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寬帶信號(hào)DOA估計(jì)自回歸迭代算法
來源:電子技術(shù)應(yīng)用2012年第11期
張 飛1, 陳客松1, 唐 斌1, 吳宏剛2
1. 電子科技大學(xué) 電子工程學(xué)院,四川 成都 611731; 2. 中國(guó)民用航空局第二研究所,四川 成都 610041
摘要: 基于最小均方誤差(MMSE)準(zhǔn)則提出一種寬帶信號(hào)波達(dá)方向(DOA)估計(jì)算法。將寬帶信號(hào)通過窄帶濾波器組轉(zhuǎn)化為窄帶信號(hào),采用自回歸迭代方法恢復(fù)窄帶信號(hào)的稀疏表示,根據(jù)稀疏表示得到信號(hào)源個(gè)數(shù)和DOA估計(jì)。該算法不僅有超分辨率能力,而且不必預(yù)先知道信號(hào)源個(gè)數(shù)。此外,本算法能對(duì)相干信號(hào)源進(jìn)行DOA估計(jì)而不需要解相關(guān)預(yù)處理。仿真結(jié)果驗(yàn)證了該算法的有效性。
中圖分類號(hào): TN953.3
文獻(xiàn)標(biāo)識(shí)碼: A
文章編號(hào): 0258-7998(2012)11-0119-03
Wideband signal DOA estimation by using re-iterative algorithm
Zhang Fei1, Chen Kesong1, Tang Bin1, Wu Honggang2
1. School of Electronic Engineering, UESTC, Chengdu 611731, China; 2. The Second Research Institute of CAAC, Chengdu 610041, China
Abstract: This paper proposes a new algorithm, which is based on MMSE, for wideband signal spatial direction-of-arrival (DOA) estimation. Pass the wideband signal through a bank of narrowband filters to obtain narrowband signals, then recover the sparse representation of the narrowband signals by using re-iterative method, and estimate the number of the sources and DOA from the sparse representation. The new method not only has high resolution, but also do not require the number of sources for direction finding. Furthermore, this algorithm has the ability of estimating coherent signals without decorrelation processing. The simulated results confirmed the effectiveness of the new method.
Key words : reiterative; criterion of MMSE; sparse representation; DOA estimation

    寬帶信號(hào)DOA估計(jì)是陣列信號(hào)處理的一個(gè)重要分支,在目標(biāo)跟蹤、智能天線系統(tǒng)等方面有重要的應(yīng)用。目前寬帶信號(hào)DOA估計(jì)算法主要有兩大類:一類是非相干信號(hào)子空間法(ISM)[1],這類算法計(jì)算量大,分辨率低,且不能分辨相干信號(hào)源;另一類是相干信號(hào)子空間法(CSM)[2],這類算法分辨率高且能分辨相干信號(hào)源,但需要根據(jù)已知的預(yù)估計(jì)角度求解聚焦矩陣。

    近幾年提出的通過稀疏信號(hào)表示[3-4]進(jìn)行DOA估計(jì)的算法(FOCUSS[5],l1-SVD[6]等)不必求信號(hào)的自相關(guān)矩陣并對(duì)其進(jìn)行特征值分解,也不必預(yù)先估計(jì)信號(hào)源個(gè)數(shù),且不需要對(duì)相關(guān)信號(hào)進(jìn)行解相關(guān)預(yù)處理。本文基于MMSE準(zhǔn)則提出寬帶信號(hào)DOA估計(jì)自回歸迭代算法,通過恢復(fù)信號(hào)的稀疏表示實(shí)現(xiàn)超分辨率寬帶信號(hào)DOA估計(jì)。
1 信號(hào)模型
    寬帶信號(hào)的標(biāo)準(zhǔn)處理方法是將接收信號(hào)通過窄帶濾波器組得到不同頻率點(diǎn)的窄帶信號(hào)[3-5],再對(duì)其進(jìn)行后續(xù)處理。設(shè)有N個(gè)陣元的均勻直線陣列,相鄰陣元間距是入射信號(hào)最高頻率的半波長(zhǎng),遠(yuǎn)場(chǎng)寬帶信號(hào)從K (K≤N)個(gè)方向θ=[θ1,…,θK]到達(dá)陣列,通過D個(gè)中心頻率在寬帶信號(hào)頻率范圍內(nèi)的窄帶濾波器,得到D個(gè)不同頻率點(diǎn)的窄帶信號(hào),頻率點(diǎn)fd(1≤d≤D)處陣列單次快拍接收信號(hào)的表達(dá)式為:



 

 

間隔的增加,DOA個(gè)數(shù)估計(jì)在DOA間隔大于4°后收斂于真實(shí)值,DOA估計(jì)偏差在DOA間隔超過10°后為零。
    本文基于MMSE準(zhǔn)則提出一種寬帶信號(hào)DOA估計(jì)算法,采用自回歸迭代方法恢復(fù)信號(hào)的稀疏表示,估計(jì)出波達(dá)方向的信號(hào)幅度,由此同時(shí)得到信號(hào)源個(gè)數(shù)和波達(dá)方向估計(jì),省去了對(duì)信號(hào)自相關(guān)矩陣的特征值分解和對(duì)相干信號(hào)的去相關(guān)預(yù)處理,具有超分辨率能力。仿真驗(yàn)證了新算法的有效性,對(duì)實(shí)際工程中寬帶信號(hào)DOA估計(jì)的算法設(shè)計(jì)提供了有益的參考。
參考文獻(xiàn)
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[3] DONOHO D L,ELAD M,TEMLYAKVO V. Stable recovery of sparse overcomplete representations in the presence of noise[J]. IEEE Trans. Inf. Theory, 2006, 52(1):6-18.
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