Patent ID: 8971150
Filing Date: 2015-03-03
Classification: G01C,G01S

Abstract:
1. A method for measuring sea waves by means of ultrasonic waves, for measuring wave heights in predetermined waters by detecting a fluctuation of a floating body on a sea surface, the method comprising: receiving ultrasonic waves emitted from at least three ultrasonic transmitters on or in the vicinity of a seabed below the floating body moored on the sea surface of the predetermined waters with an ultrasonic receiver provided below the sea surface on the floating body; detecting distances between the ultrasonic transmitters and the ultrasonic receiver based on propagation time since the ultrasonic waves are emitted from the ultrasonic transmitters until the ultrasonic waves are received; high-pass filtering the distance data to extract short-term fluctuation components; and preparing linear equations with three unknowns for the respective ultrasonic transmitters such that the extracted short-term fluctuation component is equal to the displacement of the ultrasonic receiver and the displacement of the ultrasonic receiver is represented by three unknowns (x, y, z ) on the three-dimensional coordinate axes, and solving the simultaneous linear equations with three unknowns to determine at least the displacement in a height direction of the short-term fluctuation component and obtain a wave height wherein the wave height is a component of the short-term fluctuation component.