【摘要】 将相干水声通信技术和混合码激励线形预测语音编码技术相结合进行了研究,设计并实现了一个可应用于浅海水声信道的实时数字语音通信系统。系统针对语音编码数据的特点,根据语音数据对恢复话音重要程度的不同,采用分层的信道编码以减少总体冗余度提高系统传输效率,采用鲁棒的语音帧同步机制、引入缓存机制保证语音数据流的连续性以提高系统整体性能;采用基于信道估计的内嵌二阶锁相环分数间隔判决反馈均衡器以对抗水声信道多径的影响。对该系统进行的海试在6km和11km距离上成功地实现了较高质量(可分辨出不同说话人)的实时水下语音通信,海试结果表明该系统可以应用于半双工实时水下数字语音通信。更多还原

【Abstract】 An underwater digital voice communication system aiming to be used in shallow-water acoustic channels was studied and implemented by combination of coherent underwater acoustic communication technique and MELP (Mixed Excitation Linear Prediction)digital voice encoding technique.According to different importance of voice data in recovering speech,this system used hierarchical channel encoding scheme to protect voice data in order to avoid introducing too many redundancies,trying to improve transferring efficiency of the whole system.To assure the time continuity of speech,which is of importance to the performance of whole system,a buffer-based mechanism and a robust voice data frame-synchronization scheme were used.A channel estimation based Decision Feedback Equalizer with fractionally-spaced feedforward filter(FS-DFE)and an embedded two-order Digital Phase-Locked Loops(DPLL)was used to account for multi-path effects of acoustic channels.A sea experiment was conducted and promising results were obtained:good quality(can identify different speakers)real-time underwater voice communications were successfully realized over 6km and 11 km.This result showed that this system can be applied to half-duplex real-time underwater digital voice communications.更多还原