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首页> 外文会议>OCEANS 2016 MTS/IEEE Monterey >Real-time TDOA measurements of an underwater acoustic source
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Real-time TDOA measurements of an underwater acoustic source

机译：水下声学来源的实时TDOA测量

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The direction of arrival of sound waves has been extensively used for passive acoustic tracking of underwater sound sources, such as marine mammals or ultrasonic electronic tags attached to animals or submerged equipment. This process can be automated by measuring the time difference of arrival (TDOA) of the sound wave arriving to two or more hydrophones and then calculating the relative direction of the acoustic source using those time differences. Although the generalized cross-correlation between the received signals is a common technique for determining the TDOA, the underwater environment introduces several distortions in amplitude and phase of the received sound waves due to reflections and reverberation, particularly in confined spaces. This is aggravated by the variation of the sound propagation speed with temperature, pressure and salinity. Because of this, the use of the cross-correlation method not effective to determine the TDOA especially when using single frequency pulses as the transmitted signal. In this work we propose an alternative method to calculate the TDOA, consisting in the analysis of the initial part of the received signals to discover a series of similar zero-crossing periods to identify their beginning, and then calculating the time difference between them. We have implemented this technique in a reconfigurable system-on-chip, attaching to an embedded ARM processor a custom designed digital signal processing system. This has been tested in a test tank and in outside environment. This system is capable of computing in real-time the 2D direction of an underwater acoustic transmitter, and combining the different directions resulting from the relative movement between transmitter and receiver it is possible to estimate the relative position of the acoustic source.
机译：声波到达方向已经广泛用于水下声源的被动声学跟踪，例如附着在动物或浸没设备上的海洋哺乳动物或超声电子标签。通过测量到达两个或多个流水录的声波的到达（TDOA）的时间差，可以自动化该过程，然后使用那些时间差来计算声学源的相对方向。尽管接收信号之间的广义交叉相关是用于确定TDOA的常用技术，但是水下环境引起了由于反射和混响而引起接收声波的幅度和相位的若干失真，特别是在限制空间中。这是通过温度，压力和盐度的声音传播速度的变化而加剧。因此，使用互相关方法的使用无效地确定TDOA，特别是当使用单频脉冲作为发送信号时。在这项工作中，我们提出了一种替代方法来计算TDOA，该方法在分析接收信号的初始部分的分析中，以发现一系列类似的零交叉时段来识别它们的开始，然后计算它们之间的时间差。我们已经在可重新配置的片上实施了该技术，附着到嵌入式臂处理器是定制设计的数字信号处理系统。这已经在测试罐和外部环境中进行了测试。该系统能够在水下声发射器的2D方向上进行计算，并且组合由发射器和接收器之间的相对运动产生的不同方向，可以估计声源的相对位置。

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