JPS54149671A - Ultrasonic wave type measuring device - Google Patents

Abstract

PURPOSE:To detect the ultrasonic pulses of the next trial in a normal manner thereby to eliminate the error of the measured results by changing the setting of the amplitude monitoring voltage, when the detecting malfunction of ultrasonic pulses takes place, so that the amplification of the received signals is changed. CONSTITUTION:The oscillatory frequency is so varied that the difference signals S between the time for a counter 3 to count the output of an oscillator 1 and the time for the ultrasonic pulses to propagate through the fluid in a pipe 10 may be reduced to zero. The flow speed and rate are measured in accordance with the oscillatory frequency difference when the ultrasonic pulses are projected in the forward and backward directions with respect to the flow of the fluid. In this instance, there are provided an ultrasonic wave receving amplifier 7, a malfunction monitoring circuit 31, an amplitude monitoring circuit 40 having two monitoring voltages, and a mistrigger detecting circuit 41 which is operative to compare the signals R relating the difference signals S with a preset voltage thereby to generate signals F in accordance with the compared results and the malfunction monitoring output signals W. In response to the amplitude monitoring voltage, the amplitude monitoring voltage is changed to change the amplification of the amplifier 7 so that the measured value of the next trial may be normally detected.