本論文探討聲波於水下之應用。第一個部份為水下聲波成像，第二個部份為非線性負載結合水下聲波。第一部份主要是利用聲波掃描技術擷取更多的散射值資料，包括頻率掃描及角度掃描。然後利用Ewald球觀念填補於傳氏空間中，再利用二維線性內插法、校正和二維反傳氏轉換後，重建出物體的影像。在實驗中分別對一根鐵製圓柱體及兩根鐵製圓柱體成像。第二個部份為非線性負載應用於水下聲波。此部份利用非線性負載的特性，即會產生多個頻率分量訊號，用來偽裝欺敵。實驗以聲波為訊號源，發射單頻訊號，經過水下麥克風、放大器然後經過非線性負載，再經由麥克風把訊號傳到資料擷取卡。最後送回電腦做快速傅氏轉換，再分析諧頻聲波。此部份，以四種不同的非線性負載來做實驗。本研究對於水下成像、水下考古、非破壞性檢測及水下潛艦之電子戰等方面有一定的貢獻。

This paper discusses the application of acoustic waves in water. The first part is the underwater acoustic imaging, and the second part is the non-linear loads combining underwater acoustic waves. The first part acquires much more scattering data mainly by utilizing acoustic wave diversity techniques, including frequency diversity and angle diversity. Followed by adopting the concept of Ewald sphere to fill Fourier space, and then apply bi-linear interpolation, calibration and two-dimensional inverse Fourier transformation to reconstruct the image of objects. During the experiment, we image one metal cylinder and two metal cylinders respectively. The second part is about non-linear loads applied to underwater acoustic waves. This part applies the characteristics of non-linear loads that produce multiple frequencies component signal, which is used to disguise cheating. Experiment applies acoustic waves as the signal source to launch a base frequency signal passing the hydrophone and amplifier, and then transmit signal to data acquisition card through the non-linear loads. Lastly, send it back to the computer to perform fast Fourier transformation and then analyze harmonic acoustic waves. In this part, we experiment on the four different non-linear loads. This study has certain contribution in underwater acoustic imaging, underwater archeology, non-destructive testing and underwater submarine electronic warfare.

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