| 摘要 |
FIELD: physics. ^ SUBSTANCE: flow metre, having a pair of ultrasonic transducers, is switched from passive state to active state at time intervals measured by a clock pulse generator. In active mode, at least one pair of ultrasonic signals is emitted and received. The transmission time of each ultrasonic signal is measured by a counter which is clocked by a high-speed clock pulse generator. The phase of the emitted and received signals is compared. A pulsed signal with duration whose duration is measured depending on the phase comparison result is obtained using a phase comparator. A capacitor is charged using the pulsed signal. Voltage across the capacitor is measured using a reading device. A microprocessor calculates flow rate based on the measured transmission time and voltage, and switches the ultrasonic flow metre from active state to passive state after completing calculation. The ultrasonic transducers, high-speed clock pulse generator, phase comparator and reading device, which are components of the ultrasonic flow metre, function only in active state. ^ EFFECT: invention can work on batteries for up 10 years, provide automatic calibration and correction of parameters of circuit components. ^ 19 cl, 5 dwg |
