Dual-frequency anti-interference ultrasonic water meter and metering method thereof

Abstract

The application discloses a dual-frequency anti-interference ultrasonic water meter and a metering method thereof, and relates to the technical field of fluid metering. A 500 kHz sound velocity reference channel is constructed by using a single transducer self-emission and self-reception mode: the sound path length under solidified pure water in a factory is calibrated, the current water quality sound velocity is calculated in real time under a zero flow state, the zero point offset of a 1 MHz main channel is dynamically corrected, and a high-precision temperature sensor is omitted. Meanwhile, online water quality diagnosis is realized by using a dual-frequency cooperation mechanism: turbidity is quantified by the amplitude ratio of 500 kHz and 1 MHz signals (based on the characteristics of high-frequency scattering sensitivity and low-frequency penetration), and bubbles are detected by the time domain fluctuation rate of the 1 MHz signal; according to the diagnosis result, the main channel flow metering precision is dynamically optimized by combining a sound velocity compensation model (the sound velocity is inversely proportional to the turbidity) and a hierarchical bubble compensation model (the sound velocity or flow is corrected according to the fluctuation rate). The method effectively overcomes medium interference, improves measurement reliability, and realizes real-time monitoring and reporting of basic water quality (turbidity and bubbles) at low cost.

Description

Technical Field

[0001] This invention relates to the field of fluid metering technology, and in particular to a dual-frequency anti-interference ultrasonic water meter and its metering method. Background Technology

[0002] As a core metering device in modern water supply networks, the accuracy of ultrasonic water meters directly affects the fairness of water resource management and trade settlement. Currently, mainstream reflective ultrasonic water meters generally employ single-frequency measurement technology (typically 1MHz), calculating flow velocity by measuring the time difference between upstream and downstream sound wave propagation. However, three key drawbacks exist in practical applications: First, the inherent asymmetry of the sound path in the reflective structure leads to zero-point drift, and traditional single-calibration at the factory cannot adapt to dynamic fluctuations in sound velocity caused by changes in water quality. Second, air bubbles and turbidity in the medium significantly alter the sound wave propagation characteristics, making it difficult for single-frequency systems to distinguish between bubble and turbidity interference, resulting in the failure of compensation strategies. Third, achieving dynamic calibration often requires the addition of high-precision temperature sensors, increasing costs and preventing the temperature model from accurately reflecting the direct impact of water quality changes on sound velocity. According to industry test data, under conditions of 5% air content and 50 NTU turbidity, the metering error of traditional single-frequency water meters can reach ±2.5%, far exceeding the ±1% requirement of the ISO 4064 standard.

[0003] In a typical scheme of "A Temperature Correction Method for Ultrasonic Water Meters Without Temperature Sensors" disclosed in Chinese Patent CN106885609A, the ultrasonic flight time corresponding to several temperatures is measured; it is determined whether different flight times are within a reasonable flight time; based on the sound velocity and flight time in water corresponding to several different temperatures, a scatter plot, piecewise correction curve, and curve equation are established for the reciprocal of the flight time and the sound velocity at each temperature; the average flight time is calculated; the measured sound velocity is calculated based on the curve equation; a fitting curve of the sound velocity and temperature of ultrasonic waves in water is established; and the corresponding fluid temperature is obtained. This invention can obtain accurate fluid temperature without a temperature sensor; it improves the accuracy of temperature compensation in ultrasonic water meters; it can accurately obtain the sound velocity at different temperatures in water, thereby improving the measurement accuracy of time-of-flight ultrasonic water meters; at the same time, it expands the compatibility of ultrasonic water meters with different ultrasonic flow sensors and reduces the hardware cost of ultrasonic water meters.

[0004] Existing technological shortcomings: 1. Zero drift problem: The sound path of the reflective ultrasonic water meter is asymmetrical (d1≠d2), and the traditional single zero flow calibration (factory calibration) cannot be dynamically compensated. In the past, dynamic compensation usually relied on real-time detection by temperature sensors and dynamic zero flow calibration through temperature model compensation algorithm. The indirect temperature model has insufficient accuracy and does not take into account the influence of water quality factors.

[0005] 2. Medium interference: Bubbles / turbidity change the sound propagation characteristics and introduce measurement errors. Single frequency cannot effectively analyze bubbles / turbidity, and therefore cannot provide a clear algorithm compensation strategy. 3. Disadvantages of dual-transducer through-beam sound velocity measurement: After one transducer transmits, the other transducer receives, resulting in a channel time difference and sound velocity measurement error; and due to the short sound path, it cannot be used for small-diameter ultrasonic water meters; the addition of a transducer increases the cost.

[0006] 4. Lack of basic water quality diagnostic functions: Professional turbidity sensors cannot be applied to residential applications due to cost issues.

[0007] Based on the shortcomings of existing technologies and comparative document analysis, the following technical bottlenecks urgently need to be overcome in this field: First, it is necessary to establish a real-time sound velocity measurement mechanism that does not rely on temperature sensors to fundamentally solve the zero-point drift problem of reflective water meters. Secondly, it is necessary to develop a dual-frequency collaborative diagnostic method to simultaneously distinguish between bubble and turbidity interference and quantify their degree of influence; Finally, a sound velocity-water quality coupling compensation model needs to be constructed to transform the diagnostic results into dynamically corrected parameters. The core of these problems lies in how to achieve this through innovative acoustic hardware architecture and collaborative signal processing algorithms. Achieving accurate measurement that adapts to different media while keeping costs under control is the key technical problem that this invention aims to solve. Summary of the Invention

[0008] In view of the aforementioned existing problems, the present invention is proposed.

[0009] Therefore, this invention provides a dual-frequency anti-interference ultrasonic water meter and its metering method to solve the problem of reflective ultrasonic water... The meter has problems with zero drift and measurement errors caused by water quality interference (bubbles, turbidity).

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a dual-frequency anti-interference ultrasonic water meter metering method, which includes the following steps: Step 1: Transmit ultrasonic waves through a 500kHz self-transmitting and self-receiving channel. After reflection by a mirror, the waves are received by the same transducer. Calculate the real-time sound velocity c based on the factory-calibrated fixed path length d3 and the time difference t under zero-current conditions. ture ; Step 2: In the 1MHz main flow channel, simultaneously collect the transit times T21 and T12 in the forward and reverse flow directions; Step 3: Calculate the turbidity value using the amplitude ratio of the dual-frequency received signals, and simultaneously extract the time-domain fluctuation rate of the 1MHz signal to characterize the bubble concentration; Step 4: Convert the real-time speed of sound c ture Turbidity value and bubble concentration are input into the dynamic compensation engine to generate the main channel sound velocity correction factor and flow compensation coefficient. Step 5: Calculate the actual flow rate based on the corrected sound velocity. When the bubble concentration exceeds the threshold, start the defoaming program and freeze the output.

[0011] As a preferred embodiment of the dual-frequency anti-interference ultrasonic water meter metering method of the present invention, wherein: the real-time sound velocity c ture The specific calculation process is as follows: When the flow rate is detected to be below 0.001 m³ / h for 5 consecutive seconds, it is determined to be in a zero flow state and the 500 kHz self-transmitting and self-receiving channel is activated. The embedded controller generates a 3-cycle sine pulse with a pulse width of 6 μs to excite transducer B to emit ultrasonic waves, which are focused by the parabolic reflector and return to the same transducer. The receiver uses a cross-correlation algorithm to accurately capture the reflected wave peak and measures the time difference t from transmission to reception with a resolution of 10 ns. Call the factory calibration parameter d3 pre-stored in the EEPROM. Where d3 is the 500kHz self-transmitting and self-receiving path length. The standard speed of sound for pure water at 20°C. The time difference between transmitting and receiving the reflected signal is used as the calibration environment, which is 20℃ pure water, with an accuracy of ±0.01mm. This is achieved through the arithmetic unit executing c... ture = d3 / t to calculate the real-time speed of sound; Simultaneously collect temperature sensor data mounted on the back of transducer B. If the current water temperature deviates from the calibrated temperature by more than ±2℃, activate the sound velocity-temperature compensation model c. temp = 1402.5 + 4.5T 0.04T², where T is the temperature in Celsius, and c is initially corrected; The corrected sound velocity value is compared with the current 1MHz main channel bidirectional time difference ΔT. zero The data are stored together in a circular buffer. When the buffer is full of 30 sets of data, a sound speed-time difference curve is generated based on least squares fitting to predict the parameters of the next cycle.

[0012] As a preferred embodiment of the dual-frequency anti-interference ultrasonic water meter metering method of the present invention, the specific implementation process of calculating the turbidity value NTU is as follows: The dual-channel synchronous ADC simultaneously acquires 500kHz and 1MHz received signals at a sampling rate of 5MSPS. A fourth-order Butterworth digital bandpass filter with a bandwidth of 490~510kHz is used for the 500kHz channel, and an equivalent filter with a bandwidth of 990~1010kHz is used for the 1MHz channel. The envelope curve is extracted by applying a 16th-order FIR Hilbert transformer to the filtered signal, and the envelope peak values ​​of the last 100 sampling points of the two channels are detected inside the FPGA. Calculate the dual-frequency amplitude ratio R = (1MHz peak envelope) / (500kHz peak envelope + 10) -6 Avoid division by zero errors; Call the pre-calibrated turbidity conversion parameters a, b, and d (obtained through laboratory calibration of 0~100 NTU standard turbidity solutions), and execute NTU = a×e in the floating-point arithmetic unit. b×R + d exponent calculation; The results of every 10 measurements are smoothed using median filtering to eliminate sudden noise interference.

[0013] As a preferred embodiment of the dual-frequency anti-interference ultrasonic water meter metering method of the present invention, the specific implementation process for characterizing the bubble concentration is as follows: For the time-domain signal after filtering the 1MHz channel, sliding segmentation is performed with a window length of 500 sampling points and a step size of 250 points; Within each window, the arithmetic mean μ and standard deviation σ of the signal amplitude are calculated in real time, and the volatility F = σ / (μ + 10) is calculated using a hardware divider. -6 ); Three levels of bubble concentration determination thresholds are set: when F < 0.1, it is marked as level 1 (low bubble influence); when 0.1 ≤ F < 0.3, it is marked as level 2 (medium bubble influence); and when F ≥ 0.3, it is marked as level 3 (high bubble influence). The mechanical defoaming device is immediately activated upon encountering a level 3 bubble state, while the flow output is frozen and a 10-second countdown is activated. Volatility is continuously monitored during the freeze period. If the F value does not drop below 0.3 within 10 seconds, the freeze period is extended until the target is met.

[0014] As a preferred embodiment of the dual-frequency anti-interference ultrasonic water meter metering method of the present invention, the specific implementation process of the dynamic compensation engine is as follows: Receive the NTU value output from the turbidity calculation module, and calculate the turbidity compensation coefficient K through polynomial interpolation. turb = 1 2.5×10 -5 ×NTU corrects the main channel sound velocity to c turb = c ture ×K turb ; Combining the volatility F output by the bubble detection module with the grading label, if it is a level 1 bubble, then the secondary correction coefficient K is calculated. bubble = 1 0.03×F, output the final speed of sound c corr= c turb ×K bubble ; If it is a level 2 bubble, the speed of sound remains constant, and the original flow rate Q is compensated for. corr = Q / (1 + 0.5 × F); The compensated flow data is input into a second-order Kalman filter with process noise variance set to 0.001 and observation noise variance set to 0.1, and the output is the smoothed final flow value. When a level 3 bubble is detected, the Kalman filter input is frozen and the last valid output value is retained.

[0015] Secondly, the present invention provides a dual-frequency anti-interference ultrasonic water meter system, comprising, The measurement tube section integrates a parabolic reflector and a plane reflector group, in which the parabolic reflector and the 500kHz transducer form a self-emitting and self-receiving reference channel with a fixed sound path length of d3. The plane mirror assembly and two 1MHz transducers form the main flow measurement channel of the V-shaped acoustic path; The signal processing unit includes a dual-channel time-to-digital converter (TDC) and a programmable gain amplifier (PGA). The dynamic compensation processor has a built-in three-dimensional compensation lookup table; The mechanical defoaming module is integrated at the front end of the water inlet, including a 30° spiral guide vane and a piezoelectric ceramic cavitation generator; The included angle of the mirrors of the planar reflector group is 110°, which makes the sound path length of the main channel reach 2.8 times the pipe diameter.

[0016] As a preferred embodiment of the dual-frequency anti-interference ultrasonic water meter system described in this invention, the specific structure of the self-transmitting and self-receiving reference channel is as follows: The focal length of the parabolic mirror is designed to be 8.0±0.1mm, and the surface roughness Ra≤0.4μm. The 500kHz transducer is installed precisely at the focal point of the parabolic surface, with its central axis forming an angle ≤0.5° with the optical axis of the reflecting mirror. An acoustic insulating sponge with a thickness of 3mm and an opening ratio of ≥90% is placed between the transducer and the reflector to absorb side-scattered waves. The calibration of d3 was performed using the laser interferometric positioning method. The measurement was repeated 100 times in a pure water environment at 20±0.1℃, and the average value was taken. The calibration results were written into the read-only memory.

[0017] In a preferred embodiment of the dual-frequency anti-interference ultrasonic water meter system described in this invention, the hardware configuration of the signal processing unit is as follows: Time measurement uses a TDC-GP22 chip with a time resolution of 55 ps; The programmable gain amplifier has 32 gain settings from 0 to 60 dB, and the automatic gain control (AGC) circuit dynamically adjusts the gain according to the signal amplitude. The bandpass filter uses a switched capacitor filter MAX297, and its center frequency can be digitally adjusted via the SPI interface. The Hilbert converter is implemented on an Altera Cyclone IV FPGA and uses a 16-stage pipeline architecture to process 5MSPS data streams.

[0018] As a preferred embodiment of the dual-frequency anti-interference ultrasonic water meter system of the present invention, the working method of the dynamic compensation processor is as follows: It has 512 built-in three-dimensional compensation parameters, including temperature (20~30℃, step 0.2℃), turbidity (0~100NTU, step 5NTU), and bubble fluctuation rate (0~0.4, step 0.02). Parameter interpolation is achieved using a radial basis function (RBF) neural network. The hidden layer of the network contains 48 neurons, and the activation function is a Gaussian function. ; The system automatically performs a parameter self-check every 24 hours. When it detects 10 consecutive compensation deviations exceeding ±0.5%, a calibration alarm is triggered.

[0019] As a preferred embodiment of the dual-frequency anti-interference ultrasonic water meter system of the present invention, the control logic of the mechanical defoaming module is as follows: When the bubble classification is marked as level 2, the spiral guide vane is activated to form a swirling flow field. At the same time, the piezoelectric ceramic cavitation generator is driven at a frequency of 40kHz to generate cavitation bubble groups with a diameter of 50~100μm, which are continuously operated for 30±5 seconds. When marked as Level 3, it continues to run until volatility F < 0.25. If the target is not met within 300 seconds, it switches to pulse mode, working for 10 seconds and pausing for 5 seconds. The inlet is equipped with a conical flow stabilizer, with its opening ratio decreasing from 80% to 40% along the water flow direction, which is used to break up large air bubbles.

[0020] Thirdly, the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein when the computer program is executed by the processor, it implements any step of the dual-frequency anti-interference ultrasonic water meter metering method as described in the first aspect of the present invention.

[0021] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, it implements any step of the dual-frequency anti-interference ultrasonic water meter metering method as described in the first aspect of the present invention.

[0022] The beneficial effects of this invention are: First, a real-time sound velocity benchmark for current water quality is provided. The construction mechanism of this benchmark is groundbreaking at the physical level: by embedding a factory-calibrated fixed sound path length d3 (accuracy ±0.01mm) into a 500kHz self-transmitting and self-receiving channel, and combining it with the real-time ultrasonic round-trip time t measured under zero-flow conditions, the sound velocity value c is directly calculated. ture = d3 / t, this sound velocity value accurately reflects the comprehensive physical characteristics of the current water quality (including the effects of temperature, turbidity, and dissolved substances), with an accuracy of 0.03% and completely independent of external sensors; this benchmark serves as the core basis for dynamic zero-point calibration, successfully eliminating the inherent zero-point drift caused by the asymmetry of sound path in reflective water meters. Laboratory verification shows that within the water temperature range of 10~30℃ and the turbidity range of 0~50NTU, the zero-point offset is stably suppressed within 0.001m³ / h, which is 85% more accurate than the traditional temperature compensation model.

[0023] Secondly, online water quality diagnosis is achieved through dual-frequency collaboration. This mechanism creatively utilizes the differences in the physical properties of sound waves: 500kHz low-frequency waves have strong penetrability to suspended particles, while 1MHz high-frequency waves are highly sensitive to scattering. Through dual-channel signal processing, the amplitude ratio is calculated in real time to accurately quantify turbidity (error ≤ ±3NTU). Simultaneously, the time-domain fluctuation rate F = σ / μ of the 1MHz signal is extracted to characterize the bubble concentration (grading accuracy 98.7%). The diagnostic results directly drive the compensation engine to perform main channel metering optimization. Turbidity compensation adopts an inverse sound velocity model, while bubble compensation dynamically switches between sound velocity correction and flow rate correction according to the grading strategy. Even under harsh conditions with 30% gas content and 100NTU turbidity, it still maintains a metering accuracy of ±1.5%, which is 40% more adaptable than the international standard ISO 4064.

[0024] More importantly, it enables real-time reporting of water quality at low cost. This advantage stems from the deep reuse of hardware architecture: the sound velocity reference channel and the dual-frequency diagnostic module share the same set of transducers and processor resources, and can output three types of parameters, namely flow rate, turbidity, and bubble concentration, through only algorithm upgrades. The data is transmitted back to the water platform via the NB-IoT module at an ultra-low load of 0.1KB every 15 minutes. The daily transmission volume of household water meters only increases by 0.5KB, but a water quality monitoring network covering the end of the pipe network is built. This allows water companies to grasp turbidity anomalies of more than 20 NTU and air blockage risks with fluctuation rates of more than 0.25 for the first time on a large scale. Compared with the deployment of professional sensor solutions, it reduces operation and maintenance costs by 92% and provides direct data support for pipeline corrosion early warning and secondary pollution prevention and control.

[0025] The above three points form a closed loop of "measurement-diagnosis-reporting", which reduces the measurement error under all operating conditions to within ±1% with only a 7% increase in hardware costs. At the same time, it upgrades a single water meter into a water quality monitoring node for the pipeline network, promoting the strategic transformation of smart water management from flow measurement to multi-parameter perception. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart of a dual-frequency anti-interference ultrasonic water meter metering method in Example 1.

[0028] Figure 2 This is an overall structural diagram of a dual-frequency anti-interference ultrasonic water meter system in Example 2.

[0029] Figure 3 This is a schematic diagram of the overall principle topology of a dual-frequency anti-interference ultrasonic water meter system in Example 4.

[0030] Figure 4 This is a dual-frequency collaborative architecture of a dual-frequency anti-interference ultrasonic water meter system in Example 4.

[0031] Figure 2 The components are: 1. Measurement chamber; 2. Casing pipe; 3. Ultrasonic transducer C; 4. Ultrasonic transducer D; 5. Reflector A; 6. Ultrasonic transducer B; 7. Reflector B. Detailed Implementation

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0034] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0035] Example 1, referring to Figure 1 This is the first embodiment of the present invention, which provides a dual-frequency anti-interference ultrasonic water meter metering method, including the following steps: Step 1: Transmit ultrasonic waves through a 500kHz self-transmitting and self-receiving channel. After reflection by a mirror, the waves are received by the same transducer. Calculate the real-time sound velocity c based on the factory-calibrated fixed path length d3 and the time difference t under zero-current conditions. ture ; Step 2: In the 1MHz main flow channel, simultaneously collect the transit times T21 and T12 in the forward and reverse flow directions; Step 3: Calculate the turbidity value using the amplitude ratio of the dual-frequency received signals, and simultaneously extract the time-domain fluctuation rate of the 1MHz signal to characterize the bubble concentration; Step 4: Convert the real-time speed of sound c ture Turbidity value and bubble concentration are input into the dynamic compensation engine to generate the main channel sound velocity correction factor and flow compensation coefficient. Step 5: Calculate the actual flow rate based on the corrected sound velocity. When the bubble concentration exceeds the threshold, start the defoaming program and freeze the output.

[0036] Real-time speed of sound c ture The specific calculation process is as follows: When the flow rate is detected to be below 0.001 m³ / h for 5 consecutive seconds, it is determined to be in a zero flow state and the 500 kHz self-transmitting and self-receiving channel is activated. The embedded controller generates a 3-cycle sine pulse with a pulse width of 6 μs to excite transducer B to emit ultrasonic waves, which are focused by the parabolic reflector and return to the same transducer. The receiver uses a cross-correlation algorithm to accurately capture the reflected wave peak and measures the time difference t from transmission to reception with a resolution of 10 ns. Call the factory calibration parameter d3 pre-stored in the EEPROM. Where d3 is the 500kHz self-transmitting and self-receiving path length. The standard speed of sound for pure water at 20°C. The time difference between transmitting and receiving the reflected signal is used as the calibration environment, which is 20℃ pure water, with an accuracy of ±0.01mm. This is achieved through the arithmetic unit executing c... ture = d3 / t to calculate the real-time speed of sound; Simultaneously collect temperature sensor data mounted on the back of transducer B. If the current water temperature deviates from the calibrated temperature by more than ±2℃, activate the sound velocity-temperature compensation model c. temp = 1402.5 + 4.5T 0.04T², where T is the temperature in Celsius, and c is initially corrected; The corrected sound velocity value is compared with the current 1MHz main channel bidirectional time difference ΔT. zero The data are stored together in a circular buffer. When the buffer is full of 30 sets of data, a sound speed-time difference curve is generated based on least squares fitting to predict the parameters of the next cycle.

[0037] The specific implementation process for calculating the turbidity value NTU is as follows: The dual-channel synchronous ADC simultaneously acquires 500kHz and 1MHz received signals at a sampling rate of 5MSPS. A fourth-order Butterworth digital bandpass filter with a bandwidth of 490~510kHz is used for the 500kHz channel, and an equivalent filter with a bandwidth of 990~1010kHz is used for the 1MHz channel. The envelope curve is extracted by applying a 16th-order FIR Hilbert transformer to the filtered signal, and the envelope peak values ​​of the last 100 sampling points of the two channels are detected inside the FPGA. Calculate the dual-frequency amplitude ratio R = (1MHz peak envelope) / (500kHz peak envelope + 10) -6 Avoid division by zero errors; Call the pre-calibrated turbidity conversion parameters a, b, and d (obtained through laboratory calibration of 0~100 NTU standard turbidity solutions), and execute NTU = a×e in the floating-point arithmetic unit. b×R + d exponent calculation; The results of every 10 measurements are smoothed using median filtering to eliminate sudden noise interference.

[0038] The specific implementation process for characterizing bubble concentration is as follows: For the time-domain signal after filtering the 1MHz channel, sliding segmentation is performed with a window length of 500 sampling points and a step size of 250 points; Within each window, the arithmetic mean μ and standard deviation σ of the signal amplitude are calculated in real time, and the volatility F = σ / (μ + 10) is calculated using a hardware divider. -6 ); Three levels of bubble concentration determination thresholds are set: when F < 0.1, it is marked as level 1 (low bubble influence); when 0.1 ≤ F < 0.3, it is marked as level 2 (medium bubble influence); and when F ≥ 0.3, it is marked as level 3 (high bubble influence). The mechanical defoaming device is immediately activated upon encountering a level 3 bubble state, while the flow output is frozen and a 10-second countdown is activated. Volatility is continuously monitored during the freeze period. If the F value does not drop below 0.3 within 10 seconds, the freeze period is extended until the target is met.

[0039] The specific implementation process of the dynamic compensation engine is as follows: Receive the NTU value output from the turbidity calculation module, and calculate the turbidity compensation coefficient K through polynomial interpolation. turb = 1 2.5×10 -5 ×NTU corrects the main channel sound velocity to c turb = c ture ×K turb ; Combining the volatility F output by the bubble detection module with the grading label, if it is a level 1 bubble, then the secondary correction coefficient K is calculated. bubble = 1 0.03×F, output the final speed of sound c corr = c turb ×K bubble ; If it is a level 2 bubble, the speed of sound remains constant, and the original flow rate Q is compensated for. corr = Q / (1 + 0.5 × F); The compensated flow data is input into a second-order Kalman filter with process noise variance set to 0.001 and observation noise variance set to 0.1, and the output is the smoothed final flow value. When a level 3 bubble is detected, the Kalman filter input is frozen and the last valid output value is retained.

[0040] Example 2, refer to Figure 2 This is the second embodiment of the present invention, which provides a dual-frequency anti-interference ultrasonic water meter system, comprising: The measurement tube section integrates a parabolic reflector and a plane reflector group, in which the parabolic reflector and the 500kHz transducer form a self-emitting and self-receiving reference channel with a fixed sound path length of d3. The plane mirror assembly and two 1MHz transducers form the main flow measurement channel of the V-shaped acoustic path; The signal processing unit includes a dual-channel time-to-digital converter (TDC) and a programmable gain amplifier (PGA). The dynamic compensation processor has a built-in three-dimensional compensation lookup table; The mechanical defoaming module is integrated at the front end of the water inlet, including a 30° spiral guide vane and a piezoelectric ceramic cavitation generator; The included angle of the mirrors in the plane mirror assembly is 110°, which makes the sound path length of the main channel reach 2.8 times the pipe diameter.

[0041] The specific structure of the self-transmitting and self-receiving reference channel is as follows: The focal length of the parabolic mirror is designed to be 8.0±0.1mm, and the surface roughness Ra≤0.4μm. The 500kHz transducer is installed precisely at the focal point of the parabolic surface, with its central axis forming an angle ≤0.5° with the optical axis of the reflecting mirror. An acoustic insulating sponge with a thickness of 3mm and an opening ratio of ≥90% is placed between the transducer and the reflector to absorb side-scattered waves. The calibration of d3 was performed using the laser interferometric positioning method. The measurement was repeated 100 times in a pure water environment at 20±0.1℃, and the average value was taken. The calibration results were written into the read-only memory.

[0042] The hardware configuration of the signal processing unit is as follows: Time measurement uses a TDC-GP22 chip with a time resolution of 55 ps; The programmable gain amplifier has 32 gain settings from 0 to 60 dB, and the automatic gain control (AGC) circuit dynamically adjusts the gain according to the signal amplitude. The bandpass filter uses a switched capacitor filter MAX297, and its center frequency can be digitally adjusted via the SPI interface. The Hilbert converter is implemented on an Altera Cyclone IV FPGA and uses a 16-stage pipeline architecture to process 5MSPS data streams.

[0043] The working method of the dynamic compensation processor is as follows: It has 512 built-in three-dimensional compensation parameters, including temperature (20~30℃, step 0.2℃), turbidity (0~100NTU, step 5NTU), and bubble fluctuation rate (0~0.4, step 0.02). Parameter interpolation is achieved using a radial basis function (RBF) neural network. The hidden layer of the network contains 48 neurons, and the activation function is a Gaussian function. ; The system automatically performs a parameter self-check every 24 hours. When it detects 10 consecutive compensation deviations exceeding ±0.5%, it triggers a calibration alarm.

[0044] The control logic of the mechanical defoaming module is as follows: When the bubble classification is marked as level 2, the spiral guide vane is activated to form a swirling flow field. At the same time, the piezoelectric ceramic cavitation generator is driven at a frequency of 40kHz to generate cavitation bubble groups with a diameter of 50~100μm, which are continuously operated for 30±5 seconds. When marked as Level 3, it continues to run until volatility F < 0.25. If the target is not met within 300 seconds, it switches to pulse mode, working for 10 seconds and pausing for 5 seconds. The inlet is equipped with a conical flow stabilizer, with its opening ratio decreasing from 80% to 40% along the water flow direction, which is used to break up large air bubbles.

[0045] Example 3, referring to Figure 1, is the third embodiment of the present invention. The specific workflow and implementation method of the dual-frequency anti-interference ultrasonic water meter metering method in this embodiment are as follows: When water flows through the measuring pipe section, the system first detects the instantaneous flow rate using a flow sensor. If the flow rate is below 0.001 m³ / h for 5 consecutive seconds, it is determined to be in a zero-flow state and the sound velocity reference measurement is activated: a 500 kHz transducer emits a 3-cycle sinusoidal pulse with a pulse width of 6 μs. The ultrasonic wave is focused by a parabolic reflector and propagates along a fixed sound path d3, returning to the same transducer. The TDC chip accurately captures the time difference t between transmission and reception with a resolution of 55 ps, calls the factory calibration value d3 (calibrated by laser interferometry in pure water at 20°C) pre-stored in the read-only memory, and executes the calculation through the floating-point arithmetic unit.ture = d3 / t calculates the real-time velocity of sound; synchronously collects data from the temperature sensor mounted on the back of the transducer; when the water temperature deviates from the calibration temperature by more than ±2℃, a compensation model c is used. temp = 1402.5 + 4.5T The sound velocity is initially corrected by 0.04T², and the correction result is stored in a circular buffer.

[0046] Simultaneously with the start of the sound velocity measurement, the 1MHz main flow channel operates synchronously: two 1MHz transducers emit ultrasonic waves through a V-shaped reflector array with a 110° angle. High-speed timers record the transit times T21 in the downstream direction and T12 in the upstream direction, respectively, achieving a measurement accuracy of 0.1ns. The dual-frequency received signals undergo synchronous processing: the 500kHz channel uses a 490~510kHz bandpass filter to eliminate environmental noise, and the 1MHz channel uses a 990~1010kHz filter to optimize the signal-to-noise ratio. The filtered signals are then input to a 16th-order Hilbert transformer based on an FPGA to extract the envelope. The envelope data from the last 100 sampling points of each channel are extracted to calculate the 500kHz peak value. 500 and 1MHz peak 1m ; using the amplitude ratio formula R = Peak 1m / (Peak 500 +10 -6 Calculate the dual-frequency amplitude ratio and input it into the exponential model NTU = a·e b·R +d Output turbidity value (coefficients a, b, d are calibrated with standard turbidity solution); Simultaneously, bubble detection is performed on the 1MHz time-domain signal: the signal is segmented with a window length of 500 sampling points and a step size of 250 points, and the standard deviation σ and mean μ of the signal amplitude in each window are calculated in real time. The volatility F = σ / (μ + 10) is obtained through a hardware divider. -6 Bubble concentration is graded according to threshold (F<0.1 is grade 1, 0.1≤F<0.3 is grade 2, F≥0.3 is grade 3).

[0047] The dynamic compensation engine receives real-time sound speed c ture After marking the turbidity NTU and bubble classification, a three-stage processing is initiated: first, sound velocity correction is performed based on the turbidity value. turb = c×(1 2.5×10 -5 ×NTU); secondly, select the compensation mode based on bubble grading—if it is a level 1 bubble, then correct the sound velocity c a second time. corr = c turb ×(1 0.03×F), if it is a level 2 bubble, then keep the speed of sound constant and perform Q on the original flow rate Q. corr= Q / (1 + 0.5×F); Finally, the compensated parameters are input into a second-order Kalman filter with a preset process noise variance of 0.001 and an observation noise variance of 0.1, and the output is a smooth flow value. When a level 3 bubble is detected, the flow output is immediately frozen and the defoaming program is activated: the 30° spiral guide vane at the inlet is started to form a swirling flow field, and at the same time, the piezoelectric ceramic cavitation generator is driven at a frequency of 40kHz to generate cavitation bubble groups of 50~100μm, which continues to run until the fluctuation rate F<0.25 (maximum 300 seconds, after which a pulse mode of 10 seconds of operation and 5 seconds of rest is switched). All diagnostic data (velocity of sound c, turbidity NTU, bubble level) are packaged into a 0.1KB data packet every 15 minutes and uploaded to the water platform through the NB-IoT module. During this period, the system continuously monitors the changes in water quality parameters and dynamically updates the compensation parameters, forming a "measurement-diagnosis-compensation-control" closed loop.

[0048] This process maintains a metering accuracy of ±1.5% even under extreme operating conditions (30% gas content + 100 NTU turbidity), with a daily power consumption increase of no more than 0.5 Wh. Furthermore, it absorbs scattered interference through acoustic isolation sponge (open area ≥90%) to ensure signal purity, fundamentally solving the problems of zero drift and media interference in reflective water meters.

[0049] Example 4, referring to Figures 2 to 4, is the fourth embodiment of the present invention. The working process and specific implementation method of a dual-frequency anti-interference ultrasonic water meter system in this embodiment are as follows: When water flows into the measuring chamber 1 inside the casing pipe 2 from the inlet, it first flows through a conical flow stabilizer (not shown in the figure, the opening ratio decreases from 80% to 40% along the water flow direction) to break up air bubbles with a diameter greater than 1mm. The water then flows through a V-shaped main measuring channel composed of ultrasonic transducers C3 and D4 and a reflector A5, and a sound velocity reference channel composed of ultrasonic transducers B6 and a parabolic reflector B7. After the system starts, it performs parallel dual-channel measurements: in the 500kHz sound velocity reference channel, transducer B6 emits a 3-cycle sinusoidal pulse (pulse width 6μs). The ultrasonic waves are focused by the parabolic reflector B7 with a focal length of 8.0mm to form a sound beam with a diameter ≤3mm. The reflected wave returns to the same transducer along a fixed sound path d3. The d3 value calibrated by laser interferometry (average of 100 measurements in a 20℃ pure water environment, accuracy ±0.01mm) is pre-stored in a read-only memory. The TDC chip measures the transit time t with a resolution of 0.1ns, and the data is transmitted through the C-channel. ture = d3 / t calculates the real-time sound velocity. When the temperature sensor mounted on the back of transducer B detects a water temperature deviation of ±2℃ from the calibration value, the sound velocity-temperature compensation model is automatically activated. temp = 1402.5 + 4.5T A correction of 0.04T² is applied.

[0050] During the simultaneous 1MHz main flow measurement, transducers C3 and D4 emit ultrasonic waves through a V-shaped reflector group 5 with a 110° angle (see reflector arrangement). Figure 2 An extended acoustic path 2.8 times the pipe diameter was constructed. A high-speed timer recorded the transit time T21 in the downstream direction and T12 in the upstream direction (accuracy 0.1 ns). The dual-frequency received signals underwent synchronous processing: the 500kHz signal was filtered through a 490~510kHz bandpass filter to eliminate ambient noise, and the 1MHz signal was filtered through a 990~1010kHz filter to optimize the signal-to-noise ratio. The filtered data was then input to a 16th-order Hilbert transformer based on FPGA to extract the envelope, and the peak envelope was calculated from the last 100 sampling points of both channels. 500 and Peak 1m The water quality diagnostic module calculates the dual-frequency amplitude ratio R = Peak in real time. 1m / (Peak 500 +10 -6 Substituting this into the laboratory-calibrated exponential model NTU = a·e b·R +d (a, b, d are calibrated using 0~100 NTU standard turbidity solution) outputs turbidity values; simultaneously, bubble detection is performed on the 1MHz signal: using 500 sampling points as the window and 250 points as the step size, the signal is segmented in real time, and the standard deviation σ and mean μ of the amplitude of each window are calculated. The volatility F = σ / (μ + 10) is obtained through a hardware divider. -6 Bubble concentration is graded according to threshold (F<0.1 is grade 1, 0.1≤F<0.3 is grade 2, F≥0.3 is grade 3).

[0051] The dynamic compensation engine receives the velocity of sound (c), turbidity NTU, and bubble classification markers, and then performs three levels of optimization: First, based on turbidity (c)... turb = c×(1 2.5×10 -5 ×NTU) corrects the velocity of sound; secondly, selects the compensation mode according to the bubble level—for level 1 bubbles, c is used. corr = c turb ×(1 0.03×F) Secondary correction of sound velocity, Q is applied to the original flow rate Q when there is a second-stage bubble. corr= Q / (1 + 0.5×F) correction; finally, the parameters are input into a second-order Kalman filter with a preset process noise variance of 0.001 and an observation noise variance of 0.1 to output a smoothed flow value. When a level 3 bubble is detected, the flow output is immediately frozen and the mechanical defoaming module is activated: the 30° spiral guide vane at the inlet is activated to form a swirling flow field, and at the same time, the piezoelectric ceramic cavitation generator is driven at a frequency of 40kHz to generate 50~100μm cavitation bubble groups, which continue to run until the fluctuation rate F<0.25 (if it does not meet the standard after more than 300 seconds, it switches to a pulse mode of working for 10 seconds and pausing for 5 seconds). All diagnostic data (sound velocity, turbidity, bubble level) are packaged into a 0.1KB data packet every 15 minutes and uploaded to the water management platform via NB-IoT or RS485.

[0052] The power system employs dual backup of batteries and supercapacitors (see...) Figure 3 Topology: Under normal operation, the system is powered by a supercapacitor. In the event of a power outage, it automatically switches to battery power and enters a low-power mode, ensuring no data loss for 72 hours. Throughout the process, the acoustic isolation sponge (3mm thick, porosity ≥90%) placed between the transducer and the reflector effectively absorbs side-scattered waves, while the parabolic reflector's surface roughness Ra≤0.4μm ensures accurate sound wave focusing. Under extreme conditions (30% gas content + 100NTU turbidity), the system's measurement error is ≤±1.5%, and the daily power consumption increment is controlled within 0.5Wh, achieving a closed-loop process of "measurement-diagnosis-compensation-reporting".

[0053] This embodiment also provides a computer device applicable to dual-frequency anti-interference ultrasonic water meters and their metering methods, including: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to realize the dual-frequency anti-interference ultrasonic water meter and its metering method as proposed in the above embodiment. The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0054] This embodiment also provides a storage medium storing a computer program. When executed by a processor, the program implements the dual-frequency anti-interference ultrasonic water meter and its metering method as proposed in the above embodiments. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0055] In summary, a real-time sound velocity benchmark for current water quality is provided. The construction mechanism of this benchmark is groundbreaking at the physical level: by embedding a factory-calibrated fixed sound path length d3 (accuracy ±0.01mm) into a 500kHz self-transmitting and self-receiving channel, and combining it with the real-time ultrasonic round-trip time t measured under zero-flow conditions, the sound velocity value c is directly calculated. ture = d3 / t, this sound velocity value accurately reflects the comprehensive physical characteristics of the current water quality (including the effects of temperature, turbidity, and dissolved substances), with an accuracy of 0.03% and completely independent of external sensors; this benchmark serves as the core basis for dynamic zero-point calibration, successfully eliminating the inherent zero-point drift caused by the asymmetry of sound path in reflective water meters. Laboratory verification shows that within the water temperature range of 10~30℃ and the turbidity range of 0~50NTU, the zero-point offset is stably suppressed within 0.001m³ / h, which is 85% more accurate than the traditional temperature compensation model.

[0056] Secondly, online water quality diagnosis is achieved through dual-frequency collaboration. This mechanism creatively utilizes the differences in the physical properties of sound waves: 500kHz low-frequency waves have strong penetrability to suspended particles, while 1MHz high-frequency waves are highly sensitive to scattering. Through dual-channel signal processing, the amplitude ratio is calculated in real time to accurately quantify turbidity (error ≤ ±3NTU). Simultaneously, the time-domain fluctuation rate F = σ / μ of the 1MHz signal is extracted to characterize the bubble concentration (grading accuracy 98.7%). The diagnostic results directly drive the compensation engine to perform main channel metering optimization. Turbidity compensation adopts an inverse sound velocity model, while bubble compensation dynamically switches between sound velocity correction and flow rate correction according to the grading strategy. Even under harsh conditions with 30% gas content and 100NTU turbidity, it still maintains a metering accuracy of ±1.5%, which is 40% more adaptable than the international standard ISO 4064.

[0057] More importantly, it enables real-time reporting of water quality at low cost. This advantage stems from the deep reuse of hardware architecture: the sound velocity reference channel and the dual-frequency diagnostic module share the same set of transducers and processor resources, and can output three types of parameters, namely flow rate, turbidity, and bubble concentration, through only algorithm upgrades. The data is transmitted back to the water platform via the NB-IoT module at an ultra-low load of 0.1KB every 15 minutes. The daily transmission volume of household water meters only increases by 0.5KB, but a water quality monitoring network covering the end of the pipe network is built. This allows water companies to grasp turbidity anomalies of more than 20 NTU and air blockage risks with fluctuation rates of more than 0.25 for the first time on a large scale. Compared with the deployment of professional sensor solutions, it reduces operation and maintenance costs by 92% and provides direct data support for pipeline corrosion early warning and secondary pollution prevention and control.

[0058] The above three points form a closed loop of "measurement-diagnosis-reporting", which reduces the measurement error under all operating conditions to within ±1% with only a 7% increase in hardware costs. At the same time, it upgrades a single water meter into a water quality monitoring node for the pipeline network, promoting the strategic transformation of smart water management from flow measurement to multi-parameter perception.

[0059] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A dual-frequency anti-interference ultrasonic water meter metering method, characterized in that, Includes the following steps: Step 1: Transmit ultrasonic waves through a 500kHz self-transmitting and self-receiving channel. After reflection by a mirror, the waves are received by the same transducer. Calculate the real-time sound velocity c based on the factory-calibrated fixed path length d3 and the time difference t under zero-current conditions. ture ; Step 2: In the 1MHz main flow channel, simultaneously collect the transit times T21 and T12 in the forward and reverse flow directions; Step 3: Calculate the turbidity value NTU using the amplitude ratio R of the dual-frequency received signals, and simultaneously extract the time-domain fluctuation rate F of the 1MHz signal to characterize the bubble concentration; call the pre-calibrated turbidity conversion parameters a, b, and d, and obtain them through laboratory calibration of 0~100NTU standard turbidity solutions, and execute NTU = a×e in the floating-point arithmetic unit. b×R + d exponent calculation; Three levels of bubble concentration determination thresholds are set: when F < 0.1, it is marked as level 1, with low bubble influence; when 0.1 ≤ F < 0.3, it is marked as level 2, with medium bubble influence; and when F ≥ 0.3, it is marked as level 3, with high bubble influence. Step 4: Convert the real-time speed of sound c ture Turbidity value and bubble concentration are input into the dynamic compensation engine to generate the main channel sound velocity correction factor and flow compensation coefficient. Receive the NTU value output from the turbidity calculation module and calculate the turbidity compensation coefficient K through polynomial interpolation. turb = 1 2.5×10 -5 ×NTU corrects the main channel sound velocity to c turb =c ture ×K turb ; Combining the volatility F output by the bubble detection module with the grading label, if it is a level 1 bubble, then the secondary correction coefficient K is calculated. bubble = 1 0.03×F, output the final speed of sound c corr = c turb ×K bubble ; If it is a level 2 bubble, the speed of sound remains constant, and the original flow rate Q is compensated to obtain the compensated flow rate Q. corr = Q / (1 + 0.5 × F); The compensated flow data is input into a second-order Kalman filter with process noise variance set to 0.001 and observation noise variance set to 0.1, and the output is the smoothed final flow value. When a level 3 bubble is detected, freeze the Kalman filter input and retain the last valid output value; Step 5: Calculate the actual flow rate based on the corrected sound velocity, and freeze the output when the bubble concentration exceeds the threshold.

2. The dual-frequency anti-interference ultrasonic water meter metering method as described in claim 1, characterized in that: The real-time speed of sound c ture The specific calculation process is as follows: When the flow rate is detected to be below 0.001 m³ / h for 5 consecutive seconds, it is determined to be in a zero flow state and the 500 kHz self-transmitting and self-receiving channel is activated. The embedded controller generates a 3-cycle sine pulse with a pulse width of 6 μs to excite transducer B to emit ultrasonic waves, which are focused by the parabolic reflector and return to the same transducer. The receiver uses a cross-correlation algorithm to accurately capture the reflected wave peak and measures the time difference t from transmission to reception with a resolution of 10 ns. Call the factory calibration parameter d3 pre-stored in the EEPROM. Where d3 is the 500kHz self-transmitting and self-receiving path length. The standard speed of sound for pure water at 20°C. The time difference between transmitting and receiving the reflected signal is used as the calibration environment, which is 20℃ pure water, with an accuracy of ±0.01mm. This is achieved through the arithmetic unit executing c... ture = d3 / t to calculate the real-time speed of sound; The corrected sound velocity value is compared with the current 1MHz main channel bidirectional time difference ΔT. zero The data are stored together in a circular buffer. When the buffer is full of 30 sets of data, a sound speed-time difference curve is generated based on least squares fitting to predict the parameters of the next cycle.

3. The dual-frequency anti-interference ultrasonic water meter metering method as described in claim 2, characterized in that: The specific implementation process for calculating the turbidity value NTU is as follows: The dual-channel synchronous ADC simultaneously acquires 500kHz and 1MHz received signals at a sampling rate of 5MSPS. A fourth-order Butterworth digital bandpass filter with a bandwidth of 490~510kHz is used for the 500kHz channel, and an equivalent filter with a bandwidth of 990~1010kHz is used for the 1MHz channel. The envelope curve is extracted by applying a 16th-order FIR Hilbert transformer to the filtered signal, and the envelope peak values ​​of the last 100 sampling points of the two channels are detected inside the FPGA. Calculate the amplitude ratio R of the dual-frequency received signal: R = (1MHz peak envelope) / (500kHz peak envelope + 10) -6 Avoid division by zero errors; The results of every 10 measurements are smoothed using median filtering to eliminate sudden noise interference.

4. The dual-frequency anti-interference ultrasonic water meter metering method as described in claim 3, characterized in that: The specific implementation process for characterizing bubble concentration is as follows: For the time-domain signal after filtering the 1MHz channel, sliding segmentation is performed with a window length of 500 sampling points and a step size of 250 points; Within each window, the arithmetic mean μ and standard deviation σ of the signal amplitude are calculated in real time, and the volatility F = σ / (μ + 10) is calculated using a hardware divider. -6 ); The mechanical defoaming device is immediately activated upon encountering a level 3 bubble state, while the flow output is frozen and a 10-second countdown is activated. Volatility is continuously monitored during the freeze period. If the F value does not drop below 0.3 within 10 seconds, the freeze period is extended until the target is met.

5. A dual-frequency anti-interference ultrasonic water meter system, based on any one of claims 1 to 4. The method for measuring water using a frequency-resistant, interference-resistant ultrasonic water meter is characterized by, include: The measurement tube section integrates a parabolic reflector and a plane reflector group, in which the parabolic reflector and the 500kHz transducer form a self-emitting and self-receiving reference channel with a fixed sound path length of d3. The plane mirror assembly and two 1MHz transducers form the main flow measurement channel of the V-shaped acoustic path; The signal processing unit includes a dual-channel time-to-digital converter (TDC) and a programmable gain amplifier (PGA). The dynamic compensation processor has a built-in three-dimensional compensation lookup table; The mechanical defoaming module is integrated at the front end of the water inlet, including a 30° spiral guide vane and a piezoelectric ceramic cavitation generator; The included angle of the mirrors of the planar reflector group is 110°, which makes the sound path length of the main channel reach 2.8 times the pipe diameter.

6. The dual-frequency anti-interference ultrasonic water meter system as described in claim 5, characterized in that: The The specific structure of the self-transmitting and self-receiving reference channel is as follows: The focal length of the parabolic mirror is designed to be 8.0±0.1mm, and the surface roughness Ra≤0.4μm. The 500kHz transducer is installed precisely at the focal point of the parabolic surface, with its central axis forming an angle ≤0.5° with the optical axis of the reflecting mirror. An acoustic insulating sponge with a thickness of 3mm and an opening ratio of ≥90% is placed between the transducer and the reflector to absorb side-scattered waves. The calibration of d3 was performed using the laser interferometric positioning method. The measurement was repeated 100 times in a pure water environment at 20±0.1℃, and the average value was taken. The calibration results were written into the read-only memory.

7. The dual-frequency anti-interference ultrasonic water meter system as described in claim 6, characterized in that: The The hardware configuration of the signal processing unit is as follows: Time measurement uses a TDC-GP22 chip with a time resolution of 55 ps; The programmable gain amplifier has 32 gain settings from 0 to 60 dB, and the automatic gain control (AGC) circuit dynamically adjusts the gain according to the signal amplitude. The bandpass filter uses a switched capacitor filter MAX297, and its center frequency can be digitally adjusted via the SPI interface. The Hilbert converter is implemented on an Altera Cyclone IV FPGA and uses a 16-stage pipeline architecture to process 5MSPS data streams.

8. The dual-frequency anti-interference ultrasonic water meter system as described in claim 7, characterized in that: The The working method of the dynamic compensation processor is as follows: It has 512 built-in three-dimensional compensation parameters, including temperature (20~30℃, step 0.2℃), turbidity (0~100NTU, step 5NTU), and bubble fluctuation rate (0~0.4, step 0.02). Parameter interpolation is achieved using a radial basis function (RBF) neural network. The hidden layer of the network contains 48 neurons, and the activation function is a Gaussian function. ; The system automatically performs a parameter self-check every 24 hours. When it detects 10 consecutive compensation deviations exceeding ±0.5%, a calibration alarm is triggered.

9. The dual-frequency anti-interference ultrasonic water meter system as described in claim 8, characterized in that: Place The control logic of the mechanical defoaming module is as follows: When the bubble classification is marked as level 2, the spiral guide vane is activated to form a swirling flow field. At the same time, the piezoelectric ceramic cavitation generator is driven at a frequency of 40kHz to generate cavitation bubble groups with a diameter of 50~100μm, which are continuously operated for 30±5 seconds. When marked as Level 3, it continues to run until volatility F < 0.

25. If the target is not met within 300 seconds, it switches to pulse mode, working for 10 seconds and pausing for 5 seconds. The inlet is equipped with a conical flow stabilizer, with its opening ratio decreasing from 80% to 40% along the water flow direction, which is used to break up large air bubbles.

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