| 摘要 |
PURPOSE:To make it possible to measure accurately a flow rate in a pipe by inputting a pulse-string signal to an ultrasonic transmitter and by making a comparing decision on wether this signal and a signal received by an ultrasonic receiver are composed of substantially the same pulse string or not. CONSTITUTION:On the external pipe 2 where fluid 1 flows, the signals processing part composed of ultrasonic transmitter 3, receiver 4 receiving its output, amplifier 10 amplifying a received signal, discriminator 11 generating an output pulse at the time of more than a fixed level, gate circuits G1-G6 processing its output, monostable multivibrators MM1-MM9, time-difference measuring circuits TM1- TM3, integral holding circuits IS1-IS7, level comparators CM1-CM4, and AND circuits 19 and 20, the transmission part composed of oscillator 21 driving the transmitter, pulse-string signal generator 22, trigger signal generator 23, and reset signal generator 24, and flow-rate display meter 25 are arranged. Only when the pulse string of the pulse-string signal after the comparing decision is substantially equal, the flow rate is displayed 25, so that the display of an incorrect flow rate will never be made even if an abnormal signal arrives. |
