| 摘要 |
PURPOSE: To find a water level without an error by receiving pulse waves from a sound wave pulse generator by a plurality of microphones provided at a fixed interval and measuring time interval between an advancing wave and a reflection wave which are received by the first microphone and a reception time interval of a microphone which is the closest to a water surface. CONSTITUTION: A sound wave pulse generator 1 is provided at an upper end of a waveguide 2, a microphone 51 is provided at an interval L in the lower part thereof, and microphones 52 , 53 ,... 5n are provided sequentially at an interval 1. The generator 1 is driven by pulses from an oscillator 6 to propagate sound wave pulses along the waveguide 2. The microphone 51 and the microphone 5n which is selected in a switch circuit 4 and is the closest to a water surface are connected to an amplifier 7. Its output enters an operation controller 10 through a detector 8 and a waveform forming device 9. The controller 10 measures an interval t2 between an advancing wave and a reflection wave which are received by the microphone 51 and a reception interval t1 of the microphones 51 and 52 to measure an accurate water level. It also becomes possible to provide it along an inclined face and it is unnecessary to erect a vertical tower. |
