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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/28704

Title: 水下聲納偵測系統之設計
Authors: 洪賢昇;管明義
Contributors: NTOU:Department of Electrical Engineering
國立臺灣海洋大學:電機工程學系
Keywords: beamformer;blind adaptive;frequency estimation;detector;decision device
束波器;盲蔽適應性;頻率估計;偵測器;決策裝置
Date: 2004-12
Issue Date: 2011-10-21T02:39:25Z
Publisher: 2004全國電信研討會, 國立台灣海洋大學
Abstract: Abstract:In underwater environment, sonar is the most effective detection device at present. It uses propagation characteristics of acoustic wave to detect targets in the sea. The device at the front stage of sonar is a beamformer used to perform spatial filtering, attempting to suppress noise and eliminate interference. But conventional beamformers are very sensitive to the position error of the sensors, and need prior information about the direction of arrival (DOA) of the desired signal. To overcome the problems mentioned above, we adopt a blind adaptive beamformer as the device at the front stage of underwater sonar detection system.
When detecting submarine in underwater environment, acoustic sinusoidal signals generated by submarine propeller blade can be used for this task. But received signals are seriously distorted by the broadband noise from submarine engine and underwater environment, and multi-path channel effect. The information that we may have is the sinusoidal waves with unknown frequencies generated by propeller blades. Therefore, frequency estimation method is employed to estimate frequency and fed to a phase lock loop(PLL)to lock the desired frequency in order to suppress noise and eliminate interference. Next, the detector and the associated decision device are designed using statistical optimum decision theory. Finally, to evaluate the performance of the proposed underwater sonar detection system, computer simulations for Rayleigh fading channel are carried out.
摘要:在水下的環境中,聲納是目前最有效的水中偵測設備,它利用聲波在水中的傳播特性,對水中目標物進行偵測。在聲納的前端裝置是束波器,用來進行空間濾波,來抑制雜訊和消除干擾源。但傳統的束波器對於感測器擺設間距的誤差很敏感,且必須預先知道期望訊號的入射角度等等缺點,因而影響它的性能。因此本論文使用盲蔽適應性束波器來做為水下聲納偵測系統之前端裝置,來改善傳統束波器的缺點。
在水下環境偵測潛艦時,可利用潛艦螺旋槳葉片所產生的單頻弦波訊號來進行偵測。但因其訊號經過由潛艦引擎及水下環境產生的寬頻雜訊與多重路徑干擾的通道影響後,造成訊號嚴重衰減。我們所能掌握的資訊為頻率未知的單頻弦波訊號,因此結合弦波頻率估計的方法,估測弦波頻率後送至鎖相廻路來鎖定至正確頻率,以達到消除干擾和抑制雜訊的目的。其次再利用統計最佳決策理論來設計偵測器及決策裝置。最後我們利用電腦模擬結果來評估所提出的水下聲納偵測系統在萊里(Rayleigh)衰弱通道下的效能。
URI: http://ntour.ntou.edu.tw/handle/987654321/28704
Appears in Collections:[電機工程學系] 演講及研討會

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