An automatic gain processing device for ultrasonic gas meter metering signals

Abstract

This invention discloses an automatic gain control (AGA) processing device for ultrasonic gas meter metering signals. The power supply interface is connected to a power management module, which in turn is connected to an input signal matching module, an AGA processing module, and an output signal matching module. The signal input interface is connected to the input signal matching module, which in turn is connected to the AGA processing module. The AGA processing module is connected to the output signal matching module, which is connected to both a differential signal output interface and a single-ended signal output interface. This device is used to filter, buffer, perform automatic gain control of the amplitude of the input ultrasonic echo signal, and convert the differential signal for output. This invention can maintain the amplitude of the ultrasonic echo signal within a relatively stable and reasonable range under different gas compositions, different flow channel structures, and different temperatures, providing a strong guarantee for the accurate measurement of the ultrasonic signal propagation time during subsequent co-current and counter-current flow.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic gas meter technology, and specifically to an automatic gain processing device for ultrasonic gas meter metering signals. Background Technology

[0002] Ultrasonic gas meters, with their advantages of small size, wide measuring range, high accuracy, and long lifespan, have become the mainstream gas metering device on the market after ordinary diaphragm gas meters, IC card gas meters, wired gas meters, and wireless remote transmission gas meters.

[0003] Currently, the time-of-flight method is the most widely used measurement method in ultrasonic gas metering technology. Specifically, it calculates the gas velocity by using the difference in ultrasonic signal propagation time during upstream and downstream flow, and then combines this with the flow channel dimensions to calculate the gas flow rate. Therefore, the accurate measurement of ultrasonic signal propagation time during upstream and downstream flow becomes a key factor restricting the metering accuracy of ultrasonic gas meters.

[0004] The amplitude of ultrasonic signals attenuates significantly during transmission, resulting in the received ultrasonic echo signal having an amplitude of only a few millivolts, which is highly detrimental to the detection of ultrasonic echo signals. Furthermore, factors such as different gas compositions, improper flow channel design, and temperature variations can also greatly affect the amplitude of ultrasonic echo signals, severely impacting the accuracy of measuring ultrasonic signal propagation time in both downstream and upstream flow conditions.

[0005] Existing ultrasonic gas meters primarily employ the following three methods to process the amplitude of ultrasonic echo signals:

[0006] 1. For example Figure 1 The fixed-gain amplification method shown utilizes an operational amplifier to build a fixed-gain amplification circuit to amplify the amplitude of the ultrasonic echo signal at a fixed gain. When parameters such as gas composition, flow channel structure design, and temperature remain constant, the amplitude of the ultrasonic echo signal tends to stabilize, and it can barely function normally under these conditions. However, using a fixed-gain amplification circuit to amplify the amplitude of the ultrasonic echo signal by a fixed factor will cause measurement failure because the amplification factor cannot be adaptive.

[0007] 2. For example Figure 2The multi-level adjustable gain amplification method shown first involves a feedback circuit measuring the amplitude of the output signal. Based on the measurement result, the amplification factor of the operational amplifier in the amplifier circuit is controlled by adjusting the input resistor of an analog switch or digital potentiometer, thus forming a multi-level adjustable gain amplification circuit for the ultrasonic echo signal amplitude. However, due to the limited range of amplification factor adjustments, a matching test is required before normal operation. It can function normally even with slight changes in parameters such as gas composition, flow channel design, and temperature. However, this multi-level adjustable gain amplification circuit suffers from limited amplification factor adjustment range, low precision, the need for a matching test before normal operation, poor anti-interference capability, and lack of versatility.

[0008] 3. For example Figure 3 The feedback-based automatic gain amplification method shown first measures the amplitude of the output signal, then feeds the measurement result back to the reference voltage pin of the programmable operational amplifier in the amplifier circuit to control the amplification factor of the programmable operational amplifier, thus forming a feedback-based automatic gain amplification circuit to automatically amplify the amplitude of the ultrasonic echo signal. Since it requires an external feedback circuit to function properly, it can operate normally under certain conditions of changes in parameters such as gas composition, flow channel structure design, and temperature, provided the external feedback circuit's performance is stable. While the feedback-based automatic gain control circuit can theoretically achieve adaptive amplification factor, it requires an external feedback circuit, resulting in signal delay, low real-time performance, and excessively complex circuit construction, often requiring multiple cascaded stages, leading to high power consumption and lacking versatility.

[0009] Therefore, how to keep the amplitude of the received ultrasonic signal stable has become an urgent problem to be solved. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides an automatic gain processing device for ultrasonic gas meter metering signals.

[0011] This invention discloses an automatic gain processing device for ultrasonic gas meter metering signals, comprising: a power supply interface, a signal input interface, a differential signal output interface, a single-ended signal output interface, a power management module, an input signal matching module, an automatic gain processing module, and an output signal matching module;

[0012] The power supply interface is connected to the power management module, and the power management module is connected to the input signal matching module, the automatic gain control module, and the output signal matching module respectively.

[0013] The signal input interface is connected to the input signal matching module, the input signal matching module is connected to the automatic gain control module, the automatic gain control module is connected to the output signal matching module, and the output signal matching module is connected to the differential signal output interface and the single-ended signal output interface, respectively.

[0014] As a further improvement of the present invention

[0015] The input signal matching module is used to filter and buffer the ultrasonic echo signal input from the signal input interface to obtain a first signal;

[0016] The automatic gain control module is used to perform automatic gain control on the first signal to obtain a differential signal;

[0017] The output signal matching module is used to filter the differential signal and input the filtered differential signal to the differential signal output interface; at the same time, it converts the filtered differential signal into a single-ended signal and inputs the single-ended signal to the single-ended signal output interface.

[0018] As a further improvement of the present invention, the power supply interface provides a DC voltage of 3V.

[0019] As a further improvement of the present invention, the power management module consists of a buck module and a negative voltage conversion module connected together. The buck module is a low-dropout linear regulator with reverse current protection and enable function, and the negative voltage conversion module is a switched capacitor voltage converter.

[0020] As a further improvement of the present invention, the signal input interface is used to input an ultrasonic echo signal to be processed at a frequency of 200kHz.

[0021] As a further improvement of the present invention, the input signal matching module includes an active high-pass filter composed of capacitors, resistors and operational amplifiers.

[0022] As a further improvement of the present invention, the signal automatic gain processing module includes an automatic gain amplifier and is built using an integrated circuit chip, eliminating the need for additional external feedback circuitry.

[0023] As a further improvement of the present invention, the output signal matching module includes a high-pass filter and a differential-to-single-ended operational amplifier connected together, the differential signal output interface is connected between the high-pass filter and the differential-to-single-ended operational amplifier, and the single-ended signal output interface is connected to the output terminal of the differential-to-single-ended operational amplifier.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The device of the present invention has an automatic gain control function. With the help of this device, the amplitude of the ultrasonic echo signal can be maintained within a relatively stable and reasonable range under different gas compositions, different flow channel structures and different temperatures. This provides a strong guarantee for the accurate measurement of the ultrasonic signal propagation time in subsequent co-current and counter-current flow, and improves the measurement accuracy of ultrasonic signal propagation time.

[0026] 2. The circuit structure of the device of the present invention is simple and does not require multi-stage cascading. In particular, the automatic gain processing module is built using an integrated circuit chip solution, which eliminates the need for additional external feedback circuits. It has high reliability and low power consumption, making it very suitable for battery-powered scenarios. At the same time, it has an enable control pin, which provides an interface for further control of power consumption and has strong expandability.

[0027] 3. The device of the present invention has both differential and single-ended signal output interfaces, which are highly expandable and can be used in multiple scenarios. Attached Figure Description

[0028] Figure 1 This is a schematic diagram illustrating the principle of the existing fixed-gain amplification method.

[0029] Figure 2 This is a schematic diagram illustrating the principle of an existing multi-level adjustable gain amplification method;

[0030] Figure 3 This is a schematic diagram illustrating the principle of feedback automatic gain amplification.

[0031] Figure 4 This is a schematic diagram of the structure of an automatic gain processing device for ultrasonic gas meter metering signals disclosed in one embodiment of the present invention;

[0032] Figure 5 This is a framework diagram of an automatic gain processing device for ultrasonic gas meter metering signals disclosed in one embodiment of the present invention;

[0033] Figure 6 This is a circuit diagram of an automatic gain processing device for ultrasonic gas meter metering signals, disclosed in one embodiment of the present invention.

[0034] In the picture:

[0035] 1. Power supply interface; 2. Signal input interface; 3. Differential signal output interface; 4. Single-ended signal output interface; 5. Power management module; 6. Input signal matching module; 7. Automatic gain control module; 8. Output signal matching module; 9. Housing. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The present invention will now be described in further detail with reference to the accompanying drawings:

[0038] like Figure 4 , 5 As shown, the present invention provides an automatic gain control (AGC) device for ultrasonic gas meter metering signals, comprising: a power supply interface 1, a signal input interface 2, a differential signal output interface 3, a single-ended signal output interface 4, a power management module 5, an input signal matching module 6, an automatic gain control (AGC) module 7, and an output signal matching module 8; wherein, the power supply interface 1, the signal input interface 2, the differential signal output interface 3, and the single-ended signal output interface 4 are mounted on a housing 9, and the power management module 5, the input signal matching module 6, the automatic gain control (AGC) module 7, and the output signal matching module 8 are mounted inside the housing 9.

[0039] The connection relationships of the various modules or interfaces in this invention are as follows:

[0040] The power supply interface 1 of the present invention is connected to the power management module 5, and the power management module 5 is connected to the input signal matching module 6, the automatic gain control module 7, and the output signal matching module 8 respectively; the signal input interface 2 is connected to the input signal matching module 6, the input signal matching module 6 is connected to the automatic gain control module 7, the automatic gain control module 7 is connected to the output signal matching module 8, and the output signal matching module 8 is connected to the differential signal output interface 3 and the single-ended signal output interface 4 respectively.

[0041] The functions of each module or interface in this invention are as follows:

[0042] Signal input interface 2 is used to input the ultrasonic echo signal to be processed;

[0043] Power management module 5 is used to generate the operating voltage for input signal matching module 6, signal automatic gain processing module 7, and output signal matching module 8;

[0044] The input signal matching module 6 is used to filter and buffer the ultrasonic echo signal input from the signal input interface 2.

[0045] The automatic gain control module 7 is used to perform automatic gain control on the signal input from the input signal matching module 6 to ensure amplitude stability and output a differential signal with stable amplitude.

[0046] The output signal matching module 8 is used to filter the signal input from the automatic gain control module 7, and input the filtered differential signal to the differential signal output interface 3 for output; at the same time, it converts the filtered differential signal into a single-ended signal and inputs the single-ended signal to the single-ended signal output interface 4 for output.

[0047] like Figure 6 As shown, the circuit structure of each module or interface of this invention is as follows:

[0048] Power supply interface 1 is used to provide system power to the automatic gain processing device for the ultrasonic gas meter metering signal. The power supply voltage is DC 3V.

[0049] Power management module 5 includes a step-down module consisting of U1 and a negative voltage converter module consisting of U2. U1 is an ultra-low IQ (quiescent current) low-dropout linear regulator with reverse current protection and enable function, used to convert DC 3V voltage to DC +2.5V voltage. Input and output capacitors C1, C2, and C3 are used to improve transient response, reduce ripple, and improve PSRR (Power Supply Rejection Ratio); stable and type-regulating X7R ceramic capacitors are recommended. U2 is a switched capacitor voltage converter used to convert DC +2.5V voltage to DC -2.5V voltage. Capacitors C4 and C7 are charge pump capacitors with a capacitance of 10μF, and capacitors C5 and C6 are used to improve transient response, reduce ripple, and improve PSRR.

[0050] Signal input interface 2 is used to input an ultrasonic echo signal with a frequency of 200kHz to be processed.

[0051] The input signal matching module 6 is used to filter and buffer the 200kHz ultrasonic echo signal input from the signal input interface. Since the ultrasonic echo signal amplitude is relatively low, only a few millivolts, and contains DC and AC interference components, this invention uses capacitor C24 and resistor R15 to form a high-pass filter. Resistor R14 provides a path for discharging the DC signal in the ultrasonic echo signal. Utilizing the characteristics of an ideal operational amplifier—infinite input resistance and infinitesimal output resistance—operational amplifier U4, along with capacitor C24 and resistor R15, forms an active high-pass filter to filter and buffer the ultrasonic echo signal. Impedance matching can be achieved by adjusting the value of resistor R5.

[0052] The automatic gain control (AGC) module 7 is used to perform automatic gain control on the signal input from the input signal matching module to ensure amplitude stability, keeping the amplitude of the ultrasonic echo signal within a relatively stable and reasonable range. It is particularly noteworthy that the AGC module involved in this invention uses an integrated circuit chip, eliminating the need for additional external feedback circuitry. U3 is a low-noise, low-power variable gain amplifier compatible with single-ended and differential inputs, featuring precise gain. U3 is powered by +3V and integrates a current output RMS detector, allowing it to be configured as an AGC amplifier for automatic gain control. Pins INPR and INMR, and pins INPD and INMD, represent two sets of signal input ports. The difference is that INPR and INMR have integrated 1K fixed-value resistors, while the INPD and INMD input ports allow users to adjust the gain range by configuring external resistor values ​​according to different application scenarios. The ultrasonic echo signal input mode can be flexibly adjusted by selectively soldering resistors R7, R11, R8, and R12. Resistor R13 is a reserved adjustment resistor used to control the on / off state of the preceding and following stages. Capacitors C21 and C26, along with resistors R9 and R10, form a high-pass filter to block DC or low-frequency components in the ultrasonic echo signal. Pin VREF is an internal 1.5V reference voltage source. The AGC circuit adjusts the voltage at the drive gain control input pin GAIN based on the voltage difference between pin VAGC and pin VREF. Capacitor C25 is used to adjust the response time of the AGC circuit. The final target RMS voltage is the absolute value of the voltage difference between pin VAGC and pin VREF, i.e., V. OUT_RMS =|V AGC -1.5|, Pin MODE is the gain slope control pin. Since the AGC circuit uses negative feedback, Pin MODE needs to be grounded. Pin OFSN is the offset calibration pin. Capacitor C17 and the internal resistor of U3 form a high-pass filter for offset calibration. Pins OUTP and OPTM are the positive and negative output pins of the differential signal. FBKP and FBKM are the positive and negative feedback nodes of the differential signal. Capacitors C18 and C20, together with the feedback resistor inside U3, form a low-pass filter to reduce high-frequency noise in the output signal and improve the output signal quality.

[0053] The output signal matching module 8 is used to filter the signal input from the automatic gain control module, convert the differential signal into a single-ended signal, and output the processed differential and single-ended signals through the differential signal output interface 3 and the single-ended signal output interface 4, respectively. Capacitor C11 and resistor R3, and capacitor C13 and resistor R6 form two sets of high-pass filters to further reduce high-frequency noise in the output signal. U5 is a differential-to-single-ended operational amplifier used to convert the differential signal output from the automatic gain control module into a single-ended signal.

[0054] The advantages of this invention are:

[0055] 1. The device of the present invention has an automatic gain control function. With the help of this device, the amplitude of the ultrasonic echo signal can be maintained within a relatively stable and reasonable range under different gas compositions, different flow channel structures and different temperatures. This provides a strong guarantee for the accurate measurement of the ultrasonic signal propagation time in subsequent co-current and counter-current flow, and improves the measurement accuracy of ultrasonic signal propagation time.

[0056] 2. The circuit structure of the device of the present invention is simple and does not require multi-stage cascading. In particular, the automatic gain processing module is built using an integrated circuit chip solution, which eliminates the need for additional external feedback circuits. It has high reliability and low power consumption, making it very suitable for battery-powered scenarios. At the same time, it has an enable control pin, which provides an interface for further control of power consumption and has strong expandability.

[0057] 3. The device of the present invention has both differential and single-ended signal output interfaces, which are highly expandable and can realize multi-scenario applications; for example, it can be connected to a differential analog-to-digital converter for high-precision waveform detection, or it can be connected to an ultrasonic time metering chip for ultrasonic time-of-flight measurement via single-ended output.

[0058] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An automatic gain processing device for ultrasonic gas meter metering signals, characterized in that, include: Power supply interface, signal input interface, differential signal output interface, single-ended signal output interface, power management module, input signal matching module, signal automatic gain processing module, and output signal matching module; The power supply interface is connected to the power management module, and the power management module is connected to the input signal matching module, the automatic gain control module, and the output signal matching module, respectively. The signal input interface is connected to the input signal matching module, the input signal matching module is connected to the signal automatic gain processing module, the signal automatic gain processing module is connected to the output signal matching module, and the output signal matching module is connected to the differential signal output interface and the single-ended signal output interface respectively. in, The input signal matching module is used to filter and buffer the ultrasonic echo signal input from the signal input interface to obtain a first signal; The automatic gain control (AGC) module is used to perform amplitude automatic gain control on the first signal to obtain a differential signal. The AGC module includes a variable gain amplifier with an integrated current output root mean square detector to configure it as an AGC amplifier for automatic gain control. Selective soldering of resistors R7, R11, R8, and R12 allows for flexible adjustment of the ultrasonic echo signal input mode. Resistor R13 is a reserved adjustment resistor used to control the on / off state of the preceding and following stages. Capacitors C21 and C26, along with resistors R9 and R10, form a high-pass filter to block DC or low-frequency components in the ultrasonic echo signal. Capacitor C25 is used to adjust the response time of the AGC circuit. Capacitors C18 and C20, together with the feedback resistor inside U3, form a low-pass filter to reduce high-frequency noise in the output signal. The output signal matching module is used to filter the differential signal and input the filtered differential signal to the differential signal output interface; at the same time, it converts the filtered differential signal into a single-ended signal and inputs the single-ended signal to the single-ended signal output interface.

2. The automatic gain processing device for ultrasonic gas meter metering signals as described in claim 1, characterized in that, The power supply interface provides a DC 3V supply voltage.

3. The automatic gain processing device for ultrasonic gas meter metering signals as described in claim 1, characterized in that, The power management module consists of a connected step-down module and a negative voltage conversion module. The step-down module is a low-dropout linear regulator with reverse current protection and enable function, and the negative voltage conversion module is a switched capacitor voltage converter.

4. The automatic gain processing device for ultrasonic gas meter metering signals as described in claim 1, characterized in that, The signal input interface is used to input ultrasonic echo signals with a frequency of 200kHz to be processed.

5. The automatic gain processing device for ultrasonic gas meter metering signals as described in claim 1, characterized in that, The input signal matching module includes an active high-pass filter composed of capacitors, resistors, and operational amplifiers.

6. The automatic gain processing device for ultrasonic gas meter metering signals as described in claim 1, characterized in that, The automatic gain control (AGC) module includes an automatic gain amplifier and is built using an integrated circuit chip, eliminating the need for an external feedback circuit.

7. The automatic gain processing device for ultrasonic gas meter metering signals as described in claim 1, characterized in that, The output signal matching module includes a high-pass filter and a differential-to-single-ended operational amplifier connected together. The differential signal output interface is connected between the high-pass filter and the differential-to-single-ended operational amplifier, and the single-ended signal output interface is connected to the output terminal of the differential-to-single-ended operational amplifier.

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