UNDERWATER POSITION DETECTION SYSTEM, ULTRASONIC TRANSMISSION MEANS AND SHIP SIDE RECEPTION MEANS USED FOR UNDERWATER POSITION DETECTION SYSTEM, AND UNDERWATER POSITION DETECTION METHOD

PROBLEM TO BE SOLVED: To provide underwater position detection means capable of accurately ascertaining a three-dimensional position of a diver viewed from a mother ship.SOLUTION: An underwater position detection system 11 is a system for receiving ultrasound 20 transmitted from an ultrasonic transmitter 12 attached to a diver A side, at a ship side receiver 13 provided on a ship S side, to detect a position of a diver A under water. The ship side receiver 13 has an ultrasound receiver 21 having a plurality of ultrasonic microphones 18, a comparator 23 for outputting a time difference τ between a transmission synchronizing signal 22S and an ultrasound signal, a distance computing device 24 for calculating a distance L between the diver A and the ultrasonic microphone 18 based on the time difference τ output by the comparator 23, a coordinate computing device 25 for calculating three-dimensional coordinates of the diver A based on the distance L, and an image display device 26 for displaying the coordinates of the diver A in an image.