Estimation of the acoustic range of bat echolocation for extended targets
Estimation of the acoustic range of bat echolocation for extended targets
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DOI：
10.1121/1.4733537
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发表时间：
2012-09-01
影响因子：
2.4
通讯作者：
Schnitzler, Hans-Ulrich
中科院分区：
文献类型：
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作者：
Stilz, Wolfram-Peter;Schnitzler, Hans-Ulrich
在1到20米的距离内对蝙蝠环境的树木、草地和水面等扩展的自然结构进行超声，并使用移动超声声纳系统记录回声。通过对大气衰减的补偿，计算了每一距离反射回波的衍射衰减、目标的能量吸收衰减和双向几何扩展衰减。对于每种目标类型，补偿后的回声声压级衰减使用线性函数随距离拟合，得到反射损失和几何扩展的简单规律。再加上可变的大气衰减，就可以估计出从这些目标反射的信号在各种条件下的总体衰减。给定声纳系统的动态范围，就可以估计出声纳系统的最大探测距离。结果表明，最大范围主要受大气衰减的限制。反射表面的能量损失比几何扩散损失变化更大，这是超声目标之间差异的主要原因。根据大气条件、回声定位频率和声纳系统的动态范围，扩展背景（如森林边缘）的最大范围可短至2.4米。(C) 2012美国声学学会。[http://dx.doi.org/10.1121/1.4733537]
Extended natural structures of the bat environment such as trees, meadows, and water surfaces were ensonified in distances from 1 to 20 m and the echoes recorded using a mobile ultrasonic sonar system. By compensating the atmospheric attenuation, the attenuation of the reflected echo caused by diffraction, energy absorption of the target, and two-way-geometric spreading was calculated for each distance. For each target type the attenuation of the compensated echo sound pressure level was fitted over distance using a linear function which yields simple laws of reflection loss and geometric spreading. By adding to this function again variable atmospheric attenuation, the overall attenuation of a signal reflected from these targets can be estimated for various conditions. Given the dynamic range of a sonar system, the acoustic maximum detection distance can thus be estimated. The results show that the maximum range is dominantly limited by atmospheric attenuation. Energy loss in the reflecting surface is more variable than geometric spreading loss and accounts for most of the differences between the ensonified targets. Depending on atmospheric conditions, echolocation frequency, and the dynamic range of the sonar system, the maximum range for extended backgrounds such as a forest edge can be as short as 2.4 m. (C) 2012 Acoustical Society of America. [http://dx.doi.org/10.1121/1.4733537]