| 摘要 |
<p>Height-measuring system for measuring the instantaneous height of a vessel, such as a hovercraft, above the water surface using a number of height- measuring devices and an electronic control and processing unit. At least one ultrasonic transmit-receive transducer (1) and two other height-related transducers (2,3) are used as height-measuring devices, ultrasonic waves being emitted in the direction of the water surface by the at least one ultrasonic transducer and being received by it after reflection thereat, and additional height-related information being determined by the other two transducers. The analog output signals of the transducers are fed to the electronic control and processing unit (7), in which they are processed to obtain the height of the said water surface. The at least three transducers are mounted above the water surface in a fixed distance relationship with respect to a reference plane extending perpendicularly to the axis of the vessel mast. The electronic control and processing unit has an anti-aliasing filter (4), an analog-digital converter (5) and a finite impulse response filter (6) for each analog output signal. The water height at an arbitrary position is calculated with the aid of these digital data in the control and processing unit (7), each transducer having coordinates x and y in the reference plane. The height z of the water surface is determined for each transducer, the mean water surface being reproduced with respect to the said reference surface by z = R.x + P.y + H, where the variable z is the height of the water surface at the point determined by the coordinates x, y of said point and the parameters R, P and H are unknown variables. <IMAGE></p> |
