數位多媒體資料著作權保護的重要性，隨著電腦的普及和電子資料交換便利性提升而與日俱增，而浮水印加密就是為了保護數位多媒體資料著作權而產生的技術。PN-Code是實現音訊浮水印加密的基礎，PN-Code具有極佳的對抗干擾特性和非常好的自相關性質，且碼技術實現容易，但其交互相關函數無法滿足展頻調變之條件，因此比較難以適用於多使用者的系統之中，所以本研究採用具有較低互相關特性的金氏碼 (Gold Code) 來產生音訊浮水印辨識碼。在本文中選擇金氏碼來取代PN-Code做為音訊浮水印的辨識碼，使音訊浮水印能夠實現多人存取的應用。其它的展頻編碼方法比較，實驗中發現金氏碼在某些配對上可能會造成浮水印解出成浮水印解出錯誤率的上升，未來研究也許可運用渦輪碼 (turbo code)，或是其他錯誤校正技術來改善此缺點，以期達到更佳的效果。 Due to the rapid growth of computer users and the convenience of digital data exchange, the importance of digital audio watermark has been increasing . The digital audio watermark is a technique used for intellectual property rights protection. PN-Code (pseudo-noise code) is a base for generating digital audio watermark. There are some advantages of PN-Code, such as robustness, high self-correlation and easy implementation, but it is difficult to be applied in the multiple-access communication system. The reason is that cross-correlation function of PN code is not satisfied with the requirement of spread spectrum. Therefore, Gold Code is applied to generate watermarking instead of PN-Code. According to the lower correlation of Gold Code, it can be used in the multiple-access communication system.In this study, it is also found that error rate of applying Gold Code in watermark extraction is higher than that of other methods while Gold Code in some case. This disadvantage could be overcome by some other error-correction methods in the future work.
