Measuring circuit for measuring supersonic wave level meter transit time

Abstract

The utility model discloses a circuit for measuring the transmit time of a ultrasonic level transmitter, comprising a transmit power amplifying circuit module (5) and a echo amplifying comparison circuit module (6) and a FPGA module (7), which is characterized in that the utility model is embedded into a soft core microcontroller with field programmed gate array Cyclone EP1C6Q240,multiplies the input signal of low-frequency active crystal oscillator to 50MHz as the system clock with the phase locked loop and frequency multiplier circuit (The operation frequency of the whole FPGA system is 50 MHz), write ultrasonic transmitting control logic and ultrasonic receiving control logic with Verilog language. The measurement of ultrasonic transmitting time is realized by the FPGA hardware completely, so that the measuring resolution is improved to 20ns.

Description

technical field [0001] The invention relates to a measuring circuit for measuring time, in particular to a measuring circuit for measuring the transit time of an ultrasonic level measuring instrument. Background technique [0002] The measurement principle of the ultrasonic liquid level / level gauge is as follows: the ultrasonic wave emitted by the ultrasonic transducer (sensor) encounters the phase interface of the measured material and then reflects (echo), and the trigger pulse time of the ultrasonic transducer (sensor) is measured The echo generated by the ultrasonic wave meeting the measured liquid level / level interface returns to the arrival time; the difference between the two moments is called the "transit time" of ultrasonic measurement. From the transit time and the sound velocity of the sound wave in the transmission medium, the measured liquid level / level value can be easily calculated. [0003] Ultrasonic liquid level / level gauge, the key to improving the measur...

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Problems solved by technology

[0006] Since the speed of sound is greatly affected by the temperature, density, and pressure of the propagation medium air, the general method that can be used is temperature compensation for the speed of sound, but there is no ideal compensation method for the change of sound speed caused by air density and pressure, so it is still necessary to measure the speed of sound. There are some errors,

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