| 摘要 |
PROBLEM TO BE SOLVED: To obtain an ultrasonic flow-velocity measuring method in which the difference in the propagation time between downstream-side received waves and upstream-side received waves can be measured by a method wherein triangular waves which rise proportionally rectilinearly are output in synchronization with a time in which the downstream-side received waves become a reference value and the voltage value of the triangular waves is found at a time when the upstream-side received waves become a reference value. SOLUTION: Ultrasonic waves and clock waves are output simultaneously from an upstream- side transmitter 2a, a downstream-side transmitter 2b and a clock circuit 6 by using the driving pulse of a pulse generation circuit 4. Forward ultrasonic waves are received by a downstream-side receiver 3a, and a forward received signal is output from a reception circuit 5. The clock waves from the output start of the ultrasonic waves up to the reception of the forward ultrasonic waves are counted by a counter 7, and the propagation time of the forward ultrasonic waves is found. An integrating circuit 9 outputs triangular waves in which a rise part becomes rectilinear by the received signal of the forward ultrasonic waves. Reverse ultrasonic waves are received by an upstream-side receiver 3b, and the received signal of the reverse ultrasonic waves is output from the reception circuit 5. The voltage value of the triangular waves at this time is held by a peak-hold circuit 11, and the difference in the propagation time between both received waves is found by a computing circuit 12 via an A/D conversion circuit 11. |
