| 摘要 |
PURPOSE:To perfectly measure and display the whole cross-sectional shape of a fishing net by measuring by measuring the shape of the net on the surface of water with a navigation device of a ship, indirectly measuring the cross-sectional shape of the net at a certain depth with a tidal flow meter and displaying the shape of the net of the basis of the measured results. CONSTITUTION:The position of a ship itself moving while placing a carrying net in water is set by ship position-setting means 8. A signal displaying the track of the ship itself on the basis of the output signal of the means 8 is produced by a track signal-producing means 7. An ultrasonic pulse signal is discharged into the water by a tidal flow-measuring means 11 and the reflected wave is received to measure the direction and speed of the tidal flow at least one depth with the utilization of Doppler effect. A signal displaying the cross-sectional shape of the net at the above-mentioned depth is produced based on the output signal of the means 8 and on the direction and speed data of the tidal flow outputted by the means 11 is produced by a net shape signal-producing means 7. The track of the ship and the shape of the net are displayed on the basis of the output signals of a memory 10 memorizing the signals of the means 7 by a display 1. |
