| 摘要 |
PROBLEM TO BE SOLVED: To obtain a metering fish finder by which data on the distribution density or the like of a fish school can be acquired in a short time and with high accuracy. SOLUTION: A transmission part 1 is formed as a circuit which generates a transmission signal SS having a pulse width designated by a pulse-width changeover control signal PWSC. A pulse-width changeover control part 9 which generates a pulse-width changeover control signal PWSC used to automatically change over a short pulse width and a long pulse width alternately is installed. A signal separator 5 which separates the output of a reception part 4 into a short pulse-width signal component and a long pulse-width signal component is installed. The short pulse-width signal component is supplied to a single- body echo processing part 6. The long pulse-width signal component is supplied to a group-body echo processing part 7. A volume scattering intensity SV per unit volume which is found by its group-body echo signal processing part 71 is divided by an average target strength TS from the single-body echo processing part 6, and the distribution density (n) of a fish school is found. |
