- 學位論文
東北海域水下通訊有限頻寬脈衝響應分析
Analysis of Band-Limited Impulse Response for Underwater Communication in Taiwan Northeastern Sea
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摘要
脈衝響應(Impulse Response)為描述通道特性的重要依據，脈衝響應定義為一脈衝訊號通過一特定系統後的響應，通常涵蓋所有頻率範圍。由於聲波頻率與應用範疇面的不同，本文討論有限頻寬之脈衝響應(Band-limited Impulse Response)。本研究於2009年8月於台灣東北海域北棉花峽谷進行脈衝響應時變性實驗，使用的聲源中心頻率為3.5kHz，頻寬80Hz屬窄頻聲源訊號。本實驗主要探討此淺水波導環境中，在相同的實驗測線下，接收點脈衝響應時變性。脈衝響應的分析方法主要利用自我回歸模式(Auto-Regressive, AR Model)做資料處理。由於實驗蒐集到的資料取樣頻率過大，本文在分析前先利用數位訊號處理理論，將取樣頻率降低至不失真的條件下，以求加快資料處理速度，並與聲源做相關性計算得到脈衝壓縮(Pulse Compression)，以提高訊號的可見度，最後將脈衝壓縮經由自我回歸模式，以得到聲傳的脈衝響應。本文主要探討定點的環境下聲傳的多路徑效益及通道脈衝響應的時變性，並加入應用於水下通訊的參數，量化脈衝響應計算該海域最大傳輸字元速率。
並列摘要
Impulse response is an important function describing characteristics of the channel. It is defined as the response of a pulse passing through a specific system with full bandwidth. In this thesis, we discuss the specific band-limited impulse response and time-variant, it’s using the acoustic data collected in an experiment of offshore Northeastern Taiwan in September 2009. The acoustic data are pulses centered at 3.5kHz with 80Hz bandwidth. This thesis studies the time-variant impulse responses in shallow water of the repeated acoustic tracks and their variation caused by oceanic environment. Auto-Regressive (AR) Model is used to analyze the impulse response. This thesis studies the time variant multiple-path and channel impulse response in a fixed point, and using RMS delay spread parameters to determine the maximum bit rate in communication field.
參考文獻
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