel of the array. This algorithm preserves the symmetry and positive definiteness of the error covariance matrix by taking the square root, and reduces its condition number, thus improving the stability of the numerical calculation.
【學(xué)位授予單位】：解放軍信息工程大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TN911.23

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