| 摘要 |
PURPOSE:To ensure the detection of a medium to be detected by determining the amplitude (gain) of an amplifier so that the loop gain when a space between a wave transmitter and a wave receiver is filled with the medium to be measured is GH >=1, and constituting a delay-line oscillating system. CONSTITUTION:An ultrasonic wave liquid level gage 10 comprises a wave transmitter 11 and a wave receiver 12 which are attached to the symmetrical positions of one horizontal cross section of a liquid container V, an amplifier 18 which receives the output from the wave receiver and amplifies the output, a driving power supply 17 for the ultrasonic wave piezoelectric transducer of the wave transmitter 11 and a display device 20 for displaying the output of the wave receiver 12. With respect to the amplifier 18, the gain G of the amplifier is determined so that the oscillating condition becomes GH >= 1 when the liquid surface is located at the line of the wave transmitter 11 and the wave receiver 12 and the container V is made to be the delaying element of an attenuating rate H. Namely, the liquid level gate 10 constitutes the delay-line oscillating system when the liquid reaches the line of the wave transmitter 11 and the wave receiver 12. Conversely, when the liquid surface does not reach the above described line, the oscillating condition is not satisfied, and the oscillation does not occur. |
