2012 年 48 巻 3 号 p. 183-187
It is common knowledge that the receiving distance of ultrasound in water varies in inverse proportion to the transmitting frequency. However, empirical data has been obtained mostly from experiments in water tanks and this relation has not been sufficiently tested in ultrasonic biotelemetry under field conditions or moving objects. In this study we investigated the effect of transmitting frequencies of 51, 63, and 78kHz on receiving distance under field conditions when the transmitter and receiver were either drifting, approaching or getting farther in relation to each other. The results show that receiving distance estimated in the field is shorter than that in water tanks and that unlike in the latter it is virtually constant with moving objects regardless of the transmitting frequency.