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移动设备VOIP实时通信软件中的回声延迟估算方法 被引量:1
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作者 胡海 李晓鹏 +1 位作者 周平 王伟 《中国管理信息化》 2012年第10期81-83,共3页
在VIOP通信软件中有一个严重影响通话质量的因素就是回声。回声是指说话者通过通信设备发送给其他人的语音又重新又回到自己的听筒里的现象。回声会对说话者产生严重的干扰,必须想办法消除或削弱。一般,回声分为两种,即"电路回声&q... 在VIOP通信软件中有一个严重影响通话质量的因素就是回声。回声是指说话者通过通信设备发送给其他人的语音又重新又回到自己的听筒里的现象。回声会对说话者产生严重的干扰,必须想办法消除或削弱。一般,回声分为两种,即"电路回声"和"声学回声"。"电路回声"可以通过硬件设备的合理设计而消除。而"声学回声"由于其产生的环境复杂,不容易消除。本文通过分析移动设备的声卡的参数设定和录放音数据的时序关系,总结出一套估算该类设备上声学回声延迟的方法,有效地提高了回声消除的效率和效果,为该类设备上设计VOIP通信软件的回声消除模块提供了参考。 展开更多
关键词 回声 声学回声 回声延迟 回声消除器 采样率 重采样
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Characteristic Analysis of Underwater Acoustic Scattering Echoes in the Wavelet Transform Domain 被引量:1
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作者 Mei Yang Xiukun Li +1 位作者 Yang Yang Xiangxia Meng 《Journal of Marine Science and Application》 CSCD 2017年第1期93-101,共9页
Underwater acoustic scattering echoes have time–space structures and are aliasing in time and frequency domains. Different series of echoes properties are not identified when incident angle is unknown. This article i... Underwater acoustic scattering echoes have time–space structures and are aliasing in time and frequency domains. Different series of echoes properties are not identified when incident angle is unknown. This article investigates variations in target echoes of monostatic sonar to address this problem. The mother wavelet with similar structures has been proposed on the basis of preprocessing signal waveform using matched filter, and the theoretical expressions between delay factor and incident angle are derived in the wavelet domain. Analysis of simulation data and experimental results in free-field pool show that this method can effectively separate geometrical scattering components of target echoes. The time delay estimation obtained from geometrical echoes at a single angle is consistent with target geometrical features, which provides a basis for object recognition without angle information. The findings provide valuable insights for analyzing elastic scattering echoes in actual ocean environment. 展开更多
关键词 underwater acoustic scattering echoes geometrical scattering components time delay estimation wavelet transform
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