| 摘要 |
PURPOSE:To accurately measure a water level, by mounting ultrasonic transmitters to a plurality of buoys and calculating the water level of each buoy from the delay time of a transmitted ultrasonic wave to measure the water level of a reservoir. CONSTITUTION:A water level detection apparatus 1 is constituted so that, for example, the buoy Ai of a plurality of buoys transmits an ultrasonic wave from the transmitter mounted therein and an ultrasonic receiver B receives said ultrasonic wave to inform the reception thereof to the detection apparatus 1. The detection apparatus 1 calculates the time ti, required before the ultrasonic wave reaches the receiver B from the buoy Ai, from the difference between the receiving time and the transmitting time to calculate the distance li between the buoy Ai and the receiver B from the speed (v) and time ti of the ultrasonic wave. Because the horizontal distance L between the receiver B and the buoy Ai and the height Ho between the receiver B and the bottom of water are known, a water level Hi is calculated. The water levels of the buoys A1-An are calculated to measure an average water level H. |
