| 摘要 |
PURPOSE:To compensate errors based on the change in the temperature of a medium to be measured and others by converging the sum of both frequencies transmitted from a transmitter which is switched to the medium to be measured to a specified value, and measuring the flow rate of the medium to be measured from both frequencies in the converged state. CONSTITUTION:A voltage control type oscillating circuit 10 has oscillators 13 and 15 and supplies an output signal to a pulse generating circuit 27 through a switch 25. A transmitter 35 drives transducers 41 and 43 through a switch 45. The received wave is supplied to a time difference detecting circuit 59 through a receiver 55. A pulse output signal is supplied to a circuit 59 when the counting state of a counter 61 has reached a preset value. A control signal corresponding to the time difference is fed back to the circuit 10. A CPU81 controls a control device 85, variably controls the preset value of the counter 61, and converges the sum of the frequencies of the oscillators 13 and 15 to the specified value. Under this state, the flow speed of the medium to be measured in computed from the frequencies of the oscillators 13 and 15, the flow rate can be obtained, and the errors due to the temperature change can be compensated. |
