Zhang W P, Jen P H
Proc Natl Sci Counc Repub China B. 1984 Jul;8(3):222-8.
Utilizing a three-ramp platform, we studied the detection of a revolving and a stationary target in the presence of background clutter by trained Eptesicus fuscus. During the test, the mean amplitude of echo from either target was always larger than that of the background echoes at the bat-to-target distance of 30, 70 and 100 cm. The amplitude of the echo reflected back from a revolving target was modulated between a maximum and a minimum value. An electric motor was used to revolve a target. The frequency contents of the motor noise were mostly below 1 kHz. While the total percent response of approaching either target is always more than 90% at every bat-to-target distance tested, the bats approach a revolving target more frequently than a stationary one. Echolocation pulses emitted by the bats during the test were recorded and analyzed. The bats shortened their pulse durations and interpulse intervals and lowered the frequency contents as they entered into the crawling phase from the searching phase. Potential interference of background echoes and ambient noise with the performance of the bats is discussed. The preference of a revolving target to a stationary one by the bats is perhaps due to the fact that a revolving target has a higher releasing value than a stationary one does.
我们利用一个三斜坡平台，研究了受过训练的棕蝠在存在背景杂波的情况下对旋转目标和静止目标的探测。在测试过程中，在蝙蝠与目标距离为30厘米、70厘米和100厘米时，来自任一目标的回波平均幅度总是大于背景回波的幅度。从旋转目标反射回来的回波幅度在最大值和最小值之间调制。使用一个电动马达使目标旋转。马达噪声的频率成分大多低于1千赫。虽然在测试的每个蝙蝠与目标距离处，接近任一目标的总反应百分比总是超过90%，但蝙蝠接近旋转目标的频率比静止目标更高。记录并分析了测试期间蝙蝠发出的回声定位脉冲。当蝙蝠从搜索阶段进入爬行阶段时，它们缩短了脉冲持续时间和脉冲间隔，并降低了频率成分。讨论了背景回波和环境噪声对蝙蝠性能的潜在干扰。蝙蝠对旋转目标的偏好可能是因为旋转目标比静止目标具有更高的释放价值。
