| 摘要 |
PROBLEM TO BE SOLVED: To provide a ship speed measuring instrument capable of calculating an accurate ship speed by one ultrasonic beam even when pitching is generated in a ship. SOLUTION: A shaking sensor 28 such as a GPS posture measuring instrument or the like is provided to a ship 2 for transmitting and receiving ultrasonic beam B at a dipθin a bow direction. When pitching is generated by inclinationα, the ship speed V of the ship after correction can be calculated according to the formula; V=C.Δf/ 2f.cos(θ+α)} [wherein, (f) is the frequency of emitted ultrasonic waves,θis a reference dip [the dip of a horizontal surface 4 with an emission direction (ultrasonic beam) at a time when there is no shaking], C is sonic velocity in water, andΔf is Doppler shift of reflected waves from the bottom of the water (difference between transmission frequency and reception frequency)]. |
