Low-power consumption ultrasonic wave transmitting time measuring method and circuit

Abstract

The invention discloses a low-power consumption ultrasonic wave transmitting time measuring method and circuit. In a traditional ultrasonic wave transmitting time measuring method, a hardware threshold value method is adopted, the power consumption is large, and the measuring precision is low. The circuit comprises a first ultrasonic transducer, a second ultrasonic transducer, an analog switch unit, a bandpass filtering unit, a comparing unit, a driving unit, a power supply controlling and voltage stabilizing unit, a time measuring unit, a temperature detecting unit and a single chip microcomputer unit. According to the low-power consumption ultrasonic wave transmitting time measuring method, a variable time delay filtering method is adopted, the arriving time of an echo signal is accurately captured by setting a threshold value, and the ultrasonic wave transmission time is precisely calculated; through the design of software and the hardware circuit, the power consumption of a whole system is reduced, and the device cost is saved.

Description

technical field [0001] The invention belongs to the technical field of flow detection, and relates to a method and circuit for measuring low-power ultrasonic flow. Background technique [0002] Compared with other types of flowmeters, ultrasonic flowmeters have the advantages of high precision, high repeatability, low pressure drop and bidirectional measurement. It is widely used in the fields of environmental protection, industry, energy transportation and daily life. Ultrasonic flowmeter is designed according to the principle of forward-countercurrent time difference method of ultrasonic waves in fluid propagation. The flow velocity of fluid is related to sound speed and time difference. At different temperatures, the speed of sound is not a constant, it will change with temperature, which will cause flow measurement errors, as well as changes in acoustic resistance and sound wave attenuation. In the measurement principle of the time difference method, the accurate measu...

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Problems solved by technology

Usually the echo signal is doped with more interference signals. When the peak value of the interference signal reaches the set value of the comparator, the comparator will misjudge the arrival of the echo signal, thus affecting the measurement accuracy of forward and reverse flow transit time.

If the threshold voltage is set between the first and second peaks of the echo signal, although the misjudgment of the arrival time of the ultrasonic signal will be reduced, as the temperature of the fluid changes, the amplitude of the ultrasonic signal will change, and the transmission of the ultrasonic wave will The time will also change, and the misjudgment of the arrival time of the ultrasonic signal will also occur, thereby reducing the measurement accuracy of the transit time

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