| 摘要 |
PURPOSE:To stabilize the indication of an ultrasonic level meter by using the simulated received pulses corresponding to the waves reflected from the most distant point of a measuring span. CONSTITUTION:The ultrasonic pulses from an intermittent oscillator 3 are fed from a transmitting and receiving device 5 to the inside of a hopper 6, and the reflected waves from the content of the hopper 6 are received so that the level of the content is indicated in accordance with the time difference. At this time, there is provided a circuit 17 for generating simulated received pulses which have the time difference corresponding to the reflected waves at the most distant point of the measuring span, i.e., when the hopper is under its substantially vacant condition. These pulse output and the output of the AND circuit, i.e., the received signals are fed to an OFF circuit 18 so that the logic signals become the reset input of an FF 12. As a result, in case no received signal can be obtained at the output of an AND circuit 11, the FF 12 is reset so that the deflection of the level meter 16 can be stabilized without any indication of the abnormal value of an integrating circuit 14. |
