Circuit and method for ultrasonic measurement of gas flow

Abstract

The application relates to the technical field of integrated circuit design, and discloses an ultrasonic wave circuit and method for measuring gas flow, which comprises an uplink transducer, a downlink transducer and a controller. The uplink transducer is used for receiving an uplink differential pulse sequence to generate the uplink ultrasonic wave signal and receiving and forwarding the downlink ultrasonic wave signal. The downlink transducer is used for receiving a downlink differential pulse sequence to generate the downlink ultrasonic wave signal and receiving and forwarding the uplink ultrasonic wave signal. The controller is used for controlling the generation of the uplink differential pulse sequence and the downlink differential pulse sequence, receiving the downlink ultrasonic wave signal forwarded by the uplink transducer and the uplink ultrasonic wave signal forwarded by the downlink transducer after being amplified and analog-to-digital converted in sequence, and calculating the corresponding time of flight based on the received downlink ultrasonic wave signal and the uplink ultrasonic wave signal, so as to calculate the actual gas flow. The application adopts the differential excitation transducer mode, greatly increases the transducer signal amplitude, and improves the signal-to-noise ratio.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of integrated circuit design, in particular to an ultrasonic wave circuit and method for measuring gas flow. BACKGROUND

[0002] The ultrasonic wave gas meter technology is advanced and has obvious advantages, and is an important direction for the development of gas metering. However, due to the large attenuation of gas to ultrasonic wave signals, the problem of low signal-to-noise ratio often needs to be faced when testing gas flow. When testing complex gas, the signal-to-noise ratio is further reduced, resulting in unstable time-of-flight calculation results, thereby affecting the accuracy and stability of gas flow measurement.

[0003] The prior art usually adopts a single-ended mode to excite the transducer, and the positive terminal of the transducer receives the excitation signal and the negative terminal is grounded. In the battery-powered system such as the ultrasonic gas meter, the signal amplitude of the single-ended transducer is limited, which affects the accuracy and stability of the flow test.

[0004] The application CN105115553A measures gas flow by time difference method, which can improve the accuracy of flow test to a certain extent, but the first ultrasonic wave transducer, the second ultrasonic wave transducer, the third ultrasonic wave transducer and the fourth ultrasonic wave transducer all adopt the single-ended transducer excitation mode. When the excitation signal is weak, the problem of limited signal amplitude of the emitted signal cannot be avoided, thereby causing the problems of insufficient accuracy and poor stability of the flow test.

[0005] Based on this technical background, the present application studies an ultrasonic wave circuit and method for measuring gas flow. SUMMARY

[0006] In view of the shortcomings of the prior art, the present application provides an ultrasonic wave circuit and method for measuring gas flow. The circuit adopts a differential excitation transducer mode, which can greatly increase the transducer signal amplitude without changing the power supply voltage, thereby improving the signal-to-noise ratio and further improving the accuracy and stability of the flow measurement.

[0007] To achieve the above purpose, the first aspect of the present application provides an ultrasonic wave circuit for measuring gas flow, comprising:

[0008] An uplink transducer for receiving an uplink differential pulse sequence and exciting to generate the uplink ultrasonic wave signal, and for receiving and forwarding the downlink ultrasonic wave signal;

[0009] A downlink transducer for receiving a downlink differential pulse sequence and exciting to generate the downlink ultrasonic wave signal, and for receiving and forwarding the uplink ultrasonic wave signal;

[0010] a controller configured to control generation of the up differential pulse sequence and the down differential pulse sequence, and to receive the down ultrasonic wave signal forwarded by the up transducer and the up ultrasonic wave signal forwarded by the down transducer after being amplified and analog-to-digital converted in sequence, and to calculate the time of flight based on the received down ultrasonic wave signal and up ultrasonic wave signal, thereby calculating the flow rate of the actual gas;

[0011] The up transducer is configured to generate the up ultrasonic wave signal at a different time than the down transducer is configured to generate the down ultrasonic wave signal.

[0012] The present application provides a method for ultrasonic wave measurement of gas flow rate in the above-mentioned circuit, comprising:

[0013] The controller controls generation of the up differential pulse sequence and sends it to the up transducer.

[0014] After receiving the up differential pulse sequence, the up transducer is configured to generate the up ultrasonic wave signal, and the down transducer is configured to receive and forward the up ultrasonic wave signal.

[0015] The forwarded up ultrasonic wave signal is sent to the controller after being amplified and analog-to-digital converted in sequence.

[0016] The controller controls generation of the down differential pulse sequence and sends it to the down transducer.

[0017] After receiving the down differential pulse sequence, the down transducer is configured to generate the down ultrasonic wave signal, and the up transducer is configured to receive and forward the down ultrasonic wave signal.

[0018] The forwarded down ultrasonic wave signal is sent to the controller after being amplified and analog-to-digital converted in sequence.

[0019] The controller calculates the time of flight based on the received down ultrasonic wave signal and up ultrasonic wave signal, thereby calculating the flow rate of the actual gas.

[0020] The up transducer is configured to generate the up ultrasonic wave signal at a different time than the down transducer is configured to generate the down ultrasonic wave signal.

[0021] The present application has the following advantages:

[0022] The ultrasonic gas flow measurement circuit provided by the present application generates an uplink differential pulse sequence and a downlink differential pulse sequence through control, receives the downlink ultrasonic signals forwarded by the uplink transducer and the uplink ultrasonic signals forwarded by the downlink transducer in sequence through amplification and analog-to-digital conversion, calculates the corresponding time of flight based on the received downlink ultrasonic signals and uplink ultrasonic signals, and thus calculates the actual gas flow. The overall circuit adopts the differential excitation transducer mode, which can greatly increase the transducer signal amplitude without changing the power supply voltage, thereby improving the signal-to-noise ratio and further improving the precision and stability of the flow measurement.

[0023] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0024] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference characters refer to like parts throughout the several views.

[0025] Figure 1 The structure diagram of one specific embodiment of the ultrasonic gas flow measurement circuit provided by the present application.

[0026] BRIEF DESCRIPTION OF DRAWINGS

[0027] K1- first single-pole double-throw switch, K2- second single-pole double-throw switch, K3- third single-pole double-throw switch, K4- fourth single-pole double-throw switch, K5- first single-pole single-throw switch, K6- second single-pole single-throw switch, R- resistance. DETAILED DESCRIPTION

[0028] Preferred embodiments of the present application will be described in more detail below. Although the preferred embodiments of the present application are described below, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein.

[0029] In the present application, the orientation words such as "up, down" used without the opposite description generally refer to the up and down of the device in the normal use state, and "inner, outer" refers to relative to the device profile. In addition, the terms "first, second, third" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first, second, third" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0030] The present application provides an ultrasonic gas flow measurement circuit, as shown inFigure 1 As shown, comprising:

[0031] The uplink transducer is used for receiving the uplink differential pulse sequence and exciting the uplink ultrasonic signal, and is also used for receiving and forwarding the downlink ultrasonic signal.

[0032] The downlink transducer is used for receiving the downlink differential pulse sequence and exciting the downlink ultrasonic signal, and is also used for receiving and forwarding the uplink ultrasonic signal.

[0033] The controller is used for controlling the generation of the uplink differential pulse sequence and the downlink differential pulse sequence, and is also used for receiving the downlink ultrasonic signal forwarded by the uplink transducer and the uplink ultrasonic signal forwarded by the downlink transducer after being amplified and analog-to-digital converted in sequence, and is also used for calculating the corresponding flight time based on the received downlink ultrasonic signal and uplink ultrasonic signal, so as to calculate the flow of the actual gas.

[0034] The uplink transducer excites the uplink ultrasonic signal at a different time from the downlink transducer exciting the downlink ultrasonic signal.

[0035] In the present application, by controlling the generation of the uplink differential pulse sequence and the downlink differential pulse sequence, and receiving the downlink ultrasonic signal forwarded by the uplink transducer and the uplink ultrasonic signal forwarded by the downlink transducer after being amplified and analog-to-digital converted in sequence, and simultaneously calculating the corresponding flight time based on the received downlink ultrasonic signal and uplink ultrasonic signal, the flow of the actual gas is calculated. The overall circuit adopts the differential excitation transducer mode, which can greatly increase the transducer signal amplitude without changing the power supply voltage, thereby improving the signal-to-noise ratio and further improving the accuracy and stability of the flow measurement.

[0036] According to the present application, it also comprises:

[0037] The first single-pole double-throw switch K1 has a normally closed point connected to one end of the uplink transducer and a normally open point connected to one end of the downlink transducer.

[0038] The second single-pole double-throw switch K2 has a normally closed point connected to the other end of the uplink transducer and a normally open point connected to the other end of the downlink transducer.

[0039] The third single-pole double-throw switch K3 has a normally closed point connected to one end of the downlink transducer and a normally open point connected to one end of the uplink transducer.

[0040] The fourth single-pole double-throw switch K4 has a normally closed point connected to the other end of the downlink transducer and a normally open point connected to the other end of the uplink transducer, and a blade end connected to the ground.

[0041] According to the present application, it also comprises:

[0042] The first single-pole single-throw switch K5 has a blade end connected with one end of the uplink transducer, and a holding end connected with the other end of the uplink transducer through a resistor R;

[0043] The second single-pole single-throw switch K6 has a blade end connected with one end of the downlink transducer, and a holding end connected with the other end of the downlink transducer through a resistor R;

[0044] The first single-pole double-throw switch K1, the second single-pole double-throw switch K2, the third single-pole double-throw switch K3, the fourth single-pole double-throw switch K4, the first single-pole single-throw switch K5 and the second single-pole single-throw switch K6 are controlled by the controller.

[0045] According to the application, further comprising:

[0046] A pulse generator having a control end connected with the controller, and being used to generate the uplink pulse sequence and the downlink pulse sequence under the control of the controller;

[0047] A driver having an input end connected with an output end of the pulse generator, and an output end connected with the blade end of the first single-pole double-throw switch K1 through a resistor R, and being used to generate a same-phase pulse sequence with enhanced driving capacity and a phase difference of 0 degree with the uplink pulse sequence and the downlink pulse sequence;

[0048] An inverter having an input end connected with an output end of the pulse generator, and an output end connected with the blade end of the second single-pole double-throw switch K2 through a resistor R, and being used to generate an inverted pulse sequence with a phase difference of 180 degrees with the uplink pulse sequence and the downlink pulse sequence.

[0049] According to the application, further comprising:

[0050] An amplifier having an input end connected with the blade end of the third single-pole double-throw switch K3 through a resistor R, and being used to amplify the downlink ultrasonic wave signal transmitted by the uplink transducer and the uplink ultrasonic wave signal transmitted by the downlink transducer;

[0051] An ADC acquisition module having an input end connected with an output end of the amplifier, and an output end connected with the controller, and being used to perform analog-digital conversion on the signal output by the amplifier and send the digital signal to the controller.

[0052] In the application, the series resistor on each signal transmission path has a value of 10-100 ohms, and is used to form an RC circuit with a distributed capacitor, so as to smooth the signal edge, and reduce high-frequency noise and overshoot problems.

[0053] The application further provides a method for measuring gas flow by ultrasonic waves in the above-mentioned circuit, comprising:

[0054] The controller controls to generate the uplink differential pulse sequence, and sends it to the uplink transducer;

[0055] After receiving the uplink differential pulse sequence, the uplink transducer is excited to generate an uplink ultrasonic signal, and the downlink transducer receives and transmits the uplink ultrasonic signal.

[0056] The transmitted uplink ultrasonic signal is amplified and analog-to-digital converted in sequence and then sent to the controller.

[0057] The controller controls the generation of a downlink differential pulse sequence and sends it to the downlink transducer.

[0058] After receiving the downlink differential pulse sequence, the downlink transducer is excited to generate a downlink ultrasonic signal, and the uplink transducer receives and transmits the downlink ultrasonic signal.

[0059] The transmitted downlink ultrasonic signal is amplified and analog-to-digital converted in sequence and then sent to the controller.

[0060] The controller calculates the corresponding time of flight based on the received downlink ultrasonic signal and uplink ultrasonic signal, thereby calculating the actual gas flow.

[0061] The uplink transducer excites to generate an uplink ultrasonic signal at a different time than the downlink transducer excites to generate a downlink ultrasonic signal.

[0062] According to the application, the controller controls the generation of an uplink differential pulse sequence and sends it to the uplink transducer, which includes:

[0063] The controller controls the generation of an uplink differential pulse sequence and controls the closing of the normally closed points of the first single-pole double-throw switch K1 and the second single-pole double-throw switch K2, and the closing of the first single-pole single-throw switch K5, thereby sending the uplink differential pulse sequence to the uplink transducer.

[0064] The uplink transducer excites to generate an uplink ultrasonic signal, and the downlink transducer receives and transmits the uplink ultrasonic signal, which includes:

[0065] While the uplink transducer excites to generate an uplink ultrasonic signal, the controller controls the closing of the normally closed points of the third single-pole double-throw switch K3 and the fourth single-pole double-throw switch K4, and the opening of the second single-pole single-throw switch K6, thereby the downlink transducer receives and transmits the uplink ultrasonic signal.

[0066] According to the application, the controller controls the generation of a downlink differential pulse sequence and sends it to the downlink transducer, which includes:

[0067] The controller controls the generation of a downlink differential pulse sequence and controls the closing of the normally open points of the third single-pole double-throw switch K3 and the fourth single-pole double-throw switch K4, and the closing of the second single-pole single-throw switch K6, thereby sending the downlink differential pulse sequence to the downlink transducer.

[0068] The downlink transducer excites to generate a downlink ultrasonic signal, and at the same time, the uplink transducer receives and transmits the downlink ultrasonic signal, which comprises:

[0069] The downlink transducer excites to generate a downlink ultrasonic signal, and at the same time, the controller controls the normally open point of the first single-pole double-throw switch K1 and the second single-pole double-throw switch K2 to be attracted, and the first single-pole single-throw switch K5 to be disconnected, and then the uplink transducer receives and transmits the downlink ultrasonic signal.

[0070] According to the application, the controller controls to generate an uplink differential pulse sequence, which comprises:

[0071] The controller controls the pulse generator to generate an uplink pulse sequence;

[0072] The uplink pulse sequence is sent to the driver and the inverter respectively, and at the output end of the driver, an uplink in-phase pulse sequence with enhanced driving ability and a phase difference of 0 degrees from the uplink pulse sequence is obtained, and at the output end of the inverter, an uplink anti-phase pulse sequence with a phase difference of 180 degrees from the uplink pulse sequence is obtained;

[0073] The uplink in-phase pulse sequence and the uplink anti-phase pulse sequence jointly form an uplink differential pulse sequence.

[0074] According to the application, the controller controls to generate a downlink differential pulse sequence, which comprises:

[0075] The controller controls the pulse generator to generate a downlink pulse sequence;

[0076] The downlink pulse sequence is sent to the driver and the inverter respectively, and at the output end of the driver, a downlink in-phase pulse sequence with enhanced driving ability and a phase difference of 0 degrees from the downlink pulse sequence is obtained, and at the output end of the inverter, a downlink anti-phase pulse sequence with a phase difference of 180 degrees from the downlink pulse sequence is obtained;

[0077] The downlink in-phase pulse sequence and the uplink anti-phase pulse sequence jointly form a downlink differential pulse sequence.

[0078] The application will be described in more detail below through specific embodiments.

[0079] Embodiment 1

[0080] As shown in Figure 1 , the embodiment provides an ultrasonic circuit for measuring gas flow, which comprises:

[0081] An uplink transducer for receiving an uplink differential pulse sequence and exciting to generate the uplink ultrasonic signal, and for receiving and transmitting a downlink ultrasonic signal;

[0082] a down transducer for receiving the down differential pulse sequence and exciting the down ultrasonic signal, and for receiving and forwarding the up ultrasonic signal;

[0083] a controller for controlling the generation of the up differential pulse sequence and the down differential pulse sequence, and for receiving the down ultrasonic signal forwarded by the up transducer and the up ultrasonic signal forwarded by the down transducer after being amplified and analog-to-digital converted in sequence, and for calculating the corresponding time of flight based on the received down ultrasonic signal and up ultrasonic signal, thereby calculating the actual gas flow;

[0084] the up transducer excites the up ultrasonic signal at a different time than the down transducer exciting the down ultrasonic signal;

[0085] a first single-pole double-throw switch K1, with a normally closed point connected to one end of the up transducer and a normally open point connected to one end of the down transducer;

[0086] a second single-pole double-throw switch K2, with a normally closed point connected to the other end of the up transducer and a normally open point connected to the other end of the down transducer;

[0087] a third single-pole double-throw switch K3, with a normally closed point connected to one end of the down transducer and a normally open point connected to one end of the up transducer;

[0088] a fourth single-pole double-throw switch K4, with a normally closed point connected to the other end of the down transducer and a normally open point connected to the other end of the up transducer, and a blade end connected to ground;

[0089] a first single-pole single-throw switch K5, with a blade end connected to one end of the up transducer and an attraction end connected to the other end of the up transducer through a resistor R;

[0090] a second single-pole single-throw switch K6, with a blade end connected to one end of the down transducer and an attraction end connected to the other end of the down transducer through a resistor R;

[0091] the first single-pole double-throw switch K1, the second single-pole double-throw switch K2, the third single-pole double-throw switch K3, the fourth single-pole double-throw switch K4, the first single-pole single-throw switch K5, and the second single-pole single-throw switch K6 are all controlled by the controller;

[0092] a pulse generator, with a control end connected to the controller, for generating the up pulse sequence and the down pulse sequence under the control of the controller;

[0093] a driver, with an input end connected to the output end of the pulse generator and an output end connected to the blade end of the first single-pole double-throw switch K1 through a resistor R, for generating a same-phase pulse sequence with enhanced driving capability and a phase difference of 0 degrees with the up pulse sequence and the down pulse sequence;

[0094] The inverter is connected with the output end of the pulse generator, and the output end is connected with the blade end of the second single-pole double-throw switch K2 through a resistor R, and is used for generating an inverted pulse sequence with a phase difference of 180 degrees from the uplink pulse sequence and the downlink pulse sequence.

[0095] The amplifier is connected with the blade end of the third single-pole double-throw switch K3 through a resistor R, and is used for amplifying the downlink ultrasonic signal transmitted by the uplink transducer and the uplink ultrasonic signal transmitted by the downlink transducer.

[0096] The ADC acquisition module is connected with the output end of the amplifier, and is connected with the controller, and is used for converting the signal output by the amplifier into a digital signal and sending the digital signal to the controller.

[0097] In the embodiment, the value of the series resistance on each signal transmission path is 10-100 ohms, which is used to form an RC circuit with the distributed capacitance, so as to smooth the signal edge, reduce high-frequency noise and overshoot problem.

[0098] The ultrasonic wave measures the gas flow rate, and the flight time of the uplink and downlink signals of the ultrasonic wave needs to be tested respectively, so as to calculate the flow rate of the gas, and the embodiment provides a method for measuring the gas flow rate by ultrasonic wave, which comprises:

[0099] When measuring the uplink signal, the normally closed points of the first single-pole double-throw switch K1, the second single-pole double-throw switch K2, the third single-pole double-throw switch K3 and the fourth single-pole double-throw switch K4 are attracted, the first single-pole single-throw switch K5 is attracted, the second single-pole single-throw switch K6 is disconnected, the controller controls the pulse generator to output a pulse sequence, and after passing through the driver and the inverter, two signals with the same amplitude but with a phase difference of 180 degrees are output and applied to the two ends of the uplink transducer, so as to excite the uplink transducer to output an ultrasonic signal;

[0100] The downlink transducer receives the ultrasonic signal, converts it into a digital signal through the amplifier and the ADC acquisition module, and receives the digital signal by the controller;

[0101] When measuring the downlink signal, the normally open points of the first single-pole double-throw switch K1, the second single-pole double-throw switch K2, the third single-pole double-throw switch K3 and the fourth single-pole double-throw switch K4 are attracted, the second single-pole single-throw switch K6 is attracted, the first single-pole single-throw switch K5 is disconnected, the controller controls the pulse generator to output a pulse sequence, and after passing through the driver and the inverter, two signals with the same amplitude but with a phase difference of 180 degrees are output and applied to the two ends of the downlink transducer, so as to excite the downlink transducer to output an ultrasonic signal;

[0102] The uplink transducer receives the ultrasonic signal, converts it into a digital signal through the amplifier and the ADC acquisition module, and receives the digital signal by the controller;

[0103] The controller calculates the corresponding flight time according to the collected data of the received uplink and downlink signals, so as to calculate the actual gas flow.

[0104] The circuit for measuring gas flow by ultrasonic waves provided by the embodiment of the present application controls the generation of uplink differential pulse sequence and downlink differential pulse sequence, receives the downlink ultrasonic waves forwarded by the uplink transducer and the uplink ultrasonic waves forwarded by the downlink transducer after being amplified and analog-digital converted in sequence, and calculates the corresponding flight time based on the received downlink ultrasonic waves and uplink ultrasonic waves, so as to calculate the actual gas flow. The overall circuit adopts the differential excitation transducer mode, can greatly increase the transducer signal amplitude without changing the power supply voltage, so as to improve the signal-to-noise ratio, and further improve the precision and stability of the flow measurement.

[0105] The above has described the embodiments of the present application, the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A circuit for ultrasonically measuring the flow of a gas, characterized by, include: The uplink transducer is used to receive uplink differential pulse sequences and generate uplink ultrasonic signals, and also to receive and forward downlink ultrasonic signals; The downlink transducer is used to receive the downlink differential pulse sequence and generate the downlink ultrasonic signal, and is also used to receive and forward the uplink ultrasonic signal; The controller is used to control the generation of the uplink differential pulse sequence and the downlink differential pulse sequence, and to receive the downlink ultrasonic signal forwarded by the uplink transducer after being amplified and converted from analog to digital, and the uplink ultrasonic signal forwarded by the downlink transducer. It is also used to calculate the corresponding flight time based on the received downlink ultrasonic signal and uplink ultrasonic signal, thereby calculating the flow rate of the actual gas. The uplink transducer generates the uplink ultrasonic signal, but this does not occur simultaneously with the downlink transducer generating the downlink ultrasonic signal. The first single-pole double-throw switch has its normally closed contact connected to one end of the upward transducer and its normally open contact connected to one end of the downward transducer. The second single-pole double-throw switch has its normally closed contact connected to the other end of the upward transducer and its normally open contact connected to the other end of the downward transducer. The third single-pole double-throw switch has its normally closed contact connected to one end of the downlink transducer and its normally open contact connected to one end of the uplink transducer. The fourth single-pole double-throw switch has its normally closed contact connected to the other end of the downlink transducer, its normally open contact connected to the other end of the uplink transducer, and its blade end connected to ground. The first single-pole single-throw switch has its blade end connected to one end of the uplink transducer, and its pull-in end connected to the other end of the uplink transducer via a resistor. The second single-pole single-throw switch has its blade end connected to one end of the downlink transducer, and its pull-in end connected to the other end of the downlink transducer via a resistor; The first single-pole double-throw switch, the second single-pole double-throw switch, the third single-pole double-throw switch, the fourth single-pole double-throw switch, the first single-pole single-throw switch, and the second single-pole single-throw switch are all controlled by the controller.

2. The circuit of claim 1, wherein, Also includes: A pulse generator, with its control terminal connected to the controller, is used to generate uplink and downlink pulse sequences under the control of the controller. The driver has its input terminal connected to the output terminal of the pulse generator, and its output terminal connected to the blade end of the first single-pole double-throw switch via a resistor. It is used to generate an in-phase pulse sequence with enhanced driving capability and a phase difference of 0 degrees with the uplink pulse sequence and the downlink pulse sequence. An inverter, with its input terminal connected to the output terminal of the pulse generator and its output terminal connected to the blade end of the second single-pole double-throw switch via a resistor, is used to generate an inverted pulse sequence with a phase difference of 180 degrees from the upward pulse sequence and the downward pulse sequence.

3. The circuit of claim 2, wherein, Also includes: An amplifier, with its input terminal connected to the blade end of the third single-pole double-throw switch via a resistor, is used to amplify the downlink ultrasonic signal relayed by the uplink transducer and the uplink ultrasonic signal relayed by the downlink transducer. The ADC acquisition module has its input terminal connected to the output terminal of the amplifier and its output terminal connected to the controller. It is used to perform analog-to-digital conversion on the signal output by the amplifier and send the digital signal to the controller.

4. A method of ultrasonic gas flow measurement in a circuit as claimed in any one of claims 1 to 3, characterized in that include: The controller controls generation of an uplink differential pulse sequence and sends the uplink differential pulse sequence to an uplink transducer; Upon receiving the uplink differential pulse sequence, the uplink transducer generates an uplink ultrasonic signal, and a downlink transducer receives and forwards the uplink ultrasonic signal; The forwarded uplink ultrasonic signal is amplified and analog-to-digital converted in sequence and then sent to the controller; The controller controls generation of a downlink differential pulse sequence and sends the downlink differential pulse sequence to the downlink transducer; Upon receiving the downlink differential pulse sequence, the downlink transducer generates a downlink ultrasonic signal, and the uplink transducer receives and forwards the downlink ultrasonic signal; The forwarded downlink ultrasonic signal is amplified and analog-to-digital converted in sequence and then sent to the controller; The controller calculates the time of flight based on the received downlink ultrasonic signal and uplink ultrasonic signal, thereby calculating the actual gas flow rate; The uplink transducer generates the uplink ultrasonic signal at a different time than the downlink transducer generates the downlink ultrasonic signal; The controller controls generation of an uplink differential pulse sequence and sends the uplink differential pulse sequence to an uplink transducer includes: The controller controls generation of an uplink differential pulse sequence and controls the first single-pole double-throw switch and the second single-pole double-throw switch to be normally closed and the first single-pole single-throw switch to be closed, thereby sending the uplink differential pulse sequence to the uplink transducer; Upon receiving the uplink differential pulse sequence, the uplink transducer generates an uplink ultrasonic signal, and a downlink transducer receives and forwards the uplink ultrasonic signal includes: Upon receiving the uplink differential pulse sequence, the uplink transducer generates an uplink ultrasonic signal, and a downlink transducer receives and forwards the uplink ultrasonic signal includes: The controller controls generation of a downlink differential pulse sequence and sends the downlink differential pulse sequence to the downlink transducer includes: The controller controls generation of a downlink differential pulse sequence and controls the third single-pole double-throw switch and the fourth single-pole double-throw switch to be normally open and the second single-pole single-throw switch to be closed, thereby sending the downlink differential pulse sequence to the downlink transducer; Upon receiving the downlink differential pulse sequence, the downlink transducer generates a downlink ultrasonic signal, and the uplink transducer receives and forwards the downlink ultrasonic signal includes: Upon receiving the downlink differential pulse sequence, the downlink transducer generates a downlink ultrasonic signal, and the uplink transducer receives and forwards the downlink ultrasonic signal includes:

5. The circuit of claim 4, wherein, The controller controls generation of an uplink differential pulse sequence includes: The controller controls a pulse generator to generate an uplink pulse sequence; The uplink pulse sequence is sent to a driver and an inverter, respectively, an uplink in-phase pulse sequence with enhanced driving capability and a phase difference of 0 degrees from the uplink pulse sequence is obtained at the output end of the driver, and an uplink inverted pulse sequence with a phase difference of 180 degrees from the uplink pulse sequence is obtained at the output end of the inverter; The uplink in-phase pulse sequence and the uplink inverted pulse sequence jointly form the uplink differential pulse sequence.

6. The circuit of claim 4, wherein, The controller controls the generation of a downlink differential pulse sequence, which comprises: The controller controls the pulse generator to generate a downlink pulse sequence; The downlink pulse sequence is sent to a driver and an inverter respectively, at the output end of the driver, a downlink in-phase pulse sequence with enhanced driving capability and a phase difference of 0 degrees with the downlink pulse sequence is obtained, at the output end of the inverter, a downlink inverted pulse sequence with a phase difference of 180 degrees with the downlink pulse sequence is obtained; The downlink in-phase pulse sequence and the uplink inverted pulse sequence jointly form the downlink differential pulse sequence.

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