| 摘要 |
PURPOSE:To make it possible to measure a flow speed with high accuracy even in a small diameter pipeline, by providing a delay time during a time from the reception of an ultrasonic pulse to the re-transmission thereof while jitter is applied to the delay time. CONSTITUTION:A transmission and reception repeating part 5A repeatedly transmits an ultrasonic pulse to ultrasonic oscillators 2, 3 mounted to a tube 1 through a change-over switch 4 while a delay circuit 20 for providing a predetermined delay time during a time from the reception of an ultrasonic echo to the next transmission and applying jitter to said dalay time is mounted. In this case, a variable frequency oscillation part 23 connected to the repeating part 5A oscillates frequency corresponding to the propagation time of the ultrasonic pulse between the oscillators 2, 3 and this oscillated frequency is calculated by an up-down counter 11. By this method, the influence of residual echo to a receiving wave can be removed in a relatively short delay time and, therefore, a flow speed can be measured with good accuracy even in a small diameter pipeline. |
