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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/11067

Title: 高可靠度適應性水下通訊系統之研究---子計畫二:適應性方位估測應用於水中通訊系統之研 究(I)
The Study of Adaptive Direction-of-Arrival Estimation for Underwater Communications(I)
Authors: 張順雄;張麗娜
Contributors: NTOU:Department of Electrical Engineering
國立臺灣海洋大學:電機工程學系
Keywords: 水下通訊;方位估測;適應性束波器;多重路徑
Underwater communication;Direction-of-arrival estimator;Adaptive beamformer;Multi-path
Date: 1995-08
Issue Date: 2011-06-28T08:08:19Z
Publisher: 行政院國家科學委員會
Abstract: 摘要:隨著水下資源探測之需求日趨殷切,發展一 適合高速資料傳輸之水下通訊系統也就越重要 .而水下通訊中極待解決之問題為如何減緩因 多重路徑(multipath)問題所造成資料位元間之干擾(intersymbol interference).本整體型計畫中,將由 另一子計畫提出一適應性束波器來克服多路徑 干擾之問題;而本計畫主旨則在如何提供適應 性束波器所欲知道之訊號源方位,以便束波器 可利用訊號源之方向向量來區分訊號及干擾. 使用陣列天線來估測訊號源方位的問題,現今 已存在多種技術,其中以高析度之特徵結構法 最受重視,但通常這些方位估測法均假訊號源 模式為非同調(non-coherent)、遠場及窄頻之訊號,在此假設前題下,前述之高解析度法皆適用並 具極佳之解析能力.然而,這些假在水下環境中 即無法成立,由於訊號源在多重路徑傳播下會 產生同調(coherent)現象,而水下高速傳輸之訊號 為一寬頻訊號,且若訊號源距離無法遠大於陣 列之寬度時,將產生非常明顯的近場效應.故以 理想訊號源假設之方位估法來考量實際訊號, 其效能將變得不佳.本計畫將提出一方位估測 法,使其在水下通訊的環境下,針對其同調、近 場及寬頻之訊號源做出具實用性之適應性估測 .本計畫研究重點包括下列各項:1、在環境未變 動情形下,針對寬頻同調及近場之訊源模式提 出一方位估測法.在此部份之研究並不做適應 性方位估測.2、針對非理想訊號模式之方位估 測,提出一遞迴演算法則而作成可適應性方位估.3、以電腦模擬方式驗證此適應性方估測 法在實際水下通訊環境下之可行性.
Due to underwater multipath transmission, the signal source will encounter coherent phenomenon. In addition, broadband signal exists to maintain high speed transmission in underwater case. As a result, if the distance of signal source remained unable to far exceed the width of sensor array, a near field effect would become very obvious. Surely, the preliminary defined assumptions slapped on ideal signal source should not be taken into account. Of course, the theoretical exploration concerning far field (near field) narrow band, coherent (non-coherent) and far field (near field) wideband matters have exhaustively in depth be treated respectively, together with their computer simulations. In the successive section, the nature of wideband, coherent, near field (far field) signal source and the problems that could awake in their application on bearing estimation are also be analyzed. Consequently, the methods of far field approximation and coherent signal-subspace are being proposed to remedy the problems that practically come across by underwater signal transmission. This plan will discuss the theoretical matters, come up with several computer simulations to testify its capability. In practice, various experiments are also be carried out by receiving data in watertank to verify the accuracy and accessibility of the theory.
Relation: NSC85-2611-E019-010
URI: http://ntour.ntou.edu.tw/ir/handle/987654321/11067
Appears in Collections:[電機工程學系] 研究計畫

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