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研究生：	徐書鴻 Hsu, Shu-Hung
論文名稱：	海面降雨水下環境噪音頻率特性 Frequency characteristics of underwater ambient noises caused by rainfalls
指導教授：	黃清哲 Huang, Ching-Jer
學位類別：	碩士 Master
系所名稱：	工學院 - 水利及海洋工程學系 Department of Hydraulic & Ocean Engineering
論文出版年：	2018
畢業學年度：	106
語文別：	中文
論文頁數：	64
中文關鍵詞：	水下降雨噪音、水聽器量測、資料浮標
外文關鍵詞：	Underwater rainfall noise, Hydrophone measurement, Data buoy
相關次數：	點閱：73 下載：1
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目前全台的雨量測站，皆是在陸域上，並無任何是位於海洋中。然而，海洋降雨是一項重要但又不易量測的環境參數，考慮到環境條件與陸地截然不同，儀器容易故障，而且也不易保養和維修。因此，發展出利用水中聲學的方式，透過聲學儀器在水下量測因雨滴所產生的噪音，進而推估出海上的降雨情況。本研究於南灣資料浮標 (Data Bouy) 下方水深約1 ~ 2公尺處掛載水聽器 (Hydrophone)，水下噪音的量測採用每60分鐘量測3分鐘的方式進行，取樣頻率為32 kHz。若是遇到颱風侵台期間，或是有出現暴雨的可能性，可以將工作週期縮短成每10分鐘，獲取更多的原始數據。量測到的原始數據以快速傅立葉轉換法 (FFT) 對於取樣訊號進行頻譜分析，以獲得水下噪音頻譜，利用第三代行動通訊技術即時回傳至陸地端。降雨資料選用海棠颱風侵台期間所帶來的豐沛雨量，在進行降雨量分析之前，需要了解平常日未下雨時的環境噪音特性，再將降雨資料進行比對，才具有其物理意義。環境噪音頻域訊號在頻率1 kHz以下的聲壓位準是與風速成正相關，說明了風速大小對於頻譜的影響。將降雨期間的頻域訊號對照相同風速區間的環境噪音，在頻率2 ~ 10 kHz的聲壓位準都有上升趨勢，其中以頻率2 ~ 6 kHz最為明顯，在低頻的部分，風浪的影響較顯著，不過當降雨強度過大時，聲壓位準會於全頻段皆抬升。未來若資料量足夠，除了可以由回傳的頻譜即時判斷當地降雨情形，也可以進行量化的計算，推估當地降雨量的經驗公式。

In this study, the noise generated by raindrops under water was measured using acoustic instruments in order to estimate the rainfall at sea. The hydrophone was mounted at a depth of approximately 2 meters below the data buoy in Nanwan; measurement of underwater noise was performed for three minutes every hour at a sampling frequency of 32 kHz. The measured raw data were subjected to spectrum analysis using the Fast Fourier Transform method for the sampled signals to obtain the underwater noise spectrum, and were immediately transmitted back to land by wireless communication. Rainfall data were selected from the abundant rainfall during the invasion by typhoon Haitang in Taiwan in 2017. Analysis of ambient noise in absence of rain for subtraction purposes indicated that the ambient noise frequency signal at a frequency less than 1 kHz was positively correlated with the wind speed. Comparing the frequency domain signal during rainfall with the ambient noise in the same wind speed range, there was an upward trend in the sound pressure level from 2 to 6 kHz. In the future, sufficient data may allow estimation of an empirical formula for the local rainfall

摘要............................ I
ABSTRACT....................... II 
誌謝..........................VIII
目錄............................IX
表目錄..........................XI
圖目錄.........................XII
符號...........................XVI
第一章 緒論.......................1
1-1 研究動機......................1
1-2 文獻回顧......................2
1-3 研究方法......................3
1-4 論文架構......................4
第二章 相關理論....................5
2-1 海洋環境噪音特性...............5
  2-1-1 研究簡史..................5
  2-1-2 海洋環境噪音組成...........6
  2-1-3 風浪噪音..................8
  2-1-4 降雨噪音..................9
2-2 聲壓與聲強計算................11
2-3 訊號處理方法..................13
  2-3-1 取樣定理.................13
  2-3-2 快速傅立葉轉換............15
第三章 實驗設置...................18
3-1 觀測系統架構..................18
3-2 風速量測設備介紹...............19
  3-2-1 風速計....................19
  3-2-2 風速資料擷取系統...........21
3-3 水下噪音量測設備介紹...........22
  3-3-1 水聽器....................22
  3-3-2 水下噪音訊號擷取系統.......26
  3-3-3 水下噪音訊號分析系統......28
3-4 電力及通訊系統................29
3-5 觀測流程.....................31
3-6 儀器安裝配置..................31
3-7 結語.........................33
第四章 實驗結果...................34
4-1 氣象資料.....................34
  4-1-1降雨資料..................34
  4-1-2風速資料..................39
4-2 水下環境噪音分析..............40
4-3 水下降雨噪音分析..............44
4-4 雷達回波圖....................53
4-5 結語.........................58
第五章 結論與建議.................59
5-1 結論.........................59
5-2 建議.........................60
參考文獻	62


                                    

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校內：2021-07-01公開
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