Ultrasonic flowmeter and gas meter trigger wave automatic adjusting method

Abstract

The invention discloses an ultrasonic flowmeter and gas meter trigger wave automatic adjustment method, which comprises the following steps: acquiring a trigger voltage threshold Vthi, and setting a signal-to-noise ratio lower limit SNRmini; receiving wave signals are obtained and subjected to gain processing, the amplitude of the processed receiving wave signals is determined, and the signal-to-noise ratio (SNR) is calculated in combination with the noise amplitude; the SNR is compared with the SNRmini, and a final trigger voltage threshold value is determined; when SNR is smaller than SNRmin3, detection is stopped, and detection is restarted based on a preset interval time threshold value; when the amplitude of the processed received wave signal is higher than a final trigger voltage threshold, outputting a square wave signal; and in the process of outputting the square wave signal, continuously acquiring the received wave signal and performing gain processing, and recalculating the gain value for the gain processing. According to the invention, the anti-interference performance of the ultrasonic flowmeter can be improved, so that the ultrasonic flowmeter can normally operate in a relatively complex measurement occasion, and the metering accuracy is ensured.

Description

Technical Field

[0001] The present application relates to the technical field of ultrasonic flowmeters, and more specifically, to an ultrasonic flowmeter and a method for automatically adjusting trigger waves of a gas meter. Background Art

[0002] Ultrasonic flowmeters (gas meters) are widely used for gas and liquid metering due to their advantages, such as extremely low starting flow rates, wide rangeability, and lack of mechanical rotating parts. However, due to power constraints in many applications, most ultrasonic flowmeters are battery-powered. To reduce power consumption and extend battery life, most employ a time-difference method based on zero-crossing detection. Due to the varying media types, media conditions, and environmental conditions, particularly low-pressure natural gas, conventional battery-powered ultrasonic flowmeters often experience significant measurement errors or even malfunction, leading to frequent metering trade disputes. Therefore, most gas ultrasonic flowmeters on the market that utilize zero-crossing detection employ various techniques to overcome the problem of missing measurements due to wave skipping. These techniques all revolve around adjusting the trigger voltage threshold for first-wave detection based on the amplitude of the received signal, or determining whether the received signal meets measurement requirements.

[0003] At present, most products on the market use battery-powered ultrasonic flow meters. In order to reduce power consumption and realize battery power supply, the zero-crossing detection method is generally used. However, the current zero-crossing detection ultrasonic flow meters generally use fixed first wave detection, which has the advantage of good zero point stability when the signal-to-noise ratio meets the requirements; but when the medium pressure is low, the environmental interference is large, etc., the signal-to-noise ratio of the amplified received wave signal is reduced, which will lead to the error in the recognition of the first wave, resulting in large measurement errors or even failure to operate normally; for this reason, different manufacturers have adopted a variety of methods and technologies, some of which automatically adjust the first wave trigger voltage threshold according to the amplitude of the detected received wave signal; Some use the peak position of the received wave to identify whether there is a forward or backward jump and make corrections. Some use two trigger voltage thresholds. When the first wave cannot be triggered due to low signal amplitude, the second wave triggers the second threshold for detection. Some use the first wave trigger voltage threshold and the second trigger voltage threshold to obtain the ultrasonic transmission time through the first wave trigger. After the first wave triggers several waveform cycles, the second trigger threshold is activated. Another comparator outputs several pulses for pulse width comparison. By measuring the pulse width and calculating the change in the pulse width, the change in the received wave is judged, and corrections and adjustments are made. These are effective only when the signal-to-noise ratio basically meets the measurement conditions. However, when the signal-to-noise ratio of the received wave is so low that the noise amplitude in the received wave approaches the amplitude of the first wave signal or even exceeds the tolerance of the first wave signal amplitude, the above measures will not work.

[0004] Therefore, the prior art has defects and is in urgent need of improvement. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide an ultrasonic flow meter and a gas meter trigger wave automatic adjustment method, which automatically adjusts the amplitude of the received wave signal by detecting the AGC circuit, and detects the signal amplitude and signal-to-noise ratio at the same time. When the signal amplitude reaches the design requirement range, the corresponding trigger voltage threshold for the first wave trigger, the second wave trigger or the third wave detection is automatically selected according to the level of the signal-to-noise ratio, and the signal-to-noise ratio lower limit corresponding to the trigger voltage threshold for the first wave trigger, the second wave trigger or the third wave detection is set, that is, when the signal-to-noise ratio is higher than the signal-to-noise ratio lower limit required for normal detection, the trigger voltage threshold is automatically selected. The system uses first-wave detection; when the signal-to-noise ratio falls below the lower limit of the signal-to-noise ratio required for normal detection, the second-wave trigger detection is initiated; when the signal-to-noise ratio falls below the lower limit of the signal-to-noise ratio required for the second-wave trigger detection, the system switches to third-wave detection; if the signal-to-noise ratio drops further, the system stops detecting to avoid mismeasurement; after stopping detection, the system starts the detection process at the set time interval, adjusts the received wave signal, and detects the signal-to-noise ratio. If the signal-to-noise ratio rises above the minimum signal-to-noise ratio lower limit required for the first-wave, first-wave, or second-wave detection wave trigger, the system switches to the appropriate first-wave, first-wave, or second-wave detection. This technology can improve the anti-interference performance of ultrasonic flowmeters, enabling them to operate normally in more complex measurement situations and ensuring accurate measurement.

[0006] A first aspect of the present invention provides an ultrasonic flowmeter and a gas meter trigger wave automatic adjustment method, comprising:

[0007] Get the trigger voltage threshold Vth preset by the system i ; The trigger voltage threshold includes the first wave trigger voltage threshold Vth1, the second wave trigger voltage threshold Vth2 and the third wave trigger voltage threshold Vth3;

[0008] Based on the trigger voltage threshold Vth i Set the signal-to-noise ratio lower limit SNRmin i The signal-to-noise ratio lower limit includes the first wave trigger detection signal-to-noise ratio lower limit SNRmin1, the second wave trigger detection signal-to-noise ratio lower limit SNRmin2 and the third wave detection signal-to-noise ratio lower limit SNRmin3;

[0009] Obtaining received wave signals;

[0010] performing gain processing on the received wave signal to determine the amplitude of the processed received wave signal;

[0011] Calculating a signal-to-noise ratio (SNR) based on the processed received wave signal amplitude and noise amplitude;

[0012] The signal-to-noise ratio SNR is compared with the signal-to-noise ratio lower limit SNRmin i Make a comparison and determine the final trigger voltage threshold;

[0013] When SNR < SNRmin3, stop the detection and restart the detection based on the preset interval time threshold;

[0014] comparing the processed received wave signal with the final trigger voltage threshold, and outputting a square wave signal when the amplitude of the processed received wave signal is higher than the final trigger voltage threshold;

[0015] During the process of outputting the square wave signal, the received wave signal is continuously acquired and gain processing is performed. When the amplitude of the processed received wave signal is not within the preset target amplitude range, the gain value for gain processing is recalculated.

[0016] In this solution, the trigger voltage threshold Vth i Set the signal-to-noise ratio lower limit SNRmin i The specific method is:

[0017] ;

[0018] ;

[0019] Where i represents the i-th wave trigger, S represents the amplitude of the received wave signal after processing, and N i Indicates the noise amplitude triggered by the i-th wave, Vth i is the i-th wave trigger voltage threshold, and ΔV is the preset voltage adjustment parameter.

[0020] In this solution, performing gain processing on the received wave signal to determine the processed received wave signal includes:

[0021] performing gain processing on the received wave signal based on an initial gain value or a gain value detected in a previous round;

[0022] Determine whether the amplitude of the processed received wave signal is within a preset target amplitude range;

[0023] If so, the amplitude of the received wave signal after processing is output;

[0024] If not, the gain value is recalculated, and gain processing is performed again on the received wave signal based on the recalculated gain value to obtain the amplitude of the processed received wave signal.

[0025] In this solution, the signal-to-noise ratio SNR is compared with the signal-to-noise ratio lower limit SNRmin. i Compare and determine the final trigger voltage threshold, including:

[0026] When SNR>SNRmin1, the first-wave trigger voltage threshold Vth1 is determined as the final trigger voltage threshold;

[0027] When SNRmin2≤SNR<SNRmin1, the second wave trigger voltage threshold Vth2 is determined as the final trigger voltage threshold;

[0028] When SNRmin3≤SNR<SNRmin2, the third wave trigger voltage threshold Vth3 is determined as the final trigger voltage threshold.

[0029] This plan also includes:

[0030] When SNR < SNRmin3, stop the test and record the cumulative stop time;

[0031] When the accumulated stop time is greater than the preset interval time threshold, the detection is restarted.

[0032] This plan also includes:

[0033] When the final trigger voltage threshold is the second wave trigger voltage threshold Vth2 or the third wave trigger voltage threshold Vth3, the forward and reverse sound wave transmission times corresponding to the square wave signal are corrected.

[0034] This plan also includes:

[0035] When SNR<SNRmin3, calculating the maximum peak-to-peak rate of change within the first preset time interval based on the historical received wave signals within the first preset time interval;

[0036] When the maximum peak-to-peak change rate within the first preset time interval is greater than a preset change rate threshold, entering a waveform freezing mode;

[0037] Recording the freeze mode duration based on the waveform freeze mode start time, and continuing to collect the received wave signal;

[0038] calculating a first peak-to-peak rate of change based on the received wave signal within a second preset time interval;

[0039] When the peak value change rate of the first wave peak is within a preset change rate threshold range, the waveform freezing model termination condition is met and the waveform freezing mode is exited;

[0040] When the duration of the freezing mode is greater than a preset time threshold, if the waveform freezing model termination condition is still not met, the detection is stopped.

[0041] This plan also includes:

[0042] When entering the waveform freeze mode, the historical received wave signal within the first preset time interval is input into the preset waveform change prediction model, and a predicted waveform change curve is output; the predicted waveform change curve includes a first predicted waveform change curve corresponding to the duration of the waveform freeze mode and a second predicted waveform change curve after exiting the waveform freeze mode;

[0043] After exiting the waveform freeze mode, the waveform correction scheme is determined based on the signal-to-noise ratio and waveform matching of the first valid received wave signal;

[0044] Based on the waveform correction scheme, waveform correction is performed on the predicted received wave signal corresponding to the predicted waveform change curve and the effective received wave signal after exiting the waveform freezing mode.

[0045] In this solution, the method for performing waveform correction on the effective received wave signal after exiting the waveform freeze mode based on the waveform correction solution is specifically as follows:

[0046] Determine the first adjustment weight k of the first effective received wave signal according to the signal-to-noise ratio of the first effective received wave signal a(t) ;

[0047] Determine the adjustment time interval according to the waveform matching degree of the first valid received wave signal;

[0048] A first adjustment weight k based on the adjustment time interval and the first effective received wave signal a(t) The first adjustment weight of the subsequent valid received wave signal is set to determine the first adjustment weight k of the valid received wave signal at the detection time t+m a(t+m) ;

[0049] Based on the detection time T, the first adjustment weight k of the effective received wave signal is a(T) Determine the second adjustment weight k of the predicted received wave signal corresponding to the detection time b(T) ;k b(T) =1-k a(T) ;

[0050] Based on the detection time T, a weighted calculation is performed on the signal peak value of the effective received wave signal and the signal peak value of the corresponding predicted received wave signal to determine the corrected signal peak value of the effective received wave signal;

[0051] The waveform of the effective received wave signal is updated based on the corrected signal peak value.

[0052] In this solution, the method for performing waveform correction on the predicted received wave signal corresponding to the predicted waveform change curve based on the waveform correction solution is specifically as follows:

[0053] The third adjustment weight k of the first predicted received wave signal within the waveform freezing mode duration is c(1) Set to 1;

[0054] The third adjustment weight k of the last predicted received wave signal within the waveform freeze mode duration c(n) Set to 1-k a(t) ;

[0055] determining third adjustment weights of other predicted received wave signals within the duration of the waveform freeze mode by a linear interpolation method based on the third adjustment weight of the first predicted received wave signal and the third adjustment weight of the last predicted received wave signal within the duration of the waveform freeze mode;

[0056] Perform weighted calculation on the signal peak value of each predicted received wave signal and the signal peak value of the first valid received wave signal to determine the corrected signal peak value of the predicted received wave signal within the duration of the waveform freezing mode;

[0057] The waveform of the predicted received wave signal is updated based on the corrected signal peak value.

[0058] The present invention discloses an ultrasonic flowmeter and a gas meter trigger wave automatic adjustment method, the method comprising: obtaining a trigger voltage threshold Vth i , set the signal-to-noise ratio lower limit SNRmin i ; Obtain the received wave signal and perform gain processing to determine the amplitude of the processed received wave signal; Calculate the signal-to-noise ratio (SNR) based on the amplitude of the processed received wave signal and the noise amplitude; Compare the signal-to-noise ratio (SNR) with the lower limit of the signal-to-noise ratio (SNRmin) i The system compares the received signal and determines the final trigger voltage threshold. When SNR < SNRmin3, detection is stopped and restarted based on a preset interval time threshold. When the amplitude of the processed received wave signal exceeds the final trigger voltage threshold, a square wave signal is output. While outputting the square wave signal, the received wave signal is continuously acquired and gain processed, and the gain value used for the gain processing is recalculated. This invention can improve the anti-interference performance of the ultrasonic flowmeter, enabling the ultrasonic flowmeter to operate normally in more complex measurement situations and ensuring accurate measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 A flow chart showing an ultrasonic flow meter and a gas meter trigger wave automatic adjustment method provided by the present invention is shown;

[0060] Figure 2 The flowchart of the present invention for performing gain processing on the received wave signal is shown;

[0061] Figure 3 A flow chart of a method for determining a final trigger voltage threshold value provided by the present invention is shown;

[0062] Figure 4 A block diagram showing the working principle of the automatic adjustment of the trigger wave provided by the present invention;

[0063] Figure 5 A schematic diagram of the first wave detection method provided by the present invention is shown;

[0064] Figure 6A schematic diagram of the second wave detection method provided by the present invention is shown;

[0065] Figure 7 A schematic diagram of the third wave detection provided by the present invention is shown. DETAILED DESCRIPTION

[0066] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0067] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0068] Figure 1 The flowchart of the ultrasonic flow meter and the gas meter trigger wave automatic adjustment method provided by the present invention is shown.

[0069] like Figure 1 As shown, the present invention discloses an ultrasonic flow meter and a gas meter trigger wave automatic adjustment method, comprising:

[0070] S101, obtaining a trigger voltage threshold Vth preset by the system i ; The trigger voltage threshold includes the first wave trigger voltage threshold Vth1, the second wave trigger voltage threshold Vth2 and the third wave trigger voltage threshold Vth3;

[0071] S102, based on the trigger voltage threshold Vth i Set the signal-to-noise ratio lower limit SNRmin i The lower limits of the signal-to-noise ratio include the lower limit of the signal-to-noise ratio of the first wave trigger detection SNRmin1, the lower limit of the signal-to-noise ratio of the second wave trigger detection SNRmin2, and the lower limit of the signal-to-noise ratio of the third wave trigger detection SNRmin3.

[0072] S103, obtaining a received wave signal;

[0073] S104, performing gain processing on the received wave signal to determine the amplitude of the processed received wave signal;

[0074] S105, calculating a signal-to-noise ratio (SNR) based on the processed received wave signal amplitude and noise amplitude;

[0075] S106, compare the signal-to-noise ratio SNR with the signal-to-noise ratio lower limit SNRmin i Make a comparison and determine the final trigger voltage threshold;

[0076] S107, when SNR<SNRmin3, stop detection and restart detection based on a preset interval time threshold;

[0077] S108, comparing the processed received wave signal with the final trigger voltage threshold, and outputting a square wave signal when the amplitude of the processed received wave signal is higher than the final trigger voltage threshold;

[0078] S109: During the process of outputting the square wave signal, continuously acquiring the received wave signal and performing gain processing. When the amplitude of the processed received wave signal is not within a preset target amplitude range, recalculating the gain value used for the gain processing.

[0079] According to the embodiment of the present invention, since the received signal has a certain variation range, the trigger voltage threshold Vth i The system obtains the values ​​by analyzing the historical received wave signals. The first wave trigger voltage threshold Vth1, the second wave trigger voltage threshold Vth2 and the third wave trigger voltage threshold Vth3 are determined by the peak values ​​of the first wave, the second wave and the third wave respectively when the target range of the received signal is at the minimum. The initial values ​​of the three are generally 10%, 30% and 50% of the half-peak value of the received wave signal. The specific values ​​are determined by the system by analyzing the historical received wave signals.

[0080] based on Figure 4 The block diagram of the trigger wave automatic adjustment working principle is shown. Before each test begins, the system is initialized. The microprocessor 1 initializes the peak acquisition circuit 5, the logic control circuit 2, the trigger and zero-crossing control circuit 8, and the voltage divider circuit 11 composed of a digital potentiometer (or a voltage divider resistor). By reading the trigger voltage threshold Vth preset by the system i , and determine the corresponding signal-to-noise ratio lower limit SNRmin i .

[0081] Then, a round of detection is started by the microprocessor 1 according to a preset interval time threshold value preset by a person skilled in the art through the system to determine the detection time interval (for example, one second or two seconds). Before each round of detection, the amplifier 6 (PGA) and related circuits are started, and the amplifier 6 is adjusted according to the initial gain value or the gain value of the previous round of detection. At the same time, after an appropriate delay, the microprocessor 1 and the logic control circuit 3 control the enable comparator 4; then the microprocessor 1 starts to send the excitation wave signal, and after the shielding time set according to the caliber, the receiving wave signal 10 from the measuring channel receiving transducer and amplified by the amplifier 6 (PGA) is subjected to noise signal detection. Acquisition and detection, and after the comparator 4 outputs the first trigger pulse, start the received wave signal detection, perform gain processing on the acquired received wave signal, collect the signal amplitude of the received wave signal after gain processing, obtain the processed received wave signal amplitude, and calculate the signal-to-noise ratio in combination with the system preset noise amplitude (the signal-to-noise ratio corresponding to the received wave signal is also calculated using the signal-to-noise ratio lower limit calculation formula); if the received wave signal amplitude reaches the system preset target amplitude range, proceed to the next step; otherwise, recalculate the gain based on the obtained received wave signal amplitude, and repeat the above steps until the received wave signal amplitude reaches the preset target amplitude range.

[0082] Then, according to the calculated signal-to-noise ratio SNR, the microprocessor 1 controls the voltage divider circuit 11 of the digital potentiometer (or the voltage divider resistor) to obtain the corresponding trigger level 3 (i.e., the trigger voltage threshold, Vth i ), the voltage divider circuit is composed of a reference voltage source Vref, a resistor R1 and an adjustable potentiometer R2. The resistance value of the adjustable potentiometer R2 is adjusted by the microprocessor 1 to make the voltage output by the voltage divider circuit 11 equal to the calculated trigger voltage threshold Vth i Matching is as follows; when the signal-to-noise ratio SNR is higher than the set first-wave trigger detection signal-to-noise ratio lower limit SNRmin1, the microprocessor 1 controls the voltage divider circuit 11 of the digital potentiometer (or the voltage divider resistor) to output the first-wave trigger voltage threshold Vth1; when the signal-to-noise ratio SNR is lower than the set first-wave trigger detection signal-to-noise ratio lower limit SNRmin1 and higher than the second-wave trigger detection signal-to-noise ratio lower limit SNRmin2, the microprocessor 1 controls the voltage divider circuit 11 of the digital potentiometer (or the voltage divider resistor) to output the second-wave trigger voltage threshold Vth2; when the signal-to-noise ratio SNR is lower than the set second-wave trigger detection signal-to-noise ratio lower limit SNRmin2 and higher than the third-wave trigger detection signal-to-noise ratio lower limit SNRmin3, the microprocessor 1 controls the voltage divider circuit 11 of the digital potentiometer (or the voltage divider resistor) to output the third-wave trigger voltage threshold Vth3.

[0083] Afterwards, the microprocessor 1 simultaneously starts the comparator 4 to compare the received signal 10 with the selected final trigger voltage threshold (the first wave trigger voltage threshold Vth1, the second wave trigger voltage threshold Vth2 or the third wave trigger voltage threshold Vth3). When the amplitude of the received wave signal is higher than the final trigger voltage threshold, the comparator 4 starts to flip and output a high level. This high level prompts the trigger and zero-crossing control circuit 8 to control the comparator 7 to enter the zero-crossing comparison, thereby outputting a square wave signal 9 for timing processing.

[0084] like Figure 5-Figure 7 As shown, schematic diagrams of outputting square wave signals through first wave, second wave and third wave detection are listed respectively.

[0085] like Figure 5 As shown, within the noise detection time preset by the system, the current environment is determined to be a low-noise environment through the signal-to-noise ratio of the received wave signal, that is, SNR>SNRmin1, and the first-wave trigger level Vth1 (that is, the first-wave trigger voltage threshold) is determined as the final trigger voltage threshold. When the amplitude of the received wave signal (the processed received wave signal) output by the amplifier 6 is higher than the first-wave trigger level Vth1, the comparator 4 outputs a trigger square wave, and outputs a square wave signal through the comparator 7.

[0086] like Figure 6 As shown, within the noise detection time preset by the system, the current environment is determined to be a relatively noisy environment through the signal-to-noise ratio of the received wave signal, that is, SNRmin2≤SNR<SNRmin1, and the second wave trigger level Vth2 (that is, the second wave trigger voltage threshold) is determined as the final trigger voltage threshold. When the amplitude of the received wave signal (the processed received wave signal) output by the amplifier 6 is higher than the second wave trigger level Vth2, the comparator 4 outputs a trigger square wave, and the square wave signal is output through the comparator 7.

[0087] like Figure 7 As shown, within the noise detection time preset by the system, the current environment is determined to be a high-noise environment through the signal-to-noise ratio of the received wave signal, that is, SNRmin3≤SNR<SNRmin2, and the third wave trigger level Vth3 (that is, the third trigger voltage threshold) is determined as the final trigger voltage threshold. When the amplitude of the received wave signal (which is the processed received wave signal) output by the amplifier 6 is higher than the third trigger level Vth3, the comparator 4 outputs a trigger square wave, and the square wave signal is output through the comparator 7.

[0088] In addition, when the amplitude of the processed received wave signal is higher than the final trigger voltage threshold, the system will recalculate the signal-to-noise ratio (SNR) based on the received wave signal obtained each time, thereby dynamically adjusting the final trigger voltage threshold.

[0089] In addition, while controlling the relevant circuits (comparator 4 and comparator 7) to output square wave signals, microprocessor 1 continues to perform A / D conversion on the peak value sampled by peak acquisition circuit 5 on received wave signal 10, and obtains the received wave signal amplitude. If the received wave signal amplitude meets the required preset target amplitude range, subsequent processing is performed; otherwise, the gain value is recalculated, the gain of amplifier 6 is adjusted, and the signal-to-noise ratio is tested. This process is repeated until the amplitude of received wave signal 10 meets the required preset target amplitude range. At the same time, the signal-to-noise ratio (SNR) is calculated based on the recalculated and processed received wave signal amplitude. This SNR is compared with the lower limit of the signal-to-noise ratio (SNRmin3) for the third wave trigger detection, and a decision is made as to whether to continue outputting the square wave signal (i.e., SNR ≥ SNRmin3) or to cease detection (i.e., SNR < SNRmin3).

[0090] According to an embodiment of the present invention, based on the trigger voltage threshold Vth i Set the signal-to-noise ratio lower limit SNRmin i The specific method is:

[0091] ;

[0092] ;

[0093] Where i represents the i-th wave trigger, S represents the amplitude of the received wave signal after processing, and N i represents the noise amplitude of the i-th trigger wave, Vthi is the i-th wave trigger voltage threshold, and ΔV is the preset voltage adjustment parameter.

[0094] It should be noted that in order to ensure that noise does not cause false triggering and wave skipping when using the first wave, second wave or third wave detection, the maximum noise amplitude corresponding to each signal-to-noise ratio lower limit should be slightly lower than the corresponding trigger voltage threshold.

[0095] Here, i ranges from 1 to 3, representing first-wave triggering, second-wave triggering, and third-wave triggering, respectively. The received wave signal amplitude S generally ranges from 800 to 1000 mV, with the specific value determined by the preset target amplitude range pre-set by the system. The preset voltage adjustment parameter ΔV generally ranges from 10 mV to 50 mV, with the specific value set by those skilled in the art based on actual needs. Using the above formulas, we can determine the first-wave trigger detection signal-to-noise ratio lower limit SNRmin1 corresponding to the first-wave trigger voltage threshold Vth1, the second-wave trigger detection signal-to-noise ratio lower limit SNRmin2 corresponding to the second-wave trigger voltage threshold Vth2, and the third-wave detection signal-to-noise ratio lower limit SNRmin3 corresponding to the third-wave trigger voltage threshold Vth3.

[0096] Figure 2The flowchart of the gain processing of the received wave signal provided by the present invention is shown.

[0097] like Figure 2 As shown, according to an embodiment of the present invention, performing gain processing on a received wave signal to determine a processed received wave signal includes:

[0098] S201, performing gain processing on the received wave signal based on the initial gain value or the gain value detected in the previous round;

[0099] S202, determining whether the amplitude of the processed received wave signal is within a preset target amplitude range;

[0100] S203, if yes, output the amplitude of the processed received wave signal;

[0101] S204: If not, recalculate the gain value, and perform gain processing on the received wave signal again based on the recalculated gain value to obtain the amplitude of the processed received wave signal.

[0102] It should be noted that after each round of detection and acquisition of the received wave signal, the currently received received wave signal is gain-processed based on the gain value used in the previous round of detection, and the received wave signal is peak-adjusted to obtain the processed received wave signal amplitude for subsequent calculations. In the first round of detection, the received wave signal is gain-processed based on the initial gain value. The processed received wave signal amplitude is compared with the preset target amplitude range. If the amplitude is within the preset target amplitude range, the next step of processing is performed; otherwise, the gain value is recalculated to bring the received wave signal amplitude within the preset target amplitude range, completing the gain processing step of the received wave signal and obtaining the processed received wave signal amplitude.

[0103] The initial gain value and the preset target amplitude range are set by those skilled in the art according to actual needs.

[0104] Figure 3 The flowchart of the method for determining the final trigger voltage threshold provided by the present invention is shown.

[0105] like Figure 3 As shown, according to an embodiment of the present invention, the signal-to-noise ratio SNR and the signal-to-noise ratio lower limit SNRmin are i Compare and determine the final trigger voltage threshold, including:

[0106] S301, when SNR>SNRmin1, determining the first-wave trigger voltage threshold Vth1 as the final trigger voltage threshold;

[0107] S302 , when SNRmin2 ≤ SNR < SNRmin1 , determining the second wave trigger voltage threshold Vth2 as the final trigger voltage threshold;

[0108] S303 , when SNRmin3 ≤ SNR < SNRmin2 , determining the third wave trigger voltage threshold Vth3 as the final trigger voltage threshold.

[0109] It should be noted that based on Figure 4 The block diagram of the trigger wave automatic adjustment working principle is shown. According to the calculated signal-to-noise ratio SNR, the microprocessor 1 controls the voltage divider circuit 11 composed of a digital potentiometer (or a voltage divider resistor) to obtain the corresponding trigger level 3 (i.e., the trigger voltage threshold, Vth i ), specifically as follows; when the signal-to-noise ratio SNR is higher than the set first-wave trigger detection signal-to-noise ratio lower limit SNRmin1, the microprocessor 1 controls the voltage divider circuit 11 of the digital potentiometer (or the voltage divider resistor) to output the first-wave trigger voltage threshold Vth1; when the signal-to-noise ratio SNR is lower than the set first-wave trigger detection signal-to-noise ratio lower limit SNRmin1 and higher than the second-wave trigger detection signal-to-noise ratio lower limit SNRmin2, the microprocessor 1 controls the voltage divider circuit 11 of the digital potentiometer (or the voltage divider resistor) to output the second-wave trigger voltage threshold Vth2; when the signal-to-noise ratio SNR is lower than the set second-wave trigger detection signal-to-noise ratio lower limit SNRmin2 and higher than the third-wave trigger detection signal-to-noise ratio lower limit SNRmin3, the microprocessor 1 controls the voltage divider circuit 11 of the digital potentiometer (or the voltage divider resistor) to output the third-wave trigger voltage threshold Vth3.

[0110] According to an embodiment of the present invention, the further embodiment includes:

[0111] When SNR < SNRmin3, stop the test and record the cumulative stop time;

[0112] When the cumulative stop time is greater than the preset interval time threshold, the detection is restarted.

[0113] It should be noted that when the obtained signal-to-noise ratio (SNR) falls below the set lower limit (SNRmin3) for the third wave trigger detection signal-to-noise ratio, indicating that the noise level is too high to detect correctly, the microprocessor halts the detection process. Based on the time detection ceased, the accumulated stop time is recorded and compared with a preset interval time threshold. When the accumulated stop time exceeds the preset interval time threshold, the signal gain processing and SNR detection process are restarted to determine whether the test conditions have been restored. For example, the restored test conditions can be determined by determining whether the newly acquired SNR meets the final trigger voltage threshold, thereby resuming the trigger detection process for the corresponding received wave or continuing the detection process.

[0114] The preset interval time threshold is set by those skilled in the art according to actual needs.

[0115] According to an embodiment of the present invention, the further embodiment includes:

[0116] When the final trigger voltage threshold is the second wave trigger voltage threshold Vth2 or the third wave trigger voltage threshold Vth3, the forward and reverse sound wave transmission times corresponding to the square wave signal are corrected.

[0117] It should be noted that when the second wave trigger is used, the forward and reverse sound wave transmission time will be one cycle T longer than the first wave trigger. Therefore, one cycle T needs to be subtracted when calculating the forward and reverse durations for correction. Similarly, when the third wave trigger is used, the forward and reverse sound wave transmission time will be two cycles T longer than the first wave trigger. Therefore, two cycles T need to be subtracted when calculating the forward and reverse durations for correction. The period T is determined by the system based on the sampling frequency of the excitation signal. For example, if the excitation signal is 200kHz, the period T = 5us. The average period of detection can also be used for correction calculation.

[0118] According to an embodiment of the present invention, the further embodiment includes:

[0119] When SNR<SNRmin3, calculating the maximum peak-to-peak rate of change within the first preset time interval based on the historical received wave signals within the first preset time interval;

[0120] When the maximum peak-to-peak change rate within the first preset time interval is greater than a preset change rate threshold, entering a waveform freeze mode;

[0121] Recording the freeze mode duration based on the waveform freeze mode start time, and continuing to collect the received wave signal;

[0122] calculating a first peak-to-peak rate of change based on the received wave signal within a second preset time interval;

[0123] When the peak value change rate of the first wave is within the preset change rate threshold range, the waveform freezing model termination condition is met and the waveform freezing mode is exited;

[0124] When the freezing mode duration is greater than the preset time threshold, if the waveform freezing model termination condition is still not met, the detection is stopped.

[0125] It should be noted that the system determines the signal-to-noise ratio SNR and the signal-to-noise ratio lower limit SNRmin iHowever, when there are some short-duration (such as less than 50ms) and densely distributed transient interferences, the system needs to repeatedly trigger the stop detection and resume detection instructions, which requires greater system computing pressure. When the processor cannot meet the computing requirements, it cannot stop or resume detection in time, resulting in some trigger wave signals with a high signal-to-noise ratio or the loss of the trigger wave signal of the stop detection part, resulting in a large error between the detected flow data and the actual flow data. The waveform freezing mode can be added on the basis of the judgment of stopping detection to deal with transient interferences with a shorter duration.

[0126] When SNR is less than SNRmin3, the detection time corresponding to the current detection is determined as the end time of the first preset time interval. The first preset time interval is determined in combination with the preset interval length of the first preset time interval. Based on the historical detection time of the detection within the first preset time interval, the corresponding historical received wave signal is retrieved from the database. Among them, the received wave signal obtained by each detection is bound to the corresponding detection time and stored in the database. The peak difference between the minimum peak and the maximum peak in the selected historical received wave signal is calculated to determine the maximum peak-to-peak change rate. When the maximum peak-to-peak change rate is greater than the preset change rate threshold, it is determined that there is a short-duration and large-interference instantaneous interference, and the waveform freeze mode is entered first; otherwise, the detection is stopped directly.

[0127] The start time of the waveform freeze mode is determined as the start time of the first second preset time interval, and each second preset time interval is determined based on the interval length of the pre-set second preset time interval. Each second preset time interval is verified in chronological order. First, the absolute value of the peak difference of adjacent received wave signals in the second preset time interval is calculated. The absolute value of the peak difference of each adjacent received wave signal is multiplied by the corresponding change rate weight, and the calculation results are accumulated to determine the first peak-to-peak change rate. The change rate weight corresponding to the absolute value of the peak difference of adjacent received wave signals is determined by the system based on the time difference between the corresponding detection time of the previous received wave signal in the adjacent received wave signals and the current detection time. The closer to the current detection time, the higher the change rate weight corresponding to the absolute value of the peak difference of the corresponding adjacent received wave signal.

[0128] Among them, the interval lengths of the first preset time interval and the second preset time interval are set by those skilled in the art according to actual needs, and the preset change rate threshold, preset change rate threshold interval and preset time threshold are all set by those skilled in the art according to actual needs.

[0129] According to an embodiment of the present invention, the further embodiment includes:

[0130] When entering the waveform freeze mode, the historical received wave signal within the first preset time interval is input into the preset waveform change prediction model, and a predicted waveform change curve is output; the predicted waveform change curve includes a first predicted waveform change curve corresponding to the duration of the waveform freeze mode and a second predicted waveform change curve after exiting the waveform freeze mode;

[0131] After exiting the waveform freeze mode, the waveform correction scheme is determined based on the signal-to-noise ratio and waveform matching of the first valid received wave signal;

[0132] Based on the waveform correction scheme, waveform correction is performed on the predicted received wave signal corresponding to the predicted waveform change curve and the effective received wave signal after exiting the waveform freezing mode.

[0133] It should be noted that the preset waveform change prediction model is trained by the historical received wave signals obtained during the historical detection process. The preset waveform change prediction model can predict the waveform changes of the received wave signals in a certain period of time based on the waveform changes of the received wave signals in a certain period of time.

[0134] The first valid received wave signal is the first received wave signal obtained after exiting the waveform freeze mode.

[0135] The predicted received wave signal in waveform freeze mode is derived from a preset waveform change prediction model and may fluctuate slightly from the actual received wave signal in an unaffected environment. Similarly, the received wave signal immediately after exiting waveform freeze mode may also be subject to noise interference. Different waveform correction schemes are used to correct the waveform of the predicted received wave signal corresponding to the predicted waveform change curve and the effective received wave signal after exiting waveform freeze mode, eliminating these waveform deviations.

[0136] According to an embodiment of the present invention, a method for performing waveform correction on a valid received wave signal after exiting the waveform freeze mode based on a waveform correction scheme is specifically as follows:

[0137] Determine the first adjustment weight k of the first effective received wave signal according to the signal-to-noise ratio of the first effective received wave signal a(t) ;

[0138] Determine the adjustment time interval according to the waveform matching degree of the first valid received wave signal;

[0139] A first adjustment weight k based on the adjustment time interval and the first effective received wave signal a(t) The first adjustment weight of the subsequent valid received wave signal is set to determine the first adjustment weight k of the valid received wave signal at the detection time t+m a(t+m) ;

[0140] Based on the detection time T, the first adjustment weight k of the effective received wave signal is a(T) Determine the second adjustment weight k of the predicted received wave signal corresponding to the detection time b(T) ;k b(T) =1-k a(T) ;

[0141] Based on the detection time T, a weighted calculation is performed on the signal peak value of the effective received wave signal and the signal peak value of the corresponding predicted received wave signal to determine the corrected signal peak value of the effective received wave signal;

[0142] The waveform of the effective received wave signal is updated based on the corrected signal peak value.

[0143] It should be noted that the first adjustment weight k of the first valid received wave signal after exiting the waveform freeze mode is a(t) The system determines the first effective received wave signal based on the signal-to-noise ratio. The higher the signal-to-noise ratio, the corresponding first adjustment weight k a(t) The higher the value. For example, when SNR=15dB, k a(t) =0.5; when SNR=10dB, k a(t) =0.3. The waveform matching degree is obtained by comparing the signal waveform of the first valid received wave signal with the system preset reference waveform. The system determines the adjustment time interval based on the waveform matching degree of the first valid received wave signal. The higher the waveform matching degree, the smaller the corresponding adjustment time interval. For example, when the waveform matching degree is greater than 80%, the preset time interval is 2ms; when the waveform matching degree is between 60-80%, the preset time interval is 3ms. The first adjustment weight k based on the adjustment time interval and the first valid received wave signal a(t) , combined with the weight adjustment amplitude per unit time interval derived by the system based on the comprehensive evaluation of the signal-to-noise ratio and waveform matching of the first valid received wave signal (for example, the first adjustment weight is increased by 0.1 for each preset time interval), the first adjustment weight of the subsequent valid received wave signal after exiting the waveform freeze mode is set. Detection time t+m is the mth detection time after the detection time t corresponding to the first valid received wave signal after exiting the waveform freeze mode. For example, if there are x preset time intervals between detection time t+1 and detection time t, then the first adjustment weight k of the valid received wave signal at detection time t+1 is a( t+1 ) =k a(t) +x×e, where e is the weight adjustment amplitude per unit time interval.

[0144] The detection time T includes the detection time t corresponding to the first valid received wave signal and the detection time t+m corresponding to subsequent valid received wave signals. The corrected signal peak value of the valid received wave signal is calculated, and the waveform of the valid received wave signal is updated based on the corrected signal peak value of the valid received wave signal, completing the waveform correction of the valid received wave signal.

[0145] The calculation method of the signal peak value after the correction of the effective received wave signal is as follows:

[0146] ;

[0147] Among them, VT A(T) The peak value of the corrected effective received wave signal corresponding to the detection time T, VT a(T) The signal peak value of the effective receiving wave signal corresponding to the detection time T, VT b(T) k is the signal peak value of the predicted received wave signal corresponding to the detection time T, a(T) is the first adjustment weight of the effective received wave signal corresponding to the detection time T, k b(T) The second adjustment weight of the predicted received wave signal corresponding to the detection time T.

[0148] In addition, when the calculated first adjustment weight of the valid received wave signal corresponding to a certain detection time is greater than or equal to 1, the first adjustment weight of the valid received wave signal corresponding to the detection time is set to 1, and the calculation of the first adjustment weight of the valid received wave signal corresponding to the subsequent detection time is canceled. The subsequent detection times are all calculated based on the received wave signal actually detected.

[0149] According to an embodiment of the present invention, a method for performing waveform correction on a predicted received wave signal corresponding to a predicted waveform change curve based on a waveform correction scheme is specifically as follows:

[0150] The third adjustment weight k of the first predicted received wave signal within the waveform freezing mode duration is c(1) Set to 1;

[0151] The third adjustment weight k of the last predicted received wave signal within the waveform freeze mode duration c(n) Set to 1-k a(t) ;

[0152] determining third adjustment weights of other predicted received wave signals within the duration of the waveform freeze mode by a linear interpolation method based on the third adjustment weight of the first predicted received wave signal and the third adjustment weight of the last predicted received wave signal within the duration of the waveform freeze mode;

[0153] Perform weighted calculation on the signal peak value of each predicted received wave signal and the signal peak value of the first valid received wave signal to determine the corrected signal peak value of the predicted received wave signal within the duration of the waveform freezing mode;

[0154] The waveform of the predicted received wave signal is updated based on the corrected signal peak value.

[0155] It should be noted that the calculation method for predicting the signal peak value after correction of the received wave signal is specifically as follows:

[0156] ;

[0157] Among them, VT A(j) is the peak value of the jth predicted received wave signal after correction during the duration of the waveform freeze mode, VT a(j) is the signal peak value of the jth predicted received wave signal within the duration of the waveform freeze mode, VT a(t) k is the peak value of the first valid received wave signal after exiting the waveform freeze mode. c(j) is the third adjustment weight corresponding to the j-th predicted received wave signal.

[0158] The information (including but not limited to user device information, user personal information, etc.), data (including but not limited to data used for analysis, stored data, displayed data, etc.), and signals (including but not limited to signals transmitted between user terminals and other devices, etc.) involved in this application are all authorized by the user or fully authorized by all parties, and the collection, use, and processing of relevant data must comply with the relevant laws, regulations, and standards of the relevant countries and regions. For example, the "received wave signal" and "historical received wave signal" involved in this disclosure are all obtained with full authorization.

[0159] The present invention discloses an ultrasonic flowmeter and a gas meter trigger wave automatic adjustment method, the method comprising: obtaining a trigger voltage threshold Vth i , set the signal-to-noise ratio lower limit SNRmin i ; Obtain the received wave signal and perform gain processing to determine the amplitude of the processed received wave signal; Calculate the signal-to-noise ratio (SNR) based on the amplitude of the processed received wave signal and the noise amplitude; Compare the signal-to-noise ratio (SNR) with the lower limit of the signal-to-noise ratio (SNRmin) iThe system compares the received signal and determines the final trigger voltage threshold. When SNR < SNRmin3, detection is stopped and restarted based on a preset interval time threshold. When the amplitude of the processed received wave signal exceeds the final trigger voltage threshold, a square wave signal is output. While outputting the square wave signal, the received wave signal is continuously acquired and gain processed, and the gain value used for the gain processing is recalculated. This invention can improve the anti-interference performance of the ultrasonic flowmeter, enabling the ultrasonic flowmeter to operate normally in more complex measurement situations and ensuring accurate measurement.

[0160] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of units is merely a logical function division. In actual implementation, there may be other division methods, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0161] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units; they may be located in one place or distributed across multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the scheme of this embodiment.

[0162] In addition, all functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may be separately used as a unit, or two or more units may be integrated into one unit; the above-mentioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0163] Those skilled in the art will appreciate that all or part of the steps of the above-mentioned method embodiments may be implemented by hardware associated with program instructions, and the aforementioned program may be stored in a computer-readable storage medium. When the program is executed, the program executes the steps of the above-mentioned method embodiments. The aforementioned storage medium includes various media that can store program codes, such as mobile storage devices, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0164] Alternatively, if the integrated units described above are implemented as software modules and sold or used as standalone products, they can also be stored on a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of the present invention, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product, stored on a storage medium, includes instructions for enabling a computer device (such as a personal computer, server, or network device) to execute all or part of the methods of the various embodiments of the present invention. The aforementioned storage media include various media capable of storing program code, such as removable storage devices, ROM, RAM, magnetic disks, or optical disks.

Claims

1. A method for automatically adjusting trigger waves of an ultrasonic flowmeter and a gas meter, characterized in that: include: Get the trigger voltage threshold Vth preset by the system i ; The trigger voltage threshold includes the first wave trigger voltage threshold Vth1, the second wave trigger voltage threshold Vth2 and the third wave trigger voltage threshold Vth3; Based on the trigger voltage threshold Vth i Set the signal-to-noise ratio lower limit SNRmin i The signal-to-noise ratio lower limit includes the first wave trigger detection signal-to-noise ratio lower limit SNRmin1, the second wave trigger detection signal-to-noise ratio lower limit SNRmin2 and the third wave detection signal-to-noise ratio lower limit SNRmin3; Obtaining received wave signals; performing gain processing on the received wave signal to determine the amplitude of the processed received wave signal; Calculating a signal-to-noise ratio (SNR) based on the processed received wave signal amplitude and noise amplitude; The signal-to-noise ratio SNR is compared with the signal-to-noise ratio lower limit SNRmin i Make a comparison and determine the final trigger voltage threshold; When SNR < SNRmin3, stop the detection and restart the detection based on the preset interval time threshold; comparing the processed received wave signal with the final trigger voltage threshold, and outputting a square wave signal when the amplitude of the processed received wave signal is higher than the final trigger voltage threshold; During the process of outputting the square wave signal, the received wave signal is continuously acquired and gain processing is performed. When the amplitude of the processed received wave signal is not within the preset target amplitude range, the gain value for gain processing is recalculated.

2. The method for automatically adjusting the trigger wave of an ultrasonic flowmeter and a gas meter according to claim 1, characterized in that: Based on the trigger voltage threshold Vth i Set the signal-to-noise ratio lower limit SNRmin i The specific method is: ； ； Where i represents the i-th wave trigger, S represents the amplitude of the received wave signal after processing, and N i Indicates the noise amplitude triggered by the i-th wave, Vth i is the i-th wave trigger voltage threshold, and ΔV is the preset voltage adjustment parameter.

3. The method for automatically adjusting the trigger wave of an ultrasonic flowmeter and a gas meter according to claim 1, characterized in that: The performing gain processing on the received wave signal to determine the processed received wave signal includes: performing gain processing on the received wave signal based on an initial gain value or a gain value detected in a previous round; Determine whether the amplitude of the processed received wave signal is within a preset target amplitude range; If so, the amplitude of the received wave signal after processing is output; If not, the gain value is recalculated, and gain processing is performed again on the received wave signal based on the recalculated gain value to obtain the amplitude of the processed received wave signal.

4. The method for automatically adjusting the trigger wave of an ultrasonic flowmeter and a gas meter according to claim 1, characterized in that: The signal-to-noise ratio SNR is compared with the signal-to-noise ratio lower limit SNRmin i Compare and determine the final trigger voltage threshold, including: When SNR>SNRmin1, the first-wave trigger voltage threshold Vth1 is determined as the final trigger voltage threshold; When SNRmin2≤SNR<SNRmin1, the second wave trigger voltage threshold Vth2 is determined as the final trigger voltage threshold; When SNRmin3≤SNR<SNRmin2, the third wave trigger voltage threshold Vth3 is determined as the final trigger voltage threshold.

5. The method for automatically adjusting the trigger wave of an ultrasonic flowmeter and a gas meter according to claim 1, characterized in that: Also includes: When SNR < SNRmin3, stop the test and record the cumulative stop time; When the accumulated stop time is greater than the preset interval time threshold, the detection is restarted.

6. The method for automatically adjusting the trigger wave of an ultrasonic flowmeter and a gas meter according to claim 1, characterized in that: Also includes: When the final trigger voltage threshold is the second wave trigger voltage threshold Vth2 or the third wave trigger voltage threshold Vth3, the forward and reverse sound wave transmission times corresponding to the square wave signal are corrected.

7. The method for automatically adjusting the trigger wave of an ultrasonic flowmeter and a gas meter according to claim 1, characterized in that: Also includes: When SNR<SNRmin3, calculating the maximum peak-to-peak rate of change within the first preset time interval based on the historical received wave signals within the first preset time interval; When the maximum peak-to-peak change rate within the first preset time interval is greater than a preset change rate threshold, entering a waveform freezing mode; Recording the freeze mode duration based on the waveform freeze mode start time, and continuing to collect the received wave signal; calculating a first peak-to-peak rate of change based on the received wave signal within a second preset time interval; When the peak value change rate of the first wave peak is within a preset change rate threshold range, the waveform freezing model termination condition is met and the waveform freezing mode is exited; When the duration of the freezing mode is greater than a preset time threshold, if the waveform freezing model termination condition is still not met, the detection is stopped.

8. The method for automatically adjusting the trigger wave of an ultrasonic flowmeter and a gas meter according to claim 7, characterized in that: Also includes: When entering the waveform freeze mode, the historical received wave signal within the first preset time interval is input into the preset waveform change prediction model, and a predicted waveform change curve is output; the predicted waveform change curve includes a first predicted waveform change curve corresponding to the duration of the waveform freeze mode and a second predicted waveform change curve after exiting the waveform freeze mode; After exiting the waveform freeze mode, the waveform correction scheme is determined based on the signal-to-noise ratio and waveform matching of the first valid received wave signal; Based on the waveform correction scheme, waveform correction is performed on the predicted received wave signal corresponding to the predicted waveform change curve and the effective received wave signal after exiting the waveform freezing mode.

9. The method for automatically adjusting the trigger wave of an ultrasonic flowmeter and a gas meter according to claim 8, characterized in that: The method for performing waveform correction on the effective received wave signal after exiting the waveform freeze mode based on the waveform correction scheme is as follows: Determine the first adjustment weight k of the first effective received wave signal according to the signal-to-noise ratio of the first effective received wave signal a(t) ; Determine the adjustment time interval according to the waveform matching degree of the first valid received wave signal; A first adjustment weight k based on the adjustment time interval and the first effective received wave signal a(t) The first adjustment weight of the subsequent valid received wave signal is set to determine the first adjustment weight k of the valid received wave signal at the detection time t+m a(t+m) ; Based on the detection time T, the first adjustment weight k of the effective received wave signal is a(T) Determine the second adjustment weight k of the predicted received wave signal corresponding to the detection time b(T) ;k b(T) =1-k a(T) ; Based on the detection time T, a weighted calculation is performed on the signal peak value of the effective received wave signal and the signal peak value of the corresponding predicted received wave signal to determine the corrected signal peak value of the effective received wave signal; The waveform of the effective received wave signal is updated based on the corrected signal peak value.

10. The method for automatically adjusting the trigger wave of an ultrasonic flow meter and a gas meter according to claim 8, characterized in that: The method for performing waveform correction on the predicted received wave signal corresponding to the predicted waveform change curve based on the waveform correction scheme is specifically as follows: The third adjustment weight k of the first predicted received wave signal within the waveform freezing mode duration is c(1) Set to 1; The third adjustment weight k of the last predicted received wave signal within the waveform freeze mode duration c(n) Set to 1-k a(t) ; determining third adjustment weights of other predicted received wave signals within the duration of the waveform freeze mode by a linear interpolation method based on the third adjustment weight of the first predicted received wave signal and the third adjustment weight of the last predicted received wave signal within the duration of the waveform freeze mode; Perform weighted calculation on the signal peak value of each predicted received wave signal and the signal peak value of the first valid received wave signal to determine the corrected signal peak value of the predicted received wave signal within the duration of the waveform freezing mode; The waveform of the predicted received wave signal is updated based on the corrected signal peak value.

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