Design of a transducer-driving system scanning around an aquatic target in an indoor tank

Abstract

A squid has been specified as a kind of fish that has to been managed scientifically. Estimation of its resources via acoustic surveys is required. But the basic data of the target strength (TS) of a squid are limited. So far, in the measurements of the TS pattern of fish, echo levels are observed while changing the aspect of a fish. On the other hand, since a squid is more fragile than a fish, and unstable in shape, the rotating unit of fish is not available for a squid. So the positioning system that makes a transducer scan precisely around an aquatic target suspended in the water has been designed. This system is loaded in the electric flatcar, the probe of which can move three dimensionally, on the top of a tank which is 10 m in width, 15 m in length, and 10 m in depth. It is hoped that precise TS pattern measurements are possible so that the target is suspended without damage owing to this transducer-driving system. The detail of control software and an example of measurements and subjects are described in this paper.