Signal detection method of ultrasonic wind meter
By adopting a combined analog-digital signal detection method in ultrasonic air detectors, analog detection or digital correlation calculation is used according to wind speed scenarios, the problem of poor signal detection accuracy in high wind speed scenarios is solved, and higher accuracy and wider range of wind speed measurements are achieved.
Patent Information
- Application Number
- CN202510177103.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-18
- Publication Date
- 2025-06-13
AI Technical Summary
Existing ultrasonic air meters are difficult to accurately detect signals in high wind speed scenarios, resulting in poor measurement accuracy and limiting the wind speed measurement range.
A combination of analog-to-digital methods is used to simulate detection in medium- and low wind speed scenarios based on signal intensity and signal-to-noise ratio, and analog-to-digital conversion and digital correlation calculation are performed in high wind speed scenarios to determine the signal arrival time.
Accurately extracting the signal arrival moment under different wind speed scenarios, improving the accuracy and range of wind measurement results, and expanding the application of ultrasonic air meter.
Smart Images
Figure CN120142693A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of ultrasonic anemometers, and in particular to a signal detection method for an ultrasonic anemometer. Background Art
[0002] Wind measurement technology is one of the most basic contents in the field of meteorological observation. The most important thing in wind measurement technology is to measure two physical quantities: wind speed and wind direction. Currently, common wind measurement instruments include mechanical anemometers, ultrasonic anemometers, dynamic pressure anemometers, thermal anemometers, lidar wind profilers, and wind profile radars.
[0003] An ultrasonic anemometer calculates the change in air flow by measuring the Doppler time change of the propagation time of ultrasonic waves in the air, and then obtains the wind measurement result. Compared with traditional mechanical anemometers, ultrasonic anemometers are increasingly used because they do not have the wear of mechanical rotating parts, and have better measurement accuracy, sensitivity, and dynamic response.
[0004] Although ultrasonic anemometers have the above advantages, current ultrasonic anemometers usually adopt analog signal detection methods, which have relatively high requirements for the signal intensity and signal-to-noise ratio of the received ultrasonic signals. When ultrasonic signals propagate in the air, not only the speed is affected by air flow, but also the signal intensity changes with air flow, air density, and air pressure. For example, the signal received by the ultrasonic probe at the windward end will become stronger, while the signal received in the opposite direction will become weaker. If received perpendicular to the air flow direction, the received signal intensities in both the forward and reverse directions will decrease simultaneously. This results in particularly large changes in the signal intensity of the transmitted and received signals at high wind speeds, and also large changes in the pulse shape, which brings difficulties to signal detection, causing problems such as inability to measure or poor measurement accuracy, and greatly limiting the wind speed measurement range of ultrasonic anemometers. Summary of the Invention
[0005] In view of the above problems and technical requirements, this application proposes a signal detection method for an ultrasonic anemometer. The technical solution of this application is as follows:
[0006] A signal detection method for an ultrasonic anemometer, the signal detection method includes:
[0007] When it is determined that the current is in a medium or low wind speed scenario, perform analog detection on the obtained analog received signal to obtain the signal arrival time;
[0008] When it is determined that the current is in a high wind speed scenario, perform analog-to-digital conversion on the obtained analog received signal to obtain a digital received signal, perform feature analysis and extraction on the digital received signal to obtain signal features, determine a corresponding target reference signal according to the signal features of the digital received signal, and obtain the signal arrival time according to the correlation degree between the digital received signal and the target reference signal.
[0009] The wind measurement result is obtained according to the signal arrival time.
[0010] A further technical solution thereof is that the signal arrival time is obtained according to the correlation degree between the digital received signal and the target reference signal, including:
[0011] The correlation coefficients of the digital received signal at each sampling time and the target reference signal are calculated respectively, and the sampling time corresponding to the maximum value among all the correlation coefficients is used as the signal arrival time.
[0012] A further technical solution thereof is that calculating the correlation coefficient of the digital received signal at each sampling time and the target reference signal includes:
[0013] The target reference signal is shifted until each reference time in the target reference signal corresponds to each sampling time of the digital received signal respectively, and the correlation coefficient of the signal values of the digital received signal and the target reference signal at the corresponding sampling times is calculated.
[0014] A further technical solution thereof is that the correlation coefficient of the signal values of the digital received signal and the target reference signal at any corresponding sampling time i is:
[0015]
[0016] where X i is the signal value of the digital received signal at the sampling time i, H i is the signal value of the target reference signal at the sampling time i, and n is the total number of sampling times in the digital received signal and the target reference signal.
[0017] A further technical solution thereof is that determining the corresponding target reference signal according to the signal characteristics of the digital received signal includes:
[0018] Determining the local reference signal with the highest similarity of signal characteristics to the signal characteristics of the digital received signal as the target reference signal, and the signal characteristics include signal strength characteristics and frequency characteristics.
[0019] A further technical solution thereof is that the signal detection method further includes:
[0020] Determining whether the current is in a medium-low wind speed scenario or a high wind speed scenario according to the signal amplitude of the acquired analog received signal.
[0021] A further technical solution thereof is that determining whether the current is in a medium-low wind speed scenario or a high wind speed scenario according to the signal amplitude of the acquired analog received signal includes:
[0022] After signal filtering is performed on the analog received signal, under the condition that the signal noise in the amplified analog received signal does not exceed the noise threshold, the analog received signal is amplified to the maximum extent to obtain the amplified analog received signal;
[0023] Determine whether the current is in a medium-low wind speed scenario or a high wind speed scenario according to the signal amplitude of the amplified analog received signal.
[0024] A further technical solution thereof is that determining whether the current is in a medium-low wind speed scenario or a high wind speed scenario according to the signal amplitude of the amplified analog received signal includes:
[0025] When the signal amplitude of the first pulse of the amplified analog received signal exceeds the comparator threshold of analog detection, determine that the current is in a medium-low wind speed scenario; otherwise, determine that the current is in a high wind speed scenario.
[0026] A further technical solution thereof is that performing analog-to-digital conversion on the obtained analog received signal to obtain a digital received signal includes:
[0027] Performing analog-to-digital conversion on the amplified analog received signal to obtain an original digital signal, and performing digital filtering on the original digital signal to obtain a digital received signal.
[0028] A further technical solution thereof is that performing digital filtering on the original digital signal to obtain a digital received signal includes:
[0029] Performing digital filtering on the original digital signal by using an FIR band-pass filter or an IIR band-pass filter to obtain a digital received signal.
[0030] The beneficial technical effects of this application are:
[0031] This application discloses a signal detection method for an ultrasonic anemometer. The signal detection method uses a method combining analog and digital to extract the signal arrival time based on the obtained analog received signal. In a low wind speed scenario, the analog received signal with high signal strength and signal-to-noise ratio is directly subjected to analog detection to obtain the signal arrival time, and the implementation method is simple and the measurement accuracy is relatively high; while in a high wind speed scenario, the analog received signal with low signal strength and signal-to-noise ratio is sampled to obtain a digital received signal, and then feature extraction is performed on the digital received signal to determine the target reference signal and then perform a correlation calculation with the digital received signal, so as to obtain the signal arrival time through digital detection. This method adopts a combination of analog detection and digital correlation calculation detection, and can accurately extract the signal arrival time in different wind speed scenarios to obtain the wind measurement result, expanding the application range of the ultrasonic anemometer, so that the ultrasonic anemometer can have a relatively accurate and high-precision wind measurement result in the full wind speed scenario.
[0032] Considering that the digital signal related calculation method requires high-speed sampling, high-speed calculation and processing assistance, which has high requirements for devices such as processors, resulting in high power consumption and high cost. However, in most actual scenarios, it is a high signal-to-noise ratio situation under low wind speed. The analog signal related calculation method can meet the wind measurement requirements. Therefore, this application adopts a combined method of analog calculation under low wind speed and digital calculation under high wind speed, which can balance the wind measurement requirements and the low energy consumption requirements of the system. Description of the Drawings
[0033] Figure 1 It is a flowchart of the signal detection method according to an embodiment of the present application.
[0034] Figure 2 It is a flowchart of the signal detection method according to another embodiment of the present application.
[0035] Figure 3 It is a signal diagram of the amplified analog received signal in the medium and low wind speed scenario obtained in an example.
[0036] Figure 4 It is a signal diagram of the amplified analog received signal in the high wind speed scenario obtained in an example.
[0037] Figure 5 It is for Figure 4 It is a signal diagram of the digital received signal obtained after analog-to-digital conversion of the amplified analog received signal in the example.
[0038] Figure 6 It is for Figure 5 It is a diagram of the correlation coefficient calculated from the digital received signal in the example. Detailed Embodiments
[0039] The following further describes the detailed embodiments of the present application with reference to the drawings.
[0040] The present application discloses a signal detection method for an ultrasonic anemometer. This signal detection method can be applied to various ultrasonic anemometers such as existing two-dimensional ultrasonic anemometers and three-dimensional ultrasonic anemometers. This signal detection method is overall based on the ultrasonic time difference measurement principle used by existing ultrasonic anemometers. For each measurement direction, after determining the signal arrival time of this measurement direction, the time difference of this measurement direction can be obtained, and thus the wind measurement results including wind speed and wind direction can be calculated.
[0041] This application focuses on improving the method for determining the signal arrival time of each measurement direction. The traditional method is to directly perform analog detection on the acquired analog received signal to obtain the signal arrival time. However, this method may encounter problems such as inability to measure or low measurement accuracy in some application scenarios, especially in high wind speed scenarios. Therefore, this application optimizes this method and adopts different strategies to determine the signal arrival time in different wind speed scenarios, mainly divided into medium and low wind speed scenarios and high wind speed scenarios. Please refer to Figure 1 the flowchart shown in Figure 2 and the flowchart shown in
[0042] When it is determined that the current is in a medium and low wind speed scenario, the acquired analog received signal is subjected to analog detection according to the traditional method to obtain the signal arrival time. When it is determined that the current is in a high wind speed scenario, the acquired analog received signal is subjected to analog-to-digital conversion to obtain a digital received signal, and then the signal arrival time is obtained based on the digital received signal. Thus, the signal arrival time can be determined respectively by using the method combining analog and digital in different wind speed scenarios. On the basis of quickly and efficiently detecting the signal arrival time through analog detection in the medium and low wind speed scenario, the deficiencies of analog detection in the high wind speed scenario are made up by using digital domain signal processing.
[0043] The medium and low wind speed scenarios and high wind speed scenarios referred to in this application are relative wind speed intervals and there is no specific division method. In one embodiment, the current being in a medium and low wind speed scenario or a high wind speed scenario can be determined according to the signal amplitude of the acquired analog received signal, including:
[0044] First, the acquired analog received signal is subjected to signal filtering to remove out-of-band and pulse carriers. Then, the analog received signal after signal filtering is subjected to signal amplification, including performing maximum signal amplification on the analog received signal under the condition that the signal noise in the amplified analog received signal does not exceed the noise threshold, that is, obtaining the amplified analog received signal, which means that on the premise of ensuring that the circuit noise does not deteriorate, the filtered analog received signal is amplified as much as possible to the strongest.
[0045] In the medium and low wind speed scenario, the signal amplitude of the amplified analog received signal is relatively large and the waveform is relatively stable. In many cases, it will be oversaturated. In one example, the amplified analog received signal in the medium and low wind speed scenario is as shown in Figure 3 shown.
[0046] In the high wind speed scenario, the violent air flow will cause the signal amplitude of the analog received signal to decrease and the shape of the signal to change violently. In one example, the amplified analog received signal in the high wind speed scenario is as shown in Figure 4As shown. Even if the analog received signal is adjusted to the maximum as much as possible without deteriorating the noise, the signal strength of the amplified analog received signal still cannot reach the comparator threshold of the analog detection. At this time, if the comparator threshold of the analog detection is lowered, it will cause detection errors and detect incorrect periods. Moreover, due to the very low signal-to-noise ratio, noise interference can easily cause the comparator of the analog detection to produce incorrect outputs. This is also the reason why the current analog detection has poor effects in high-wind speed scenarios.
[0047] Since the signal characteristics of the amplified analog received signal are the same in medium and low wind speed scenarios and high wind speed scenarios, the current wind speed scenario (medium and low wind speed scenario or high wind speed scenario) can be determined based on the signal amplitude of the amplified analog received signal: when the signal amplitude of the first pulse of the amplified analog received signal exceeds the comparator threshold of the analog detection, it is determined that the current is in the medium and low wind speed scenario; otherwise, it is determined that the current is in the high wind speed scenario.
[0048] When it is determined that the current is in the medium and low wind speed scenario, the analog detection of the analog received signal is performed according to the traditional method to obtain the signal arrival time. Actually, it is the analog detection of the amplified analog received signal to obtain the signal arrival time. For example, a comparator is used to detect the rising edge of the signal in a certain period of the amplified analog received signal, and the generated signal comparison level is sent to a high-precision counter. Since the amplified analog received signal is continuous, the accuracy judgment of the arrival time after passing through the comparator is only affected by the counter. By using a timer chip with nanosecond-level or even finer precision, a very high time measurement accuracy can be obtained. Therefore, the signal arrival time can be extracted with high precision.
[0049] When it is determined that the current is in the high wind speed scenario, since the signal amplitude and signal-to-noise ratio of the amplified analog received signal are both low, the means of analog detection can no longer be used, and the digital detection processing method is then switched to:
[0050] (1) The analog received signal obtained is subjected to analog-to-digital conversion to obtain a digital received signal. This includes performing analog-to-digital conversion on the amplified analog received signal to obtain the original digital signal D(n), and then performing digital filtering on the original digital signal D(n) to obtain the digital received signal X(n), where n is the number of sampling times in the original digital signal and the digital received signal.
[0051] Performing digital filtering on the original digital signal D(n) can further remove interference and clutter. In one embodiment, the original digital signal D(n) is digitally filtered using an FIR band-pass filter or an IIR band-pass filter to obtain the digital received signal X(n). In one example, the digital received signal X(n) obtained after performing analog-to-digital conversion and digital filtering on the amplified analog received signal in the high wind speed scenario shown in Figure 4 is as shown in Figure 5 shown. It should be noted thatFigure 5 It appears as a continuous curve for illustrative purposes, but is actually a discrete curve.
[0052] (2) Perform feature analysis and extraction on the digital received signal X(n) to obtain signal features. The feature analysis method used in this step can adopt various existing signal feature extraction methods. In one embodiment, the signal features of the digital received signal X(n) obtained by extraction include signal strength features and frequency features.
[0053] (3) Determine the corresponding target reference signal H(n) according to the signal features of the digital received signal X(n). This application pre-maintains several local reference signals. After determining the signal features of the digital received signal X(n), the local reference signal with the highest similarity to the signal features of the digital received signal X(n) is determined as the target reference signal H(n). Among them, each local reference signal is a digital signal with a standard signal form pre-stored.
[0054] (4) Obtain the signal arrival time according to the correlation degree between the digital received signal and the target reference signal.
[0055] In one embodiment, calculate the correlation coefficient between the digital received signal and the target reference signal at each sampling time respectively, and take the sampling time corresponding to the maximum value among all the correlation coefficients as the signal arrival time. For example, in Figure 6 the example, the sampling time 113 corresponding to the maximum value among all the correlation coefficients is taken as the signal arrival time. Since the digital received signal and the target reference signal may not be aligned, in one embodiment, first shift the target reference signal until each reference time in the target reference signal corresponds to each sampling time in the digital received signal respectively, and then calculate the correlation coefficient of the signal values of the digital received signal and the target reference signal at the corresponding sampling times.
[0056] The correlation coefficient of the signal values of the digital received signal X(n) and the target reference signal H(n) at any corresponding sampling time i is:
[0057]
[0058] where X i is the signal value of the digital received signal at sampling time i, H i is the signal value of the target reference signal at sampling time i, and n is the total number of sampling times in the digital received signal and the target reference signal.
[0059] In one example, the curve formed by the correlation coefficients at different sampling times calculated for the Figure 5 shown digital received signal X(n) is as Figure 6 shown.
[0060] Whether in a low or medium wind speed scenario or a high wind speed scenario, the signal arrival time can be detected using the corresponding methods, and then the time difference can be obtained based on the signal arrival time according to the traditional method, so as to calculate the wind measurement results including wind speed and wind direction. When the ultrasonic anemometer includes multiple measurement directions, wind measurement can be performed for each measurement direction according to various methods.
[0061] The above is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.
Claims
1. A signal detection method for an ultrasonic anemometer, characterized in that: The signal detection method comprises: When it is determined that the current scene is in a medium or low wind speed scenario, analog detection is performed on the acquired analog received signal to obtain the signal arrival time; When it is determined that the current scene is a high wind speed scene, performing analog-to-digital conversion on the acquired analog received signal to obtain a digital received signal, performing feature analysis on the digital received signal to extract a signal feature, and determining a corresponding target reference signal according to the signal feature of the digital received signal, and obtaining a signal arrival time according to a correlation between the digital received signal and the target reference signal; The wind measurement result is obtained according to the arrival time of the signal.
2. The signal detection method according to claim 1, characterized in that: The obtaining of the signal arrival time according to the correlation between the digital received signal and the target reference signal comprises: The correlation coefficient between the digital received signal and the target reference signal is calculated at each sampling time, and the sampling time corresponding to the maximum value of all the correlation coefficients is taken as the signal arrival time.
3. The signal detection method according to claim 2, characterized in that: Calculating the correlation coefficient between the digital received signal and the target reference signal at each sampling time includes: The target reference signal is shifted until each reference moment in the target reference signal corresponds to each sampling moment of the digital received signal, and correlation coefficients of signal values of the digital received signal and the target reference signal at the corresponding sampling moments are calculated.
4. The signal detection method according to claim 3, characterized in that: The correlation coefficient between the signal values of the digital received signal and the target reference signal at corresponding arbitrary sampling times is: Among them, is the signal value of the digital received signal at the sampling time, is the signal value of the target reference signal at the sampling time, and is the total number of sampling times in the digital received signal and the target reference signal.
5. The signal detection method according to claim 1, characterized in that: Determining a corresponding target reference signal according to a signal characteristic of the digital received signal includes: A local reference signal whose signal characteristics are most similar to the signal characteristics of the digital received signal is determined as the target reference signal, wherein the signal characteristics include signal strength characteristics and frequency characteristics.
6. The signal detection method according to claim 1, characterized in that: The signal detection method further comprises: It is determined whether the current wind speed is in a low to medium wind speed scenario or a high wind speed scenario according to the signal amplitude of the acquired analog received signal.
7. The signal detection method according to claim 6, characterized in that: Determine whether the current wind speed is low or medium based on the amplitude of the analog received signal, including: After filtering the analog received signal, the analog received signal is amplified to the maximum extent under the condition that the signal noise in the amplified analog received signal does not exceed the noise threshold, so as to obtain the amplified analog received signal; The current situation is determined to be a low to medium wind speed scenario or a high wind speed scenario according to the signal amplitude of the amplified analog received signal.
8. The signal detection method according to claim 7, characterized in that: Determining whether the current wind speed is in a low to medium wind speed scenario or a high wind speed scenario according to the signal amplitude of the amplified analog received signal includes: When the signal amplitude of the first pulse of the amplified analog received signal exceeds the comparator threshold of the analog detection, it is determined that the current scene is in a medium-low wind speed scene; otherwise, it is determined that the current scene is in a high wind speed scene.
9. The signal detection method according to claim 7, characterized in that: Performing analog-to-digital conversion on the acquired analog received signal to obtain a digital received signal includes: The amplified analog received signal is converted into a digital signal to obtain an original digital signal, and the original digital signal is digitally filtered to obtain the digital received signal.
10. The signal detection method according to claim 9, characterized in that: Performing digital filtering on the original digital signal to obtain the digital received signal includes: The original digital signal is digitally filtered using an FIR bandpass filter or an IIR bandpass filter to obtain the digital received signal.