Millimeter wave radar liquid level detection method and device and storage medium

Abstract

The application is suitable for the field of radar technology, and provides a millimeter wave radar liquid level detection method, device and storage medium. The method comprises the following steps: transmitting a wide-beam detection signal and a narrow-beam detection signal, receiving a wide-beam echo signal and a narrow-beam echo signal, obtaining a wide-beam spectrum and a narrow-beam spectrum according to the detection signal and the echo signal, then determining whether an obstacle is a ground or a liquid surface, obtaining a target spectrum according to the narrow-beam spectrum, and finally calculating the distance between the obstacle and the detection device according to the target spectrum. The millimeter wave radar liquid level detection method, device and storage medium provided by the application can determine whether the obstacle is a ground or a liquid surface by combining the wide-beam spectrum and the narrow-beam spectrum, and can detect the distance between the obstacle and the detection device at the same time, so that the radar liquid level detection device can be applied to more application scenarios.

Description

Technical Field

[0001] This application belongs to the field of radar technology, and in particular relates to millimeter-wave radar liquid level detection methods, devices and storage media. Background Technology

[0002] Currently, in addition to applications in hydrological monitoring stations and reservoirs, radar level gauges are widely used in urban flood monitoring and early warning systems in my country. They can monitor bridges, culverts, drainage pipes, canals, sunken roads, underground parking lots, and urban rivers and lakes in real time, providing support for decision-making, emergency response, and early warning, and safeguarding the lives of urban buildings and citizens under rainstorm conditions.

[0003] Radar level gauges are general-purpose radar level gauges. They are liquid level measurement devices based on the principle of time-domain reflectometry. The electromagnetic pulse signal emitted by the radar propagates at the speed of light. When it encounters the surface of the measured medium, part of the radar pulse signal is reflected to form an echo signal. The echo signal returns to the pulse transmitting device along the same path. Since the distance between the radar and the surface of the measured medium is proportional to the propagation time of the pulse signal between them, the liquid level height can be calculated based on the obtained propagation time and the speed of light.

[0004] However, current radar level gauges cannot determine the type of target obstacle, which limits their application scenarios. Summary of the Invention

[0005] This application provides a millimeter-wave radar liquid level detection method, device, and storage medium, which can solve problems such as the inability of radar level gauges to determine the type of obstacle.

[0006] In a first aspect, embodiments of this application provide a millimeter-wave radar method for detecting liquid levels, including:

[0007] It transmits wide-beam detection signals and narrow-beam detection signals, and receives wide-beam echo signals and narrow-beam echo signals formed after reflection from obstacles, wherein the detection angle of the wide-beam detection signal is greater than the detection angle of the narrow-beam detection signal;

[0008] Based on the wide beam detection signal, the wide beam echo signal, the narrow beam detection signal, and the narrow beam echo signal, after signal processing, the wide beam spectrum and the narrow beam spectrum are obtained respectively.

[0009] Based on the wide beam spectrum and the narrow beam spectrum, the obstacle is determined to be either ground or liquid surface;

[0010] The target spectrum is obtained based on the narrow beam spectrum, and the distance between the obstacle and the detection device is calculated based on the target spectrum.

[0011] In one possible implementation of the first aspect, determining whether the obstacle is ground or liquid surface based on the wide-beam spectrum and the narrow-beam spectrum includes:

[0012] The wide beam spectrum has a first energy peak and a first energy amplitude, the difference between the first energy peak and the first energy amplitude is a first predetermined difference, the two frequency points corresponding to the first energy amplitude are a first frequency point and a second frequency point, and the sum of the energy amplitudes between the first frequency point and the second frequency point is B1;

[0013] The narrow beam spectrum has a second energy peak, a second energy amplitude, and a third energy amplitude. The difference between the second energy peak and the second energy amplitude is a first predetermined difference. The two frequency points corresponding to the second energy amplitude are the third frequency point and the fourth frequency point. The sum of the energy amplitudes between the third frequency point and the fourth frequency point is B2. The difference between the second energy peak and the third energy amplitude is a second predetermined difference. The second predetermined difference is greater than the first predetermined difference. The two frequency points corresponding to the third energy amplitude are the fifth frequency point and the sixth frequency point. The sum of the energy amplitudes between the fifth frequency point and the sixth frequency point is B3.

[0014] Determine if (B3-B2) / B1 is greater than 10%;

[0015] If so, then the obstacle is determined to be a liquid surface;

[0016] If not, then the obstacle is determined to be the ground.

[0017] In one possible implementation of the first aspect, the first predetermined difference is 2 dB to 6 dB, and the second predetermined difference is 8 dB to 13 dB.

[0018] In one possible implementation of the first aspect, determining whether the obstacle is ground or liquid surface based on the wide-beam spectrum and the narrow-beam spectrum includes:

[0019] Determine whether both the wide-beam spectrum and the narrow-beam spectrum are symmetrical structures;

[0020] If so, then the obstacle is determined to be a liquid surface;

[0021] If not, then the obstacle is determined to be water.

[0022] In one possible implementation of the first aspect, obtaining the target spectrum based on the narrow beam spectrum includes:

[0023] The target spectrum is the narrow beam spectrum; or...

[0024] The target spectrum is an equivalent narrow beam spectrum. After determining that the obstacle is a liquid surface and before calculating the distance between the obstacle and the detection device, the narrow beam detection signal and the narrow beam echo signal are processed to obtain a narrow beam symmetrical spectrum. The narrow beam symmetrical spectrum has an energy peak A, and the function corresponding to the narrow beam symmetrical spectrum is F1.

[0025] The narrow beam spectrum has a second energy peak and a fourth energy amplitude. The difference between the second energy peak and the fourth energy amplitude is a third predetermined difference. The two frequency points corresponding to the fourth energy amplitude are the seventh frequency point and the eighth frequency point, respectively. The average value of the energy amplitude between the seventh frequency point and the eighth frequency point is B4.

[0026] The function corresponding to the equivalent narrow beam spectrum is (B4 / A)F1.

[0027] In one possible implementation of the first aspect, calculating the distance between the obstacle and the detection device based on the target spectrum includes:

[0028] The target frequency of the target spectrum is obtained, and the time edge τ corresponding to the target frequency is calculated. The distance between the obstacle and the detection device is R = 0.5τc, where c is the speed of light.

[0029] In one possible implementation of the first aspect, the target frequency is the peak frequency of the target spectrum; or,

[0030] The target spectrum has a first frequency and a second frequency on both sides of its peak frequency. The frequency band between the first frequency and the second frequency is refined by chirp-Z spectrum refinement. The frequency at which the index of the maximum amplitude of the refined spectrum is located is the target frequency.

[0031] In one possible implementation of the first aspect, the detection angle of the wide-beam detection signal is greater than or equal to 40°, and the detection angle of the narrow-beam detection signal is less than or equal to 60°.

[0032] The beneficial effects of this application embodiment compared to the prior art are as follows: It transmits both wide-beam and narrow-beam detection signals, simultaneously obtaining both wide-beam and narrow-beam echo signals. When the obstacle is ground, both the wide-beam and narrow-beam spectrum curves are relatively smooth, with energy concentrated in the high and low frequencies; when the obstacle is water, both the wide-beam and narrow-beam spectrum curves are relatively steep, with energy concentrated in the mid-frequency range. By combining the wide-beam and narrow-beam spectra, it is possible to determine whether the obstacle is ground or liquid, and simultaneously detect the distance between the obstacle and the detection device, making the radar liquid surface detection device applicable to more application scenarios.

[0033] Secondly, embodiments of this application provide a millimeter-wave radar liquid level detection device, including a millimeter-wave antenna for transmitting and receiving signals, a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the above-described method when executing the computer program.

[0034] Thirdly, embodiments of this application provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.

[0035] It is understood that the beneficial effects of the second and third aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic flowchart of a millimeter-wave radar liquid level detection method provided in an embodiment of this application;

[0038] Figure 2 This is a time-frequency relationship diagram of the detection signal and the echo signal in the embodiments of this application;

[0039] Figure 3 This is a schematic flowchart of a millimeter-wave radar liquid level detection method provided in another embodiment of this application;

[0040] Figure 4 This is a schematic flowchart of a millimeter-wave radar liquid level detection method provided in another embodiment of this application;

[0041] Figure 5 These are the wide-beam spectrum and narrow-beam spectrum diagrams when the obstacle is a liquid surface in the embodiments of this application;

[0042] Figure 6 This is a beam spectrum diagram when the obstacle is the ground in an embodiment of this application;

[0043] Figure 7 These are the narrow beam spectrum diagram and equivalent narrow beam spectrum diagram of the liquid surface fluctuation in the embodiments of this application. Detailed Implementation

[0044] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0045] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0046] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0047] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0048] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0049] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0050] The present application provides a method for detecting liquid level using millimeter-wave radar.

[0051] In one embodiment of this application, please refer to Figure 1 The millimeter-wave radar liquid level detection method includes the following steps:

[0052] S10: Transmit a wide-beam detection signal and a narrow-beam detection signal, and receive the wide-beam echo signal and the narrow-beam echo signal after being reflected by the obstacle, wherein the detection angle of the wide-beam detection signal is greater than the detection angle of the narrow-beam detection signal.

[0053] The frequency variation patterns of wide-beam detection signals and narrow-beam detection signals may be the same or different; both can be frequency-modulated continuous waves. The detection angle of the wide-beam detection signal is larger than that of the narrow-beam detection signal. The echo obtained after the wide-beam detection signal is reflected by an obstacle is the wide-beam echo signal, and the frequency variation patterns of the wide-beam detection signal and the wide-beam echo signal are the same. Similarly, the echo obtained after the narrow-beam detection signal is reflected by an obstacle is the narrow-beam echo signal, and the frequency variation patterns of the narrow-beam detection signal and the narrow-beam echo signal are the same.

[0054] S20: Based on the wide beam detection signal, the wide beam echo signal, the narrow beam detection signal, and the narrow beam echo signal, after signal processing, the wide beam spectrum and the narrow beam spectrum are obtained respectively.

[0055] There is a time delay between the wide-beam detection signal and the wide-beam echo signal. Since the beam propagation efficiency is the speed of light, this time delay is short and difficult to measure. However, the frequencies of both the wide-beam detection signal and the wide-beam echo signal change over time. Therefore, the time delay between the wide-beam detection signal and the wide-beam echo signal can be indirectly determined by obtaining the frequency difference between them at the same time (wide-beam spectrum). The narrow-beam detection signal and the narrow-beam echo signal are similar to those of the wide-beam detection signal and the wide-beam echo signal, and will not be described further here.

[0056] S30: Compare the wide beam spectrum and the narrow beam spectrum to determine whether the obstacle is ground or liquid surface;

[0057] The ground surface is rougher than the liquid surface. When the obstacle is ground, both the wide-beam and narrow-beam spectrum curves are smoother, with energy concentrated in the high and low frequencies. When the obstacle is water, both the wide-beam and narrow-beam spectrum curves are steeper, with energy concentrated in the mid-frequency range. Furthermore, the narrow-beam detection signal has a smaller detection range and more concentrated energy, making it more accurate for distance detection on smooth surfaces. The wide-beam detection signal has a larger detection range and more dispersed energy. Combining the wide-beam and narrow-beam spectra can serve as a basis for determining whether the obstacle is a liquid surface or ground.

[0058] S40: Obtain the target spectrum based on the narrow beam spectrum, and calculate the distance between the obstacle and the detection device based on the target spectrum.

[0059] The target spectrum can be obtained by transforming or evolving the narrow beam spectrum. The frequency difference between the narrow beam detection signal and the narrow beam echo signal at the same time can be obtained from the target spectrum. Then, the time delay corresponding to the frequency difference (the time delay of the narrow beam echo signal relative to the narrow beam transmission signal) can be derived, thereby calculating the distance between the obstacle and the detection device.

[0060] In the above embodiments, both wide-beam and narrow-beam detection signals are transmitted, simultaneously obtaining both wide-beam and narrow-beam echo signals. When the obstacle is ground, both wide-beam and narrow-beam spectrum curves are relatively smooth, with energy concentrated in the high and low frequencies. When the obstacle is water, both wide-beam and narrow-beam spectrum curves are relatively steep, with energy concentrated in the mid-frequency range. By combining the wide-beam and narrow-beam spectra, it is possible to determine whether the obstacle is ground or liquid, and simultaneously detect the distance between the obstacle and the detection device, making the radar liquid surface detection device applicable to a wider range of application scenarios.

[0061] In one embodiment of this application, the detection angle of the wide-beam detection signal is greater than or equal to 40°, and the detection angle of the narrow-beam detection signal is less than or equal to 60°, and the detection angle of the wide-beam detection signal is greater than the detection angle of the narrow-beam detection signal. For example, the detection angle of the wide-beam detection signal is 60°, 50°, 45°, etc., and the detection angle of the narrow-beam detection signal is 40°, 35°, 30°, etc.; or, the detection angle of the wide-beam detection signal is 40°, 35°, 30°, etc., and the detection angle of the narrow-beam detection signal is 29°, 25°, 23°, etc.

[0062] In one embodiment of this application, specifically in S10, the waveforms of the narrow beam detection signal and the narrow beam echo signal are specifically described.

[0063] Please see Figure 2 The narrow-beam detection signal can be expressed as S1(t) = A1cos(2πf1t + Φ). o The corresponding narrow-beam echo signal is S2(t)=A2cos(2πf2t+Φ). o ), where t is time, Φ o Let f1 be the initial phase, f2 be the frequency of the narrow-beam detection signal, and f1 be the frequency of the narrow-beam echo signal. For example... Figure 2 As shown, the magnitudes of both f1 and f2 change linearly with time, f1 = f 10 +kt,f1=f 11 +kt,f 10f is the initial frequency of the narrow beam detection signal. 11 Let k be the initial frequency of the narrow-beam echo signal, and k be the slope of the frequency change over time. Figure 2 The slope of the curve. Figure 2 In this context, Δf represents the frequency difference between the narrow-beam detection signal and the narrow-beam echo signal at the same moment. This Δf allows us to calculate the time delay τ between the narrow-beam detection signal and the narrow-beam echo signal, thus enabling us to determine the distance between the obstacle and the detection device. The narrow-beam detection signal and the wide-beam detection signal are the same, and will not be described further here.

[0064] In one embodiment of this application, specifically in S20, the wide-beam detection signal, wide-beam echo signal, narrow-beam detection signal, and narrow-beam echo signal are processed to obtain the wide-beam spectrum and narrow-beam spectrum, respectively. The process of obtaining the wide-beam spectrum and narrow-beam spectrum is similar; here, the narrow-beam spectrum is described in detail, while the wide-beam spectrum will not be repeated. Specifically, the signal processing involves mixing the narrow-beam detection signal and the narrow-beam echo signal, then performing low-pass filtering to obtain a difference frequency signal. The difference frequency signal is sampled, and the sampled data is subjected to Fourier transform to form the narrow-beam spectrum. It should be noted that, ideally, the spectrum is a vertical line, and its corresponding frequency is the aforementioned Δf. However, due to factors such as unevenness of the obstacle surface, interference during signal propagation, and energy loss, the spectrum is generally a curve with a high center and low sides.

[0065] The narrow-beam detection signal and the narrow-beam echo signal are mixed by multiplying S1(t) and S2(t) to obtain the following formula, where Φ is assumed to be... o =0,

[0066] S1(t)S2(t)=A1A2cos(2πf1t)cos(2πf2t)=0.5A1A2[cos2π(f1+f2)t+cos2π(f1-f2)t],

[0067] Low-pass filtering is performed, which means removing high-frequency signals through devices such as low-pass filters. Specifically, the signal of 0.5A1A2cos2π(f1+f2)t is removed, and only the difference frequency signal of 0.5A1A2cos2π(f1-f2)t is retained. This difference frequency signal is sampled, and the sampled data is Fourier transformed to form a narrow beam spectrum.

[0068] In one embodiment of this application, specifically in S30, please refer to... Figure 3 Based on the wide-beam spectrum and narrow-beam spectrum, the obstacle is determined to be either ground or liquid surface, including:

[0069] Determine whether both the wide-beam spectrum and the narrow-beam spectrum are symmetrical structures;

[0070] If so, then the obstacle is determined to be a liquid surface;

[0071] If not, then the obstacle is determined to be water.

[0072] Please see Figure 5 When the obstacle is a liquid surface, both the wide-beam and narrow-beam spectra are symmetrical, meaning they have energy peaks at mid-frequency and symmetrical energy distributions at low and high frequencies, approximating a normal distribution. When the obstacle is ground, more energy is distributed at low frequencies, corresponding to... Figure 6 In the middle, the curves for wide-beam spectrum and narrow-beam spectrum are steeper on the left and flatter on the right.

[0073] In one embodiment of this application, it is determined whether both the wide-beam spectrum and the narrow-beam spectrum are symmetrical structures; if so, the obstacle is determined to be a liquid surface; if not, it is determined whether the slope of the curves of the wide-beam spectrum and the narrow-beam spectrum to the left of the energy peak is greater than the slope to the right of the energy peak; if the slope of the curves of the wide-beam spectrum and the narrow-beam spectrum to the left of the energy peak is greater than the slope to the right of the energy peak, the obstacle is determined to be the ground; if the slope of the curves of the wide-beam spectrum and the narrow-beam spectrum to the left of the energy peak is not greater than the slope to the right of the energy peak, the obstacle is determined not to be the ground.

[0074] In one embodiment of this application, specifically in S30, please refer to... Figure 4 Based on the wide-beam spectrum and narrow-beam spectrum, the obstacle is determined to be either ground or liquid surface, including:

[0075] The wide beam spectrum has a first energy peak and a first energy amplitude. The difference between the first energy peak and the first energy amplitude is a first predetermined difference C1. The two frequency points corresponding to the first energy amplitude are the first frequency point and the second frequency point, and the sum of the energy amplitudes between the first frequency point and the second frequency point is B1.

[0076] The narrow beam spectrum has a second energy peak, a second energy amplitude, and a third energy amplitude. The difference between the second energy peak and the second energy amplitude is a first predetermined difference C1. The two frequency points corresponding to the second energy amplitude are the third frequency point and the fourth frequency point. The sum of the energy amplitudes between the third frequency point and the fourth frequency point is B2. The difference between the second energy peak and the third energy amplitude is a second predetermined difference C2. The second predetermined difference C2 is greater than the first predetermined difference C1. The two frequency points corresponding to the third energy amplitude are the fifth frequency point and the sixth frequency point. The sum of the energy amplitudes between the fifth frequency point and the sixth frequency point is B3.

[0077] Determine if (B3-B2) / B1 is greater than 10%;

[0078] If so, then the obstacle is determined to be a liquid surface;

[0079] If not, then the obstacle is determined to be the ground.

[0080] Specifically, please refer to Figure 5 The wide-beam spectrum has a first energy peak, which is the peak value in the wide-beam spectrum curve, i.e., the maximum energy amplitude. Within the wide-beam spectrum, the first energy amplitude corresponds to two frequency points: the first frequency point and the second frequency point. The sum of the energy amplitudes between the first and second frequency points is B1. The difference between the first energy peak and the first energy amplitude is a first predetermined difference C1. By calculating the sum of the energy B1 between the first and second frequency points, the influence of interference fluctuations on the test results at a specific frequency point can be eliminated, avoiding situations where taking the energy amplitude at a particular frequency point would result in a large error.

[0081] The narrow-beam spectrum has a second energy peak, and the first energy peak is the peak value in the narrow-beam spectrum curve, i.e., the maximum energy amplitude. The second energy amplitude corresponds to two frequency points, namely the third and fourth frequency points. The sum of the energy amplitudes between the third and fourth frequency points is B2, and the difference between the first energy peak and the first energy amplitude is also a first predetermined difference C1. Simultaneously, after reducing the first and second energy peaks by the same amount (the first predetermined difference C1), the sum of the energy amplitudes between the two frequency points is calculated, thus creating an effective comparison of energy amplitudes between the wide-beam and narrow-beam spectra. The third energy amplitude corresponds to two frequency points, namely the fifth and sixth frequency points. The difference between the second energy peak and the third energy amplitude is a second predetermined difference C2, which is greater than the first predetermined difference C1. The sum of the energy amplitudes between the fifth and sixth frequency points is B3, which is greater than B2.

[0082] The obstacle is determined to be either a liquid surface or the ground by checking if (B3-B2) / B1 is greater than 10%. B3-B2 is used in the calculation because energy amplitudes within the B2 range could still be strong reflection points. Including energy amplitudes within the B2 range would result in similar (B3-B2) / B1 ratios, leading to inaccurate results.

[0083] Optionally, the first predetermined difference C1 is 2dB to 6dB, for example, 3dB, 4dB, 5dB, etc. The second predetermined difference C2 is 8dB to 13dB, for example, 9dB, 10dB, 12dB, etc.

[0084] In one embodiment of this application, specifically in S40, the target spectrum is obtained based on the narrow beam spectrum. Optionally, the target spectrum is the narrow beam spectrum, that is, the distance between the obstacle and the detection device is directly calculated based on the narrow beam spectrum.

[0085] In one embodiment of this application, specifically in S40, obtaining the target spectrum based on the narrow beam spectrum includes:

[0086] The target spectrum is an equivalent narrow beam spectrum. After determining that the obstacle is a liquid surface and before calculating the distance between the obstacle and the detection device, the narrow beam detection signal and the narrow beam echo signal are processed to obtain a narrow beam symmetrical spectrum. The narrow beam symmetrical spectrum has a unique energy peak A, and the function corresponding to the narrow beam symmetrical spectrum is F1.

[0087] The narrow beam spectrum has a second energy peak and a fourth energy amplitude. The difference between the second energy peak and the fourth energy amplitude is a third predetermined difference. The two frequency points corresponding to the fourth energy amplitude are the seventh frequency point and the eighth frequency point, respectively. The average value of the energy amplitude between the seventh frequency point and the eighth frequency point is B4.

[0088] The function corresponding to the equivalent narrow beam spectrum is (B4 / A)F2.

[0089] After determining that the obstacle is a liquid surface, in actual testing, the liquid surface may be in a fluctuating state. Therefore, under fluctuating liquid surface conditions, the narrow beam spectrum is not... Figure 5 The spectrum of the standard, and for Figure 6 The corresponding spectrum diagram. Therefore, according to... Figure 6 The distance between the obstacle and the detection device calculated from the spectrum diagram may not be accurate. By taking the above steps to obtain an equivalent narrow beam spectrum and eliminating the influence of liquid surface fluctuations on the detection results as much as possible, the measurement results can be made more accurate.

[0090] Specifically, please refer to Figure 6 Based on the narrow-beam detection signal and the narrow-beam echo signal, a narrow-beam symmetrical spectrum is obtained after signal processing. The signal processing steps in this step are the same as those in S20. Due to liquid surface fluctuations, the narrow-beam spectrum acquired at each moment is different. However, before or during liquid surface fluctuations, there is always a moment when the liquid surface is calm. The narrow-beam spectrum acquired in this calm state is the narrow-beam symmetrical spectrum (e.g., ...). Figure 5 The narrow-beam symmetrical spectrum is the spectrum under ideal conditions. Using this spectrum as a reference, the equivalent narrow-beam spectrum can be obtained. The function corresponding to the narrow-beam symmetrical spectrum is F1, and the energy peak value of the narrow-beam symmetrical spectrum is A.

[0091] The second energy peak and the fourth energy amplitude are obtained based on the actual narrow beam spectrum. The difference between the second energy peak and the fourth energy amplitude, a predetermined third difference, can be 2dB to 6dB, such as 3dB, 4dB, 5dB, etc. The two frequency points corresponding to the fourth energy amplitude are the seventh and eighth frequency points, respectively. The average value of the energy amplitude between the fifth and sixth frequency points is B4. Due to the liquid surface movement, the amplitude corresponding to any frequency point between the fifth and sixth frequency points cannot reflect the actual liquid surface height (the distance between the liquid surface and the obstacle) under real conditions, so the average value B4 is used for equivalence. The function corresponding to the equivalent narrow beam spectrum is (B4 / A)F1.

[0092] In one embodiment of this application, specifically in S40, calculating the distance between the obstacle and the detection device based on the target spectrum includes: obtaining the target frequency of the target spectrum (…). Figure 2 The time edge τ corresponding to the target frequency is calculated using Δf, and the distance R between the obstacle and the detection device is R = 0.5τc, where c is the speed of light.

[0093] Optionally, the target frequency may be the frequency corresponding to the energy peak of the target spectrum, that is, the peak frequency of the target spectrum, such as the peak frequency of the narrow beam spectrum, or the peak frequency of the equivalent narrow beam spectrum.

[0094] Alternatively, the target frequency can also be obtained by the following method: Based on the fact that the target spectrum has a first frequency and a second frequency on both sides of its peak frequency, perform chirp-Z spectrum refinement on the frequency band between the first and second frequencies. The frequency at the point of maximum amplitude index in the refined spectrum is the target frequency. The chirp-Z transform is a special form of the Z-transform. The advantage of this algorithm is that it can refine any chosen frequency band, calculate a more accurate difference frequency signal, and greatly improve ranging accuracy.

[0095] This application also provides a millimeter-wave radar liquid level detection device, which includes: a millimeter-wave antenna, at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor. When the processor executes the computer program, it implements the steps in any of the above-described method embodiments. The millimeter-wave antenna is used to emit wide-beam detection signals and narrow-beam detection signals, and to receive wide-beam echo signals and narrow-beam echo signals, etc.

[0096] The memory can be used to store software programs and modules. The processor executes various functions and data processing of the mobile phone by running the software programs and modules stored in the memory. The memory can mainly include a program storage area and a data storage area. In addition, the memory can include high-speed random access memory, and can also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0097] The processor is the control center of the radar liquid level detection device. It connects to various parts of the device via various interfaces and lines, and performs various functions and processes data by running or executing software programs and / or modules stored in memory, as well as calling data stored in memory, thereby providing overall monitoring of the mobile phone. Optionally, the processor may include one or more processing units.

[0098] The processor can include one or more processors such as a central processing unit (CPU) and a baseband processor. The processor can generate operation control signals based on instruction opcodes and timing signals to control instruction fetching and execution. The memory can be used to store executable program code, including instructions. The processor executes various functional applications and data processing of the network device by running the instructions stored in the memory. The memory can include a program storage area and a data storage area, such as storing data for audio signals to be played. For example, the memory can be Double Data Rate Synchronous Dynamic Random Access Memory (DDR) or Flash memory.

[0099] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps described in the various method embodiments above.

[0100] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0101] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0102] In the embodiments provided in this application, it should be understood that the disclosed apparatus / network devices and methods can be implemented in other ways. For example, the apparatus / network device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0103] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0104] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A millimeter-wave radar method for detecting liquid levels, characterized in that, include: It transmits wide-beam detection signals and narrow-beam detection signals, and receives wide-beam echo signals and narrow-beam echo signals formed after reflection from obstacles, wherein the detection angle of the wide-beam detection signal is greater than the detection angle of the narrow-beam detection signal; Based on the wide beam detection signal, the wide beam echo signal, the narrow beam detection signal, and the narrow beam echo signal, after signal processing, the wide beam spectrum and the narrow beam spectrum are obtained respectively. Based on the wide beam spectrum and the narrow beam spectrum, the obstacle is determined to be either ground or liquid surface; The target spectrum is obtained based on the narrow beam spectrum, and the distance between the obstacle and the detection device is calculated based on the target spectrum. Determining whether the obstacle is ground or liquid surface based on the wide-beam spectrum and the narrow-beam spectrum includes: The wide beam spectrum has a first energy peak and a first energy amplitude, the difference between the first energy peak and the first energy amplitude is a first predetermined difference, the two frequency points corresponding to the first energy amplitude are a first frequency point and a second frequency point, and the sum of the energy amplitudes between the first frequency point and the second frequency point is B1; The narrow beam spectrum has a second energy peak, a second energy amplitude, and a third energy amplitude. The difference between the second energy peak and the second energy amplitude is a first predetermined difference. The two frequency points corresponding to the second energy amplitude are the third frequency point and the fourth frequency point. The sum of the energy amplitudes between the third frequency point and the fourth frequency point is B2. The difference between the second energy peak and the third energy amplitude is a second predetermined difference. The second predetermined difference is greater than the first predetermined difference. The two frequency points corresponding to the third energy amplitude are the fifth frequency point and the sixth frequency point. The sum of the energy amplitudes between the fifth frequency point and the sixth frequency point is B3. Determine if (B3-B2) / B1 is greater than 10%; If so, then the obstacle is determined to be a liquid surface; If not, then the obstacle is determined to be the ground; Alternatively, determining whether the obstacle is ground or liquid surface based on the wide-beam spectrum and the narrow-beam spectrum includes: Determine whether both the wide-beam spectrum and the narrow-beam spectrum are symmetrical structures; If so, then the obstacle is determined to be a liquid surface; If not, then the obstacle is determined to be water.

2. The millimeter-wave radar liquid level detection method as described in claim 1, characterized in that, The first predetermined difference is 2dB to 6dB, and the second predetermined difference is 8dB to 13dB.

3. The millimeter-wave radar liquid level detection method as described in claim 1, characterized in that, Obtaining the target spectrum based on the narrow beam spectrum includes: The target spectrum is the narrow beam spectrum; or... The target spectrum is an equivalent narrow-beam spectrum. After determining that the obstacle is a liquid surface and before calculating the distance between the obstacle and the detection device, a narrow-beam symmetrical spectrum is obtained after signal processing based on the narrow-beam detection signal and the narrow-beam echo signal. The narrow-beam symmetrical spectrum has an energy peak A, and the function corresponding to the narrow-beam symmetrical spectrum is... F 1; The narrow beam spectrum has a second energy peak and a fourth energy amplitude. The difference between the second energy peak and the fourth energy amplitude is a third predetermined difference. The two frequency points corresponding to the fourth energy amplitude are the seventh frequency point and the eighth frequency point, respectively. The average value of the energy amplitude between the seventh frequency point and the eighth frequency point is B4. The function corresponding to the equivalent narrow beam spectrum is (B4 / A). F 1.

4. The millimeter-wave radar liquid level detection method as described in claim 1, characterized in that, The distance between the obstacle and the detection device is calculated based on the target spectrum, including: Obtain the target frequency of the target spectrum and calculate the time edge corresponding to the target frequency. The distance R between the obstacle and the detection device is 0.

5. c, where c is the speed of light.

5. The millimeter-wave radar liquid level detection method as described in claim 4, characterized in that, The target frequency is the peak frequency of the target spectrum; or, The target spectrum has a first frequency and a second frequency on both sides of its peak frequency. The frequency band between the first frequency and the second frequency is refined by chirp-Z spectrum refinement. The frequency at which the index of the maximum amplitude of the refined spectrum is located is the target frequency.

6. The millimeter-wave radar liquid level detection method according to any one of claims 1-5, characterized in that, The detection angle of the wide-beam detection signal is greater than or equal to 40º, and the detection angle of the narrow-beam detection signal is less than or equal to 60º.

7. A millimeter-wave radar liquid level detection device, comprising a millimeter-wave antenna for transmitting and receiving signals, a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method as described in any one of claims 1 to 6.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 6.

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