| 摘要 |
PROBLEM TO BE SOLVED: To accurately measure a distance between a transmitter and a receiver.SOLUTION: The receiver 200 is a measuring device which measures a distance from the transmitter 100 for transmitting signals in water by ultrasonic waves with two or more different frequencies, and which extracts two or more signals respectively from the ultrasonic waves transmitted from the transmitter 100 depending on frequencies, and obtains the distance from the transmitter 100 based on a difference value indicating an intensity difference of the two or more extracted signals, a first constant indicating an intensity difference of two or more signals when the distance from the transmitter 100 is known, and a second constant indicating a difference of intensity change of the signals depending on the distance in the two or more frequencies of transmitted signals. |
