Soil moisture content testing method based on transmission parameters

Abstract

The invention discloses a soil moisture content testing method based on transmission parameters, belongs to the technical field of soil moisture content testing, and solves the problem that an existing soil moisture content testing method utilizing electromagnetic wave propagation cannot accurately perform early warning on geological disasters due to fewer measuring paths. According to the invention, an antenna array is created by 2 # imgabs0 # amplitude dual antennas on two antenna mounting columns, soil information is obtained from different angles and depths through a # imgabs1 # combination mode, multi-path measurement is realized, and a calibrated soil moisture content distribution soil layer closest to a monitored soil layer is more conveniently judged through multi-path measurement, so that the measurement accuracy is improved, and the measurement accuracy is improved. According to the method, the soil moisture content is calibrated to be distributed in the soil layer, a reference value set for a calibration experiment is calibrated, complex and changeable conditions of an actually monitored soil layer are considered, the calibrated experiment soil layer has higher robustness, continuity and stability of monitoring work are guaranteed, and experts can conveniently evaluate an accurate geological disaster early warning grade.

Description

Technical Field

[0001] The present invention relates to the technical field of soil moisture testing, and in particular to a soil moisture testing method based on transmission parameters. Background Art

[0002] Soil moisture content, the amount of water per unit volume or weight of soil, is a key factor influencing plant growth, soil physical properties, and ecological processes. Accurately measuring soil moisture is crucial for agricultural irrigation management, water resource conservation, environmental protection, and geological disaster early warning.

[0003] Existing methods for measuring soil moisture often rely on electromagnetic wave propagation and reflection. The principle is that a transmitting antenna sends electromagnetic waves of a specific frequency into the soil, while a receiving antenna collects the waves reflected from the soil surface or internal structure. Because the dielectric constant of the soil medium changes with moisture content, this affects the propagation speed, attenuation, and reflection characteristics of the electromagnetic waves within the soil. By analyzing parameters such as the time delay, amplitude, and phase of the reflected wave, information about the soil moisture content can be extracted.

[0004] For example, patent application CN115684213A discloses a non-contact, multi-layer soil moisture measurement method and device, which includes: arranging transmitting and receiving antennas for wireless radio frequency signals; scanning the signal at equal intervals within a certain frequency range, estimating the channel frequency response, and using an inverse Fourier transform to obtain a power delay distribution time domain signal, from which the reflection signal is extracted; checking the phase difference between adjacent receiving antenna signals, setting a threshold for signal filtering, and discarding reflection signals from non-soil layers; using an iterative method to jointly estimate the filtered reflection signals to determine the depth of each soil layer and the wavelength of the reflection signal passing through each soil layer; and calculating the moisture content of each soil layer. Although this invention can non-contactly calculate the moisture content of each soil layer, soil structure is generally not uniform, and soil composition, density, and particle size distribution at different locations may vary significantly. This results in different responses to wireless radio frequency signals even within the same soil layer. As a result, due to the limited number of measurement paths, this measurement method cannot accurately obtain soil moisture content in complex soil environments, thus failing to provide accurate early warning of geological disasters. Summary of the Invention

[0005] In response to the above-mentioned problems in the prior art, the present invention provides a soil moisture testing method based on transmission parameters, which solves the problem that the existing soil moisture testing method using electromagnetic wave propagation cannot accurately provide early warning of geological disasters due to the lack of measurement paths.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A soil moisture content testing method based on transmission parameters is provided, comprising the steps of: S1, set both The antenna mounting poles of the dual antennas are fixed symmetrically in the monitoring soil and The dual antennas are electrically connected to the detection circuit through a matrix switch. is a natural number greater than or equal to 3; S2, through the detection circuit The dual antennas are sorted and numbered, and divided into groups of two by two. A set of measurement antennas, and the two dual antennas of each set of measurement antennas are used as the transmitting antenna and the receiving antenna of the detection circuit respectively; S3, the signal frequency of the signal generator in the detection circuit is set to multiple different characteristic frequencies in sequence to obtain the measurement data of the monitored soil layer, the measurement data includes and ,in For the At the characteristic frequency, The dual antenna No. is the transmitting antenna and the The fast Fourier transform calculation result of the output data of the in-phase analog-to-digital converter in the detection circuit is obtained when the dual antenna is the receiving antenna; In the At the characteristic frequency, The dual antenna No. is the transmitting antenna and the The fast Fourier transform calculation result of the output data of the orthogonal analog-to-digital converter in the detection circuit is obtained when the dual antenna is the receiving antenna; S4. Calculate the comparison fitting factor between the measured data and the calibration data ; Calibration data includes and , For the In the calibrated soil moisture distribution soil layer, At the characteristic frequency, The dual antenna No. is the transmitting antenna and the The fast Fourier transform calculation result of the in-phase analog-to-digital converter output data is obtained when the dual antenna is the receiving antenna; For the The soil moisture content distribution of the first soil layer At the characteristic frequency, The dual antenna No. is the transmitting antenna and the The fast Fourier transform calculation result of the orthogonal analog-to-digital converter output data obtained when the dual antenna is the receiving antenna; For the Calibrated soil moisture distribution layer, At the characteristic frequency, The dual antenna No. is the transmitting antenna and the When the dual antenna is the receiving antenna, and Comparison fitting factor with calibration data; S5. According to The maximum value of the comprehensive correlation factor between the measurement data and the calibration data is calculated, and the calibration soil moisture distribution layer corresponding to the maximum value of the comprehensive correlation factor is used as the actual soil moisture distribution layer of the monitoring soil layer; S6. Based on the actual soil moisture content, soil layer distribution and geological structure of the monitored soil layer, the geological disaster warning level of the monitored soil layer is given by expert evaluation.

[0007] In this solution, since each set of measurement antennas can be used as a transmitting and receiving unit independently, the reflected signals under different paths can be obtained by changing the combination of transmitting and receiving antennas. A dual antenna creates a virtual antenna array by This combination method can obtain soil information from different angles and depths, and realize multi-path measurement. Multi-path measurement can obtain information at different depths at the same time, thereby more accurately reflecting the trend of soil moisture content changing with depth, and is suitable for complex soil environments. At the same time, if the data of a specific path in the multi-path measurement is abnormal, it can be corrected by the data of other paths. This solution can obtain the real and imaginary part information of the transmitted signal respectively through the in-phase analog-to-digital converter and the orthogonal analog-to-digital converter, and then perform a fast Fourier transform on these data, which helps to convert the time domain signal into a frequency domain signal, thereby better analyzing the signal characteristics, and can more accurately capture the relationship between the electromagnetic wave propagation characteristics in the soil and the soil moisture content. The data set formed by the combination is not only large in number, but also more convenient for determining the calibrated soil moisture distribution layer that is closest to the monitored soil layer. The calibrated soil moisture distribution layer is the benchmark value set for the calibration experiment. Taking into account the complex and changeable conditions of the actual monitored soil layer, the calibration experimental soil layer has stronger robustness. Even when the environmental conditions change, the strategy can be quickly adjusted by comparing the calibration data to ensure the continuity and stability of the monitoring work, which is convenient for experts to assess the accurate geological disaster warning level.

[0008] Furthermore, the antenna mounting post includes a hollow housing with an open top. The housing's front projection forms an inverted triangle, and both sides of the housing are curved. Multiple antenna holes are symmetrically defined along the housing's central axis on the two curved walls of the housing. The interior of the housing is filled with an antenna insulation layer, and multiple antennas are symmetrically positioned within the antenna insulation layer. The bottom ends of the multiple antennas extend through the multiple antenna holes on the two curved walls and contact the monitored soil, while the top ends of the multiple antennas are electrically connected to the detection circuit. The two antennas, positioned at the same height on the two curved walls, form a dual antenna. The curved surfaces of the housing facilitate good contact between the antenna and the soil, and the antenna insulation layer protects the internal components from environmental influences, thereby improving measurement accuracy and stability. The two antennas, positioned at the same height on the two curved walls, form a dual antenna, utilizing the mutual cancellation characteristics of the dual antenna design to help reduce electromagnetic interference from the external environment.

[0009] Furthermore, the multiple antenna holes on the two curved walls are evenly spaced along the height of the housing. Each pair of antennas operates at a specific height, providing data about that layer of soil. When multiple antennas are vertically distributed, a three-dimensional spatial model is constructed, improving the spatial resolution of the soil's internal structure.

[0010] Furthermore, the antenna insulation layer includes multiple guide holes for guiding and securing the antenna. These guide holes correspond to the antenna holes in a one-to-one relationship. The bottom of each guide hole is curved and connected to the corresponding antenna hole. The diameter of each guide hole is smaller than that of the corresponding antenna hole. This arrangement ensures the antenna is properly installed and maintains a stable position, preventing external interference. Furthermore, the smaller diameter of the guide holes prevents contact between the antenna and the housing, ensuring electrical isolation and reducing interference and noise.

[0011] Furthermore, each antenna mounting post has The dual antennas are electrically connected to the detection circuit through a matrix switch. The matrix switch is set so that each antenna mounting post The dual antennas can be used as transmitting antennas or receiving antennas, increasing the measurement path.

[0012] Furthermore, the detection circuit includes a microprocessor equipped with a communication interface. The microprocessor is sequentially connected to a signal generator, a sinusoidal signal power splitter, a transmit mixer, a transmit power amplifier, and a transmit antenna interface connected to a matrix switch. The transmit mixer is connected to the microprocessor via a digital-to-analog converter. The sinusoidal signal power splitter is also connected to an orthogonal demodulator, which is respectively connected to an in-phase analog-to-digital converter, an orthogonal analog-to-digital converter, and a receive antenna interface. The in-phase analog-to-digital converter and the orthogonal analog-to-digital converter are both connected to the microprocessor. The detection circuit is capable of performing efficient signal processing and analysis, and realizing data acquisition and fast Fourier transform.

[0013] Furthermore, the quadrature demodulator includes a coupler connected to the sinusoidal signal power splitter. One output of the coupler is sequentially connected to an in-phase mixer, an in-phase low-noise amplifier, and a in-phase analog-to-digital converter. The other output of the coupler is sequentially connected to a quadrature mixer, a quadrature low-noise amplifier, and a quadrature analog-to-digital converter. Both the in-phase mixer and the quadrature mixer are connected to a receiving power splitter, which is connected to a receiving antenna interface via a receiving low-noise amplifier. The microprocessor is signal-connected to a remote monitoring terminal via a communication interface, which is used to send test instructions and receive data. The remote monitoring terminal features remote control and data transmission capabilities, allowing users to monitor and manage the test process in real time, while also facilitating subsequent data analysis and report generation.

[0014] Furthermore, the method for obtaining the characteristic frequency is: SA, create multiple calibrated soil moisture distribution soil layers with different soil moisture; SB, through two symmetrically set antenna mounting poles, measure all the calibration soil moisture distribution soil layers in turn, and get and ; For the In the calibrated soil moisture distribution layer, the frequency of the detection circuit is , No. The dual antenna No. is the transmitting antenna and the The fast Fourier transform calculation result of the output data of the in-phase analog-to-digital converter in the detection circuit is obtained when the dual antenna is the receiving antenna; For the In the calibrated soil moisture distribution layer, the frequency of the detection circuit is , No. The dual antenna No. is the transmitting antenna and the When the dual antenna is the receiving antenna, the fast Fourier transform calculation result of the orthogonal analog-to-digital converter output data is obtained; SC, calculate the comprehensive fitting factor, the calculation method is:

[0015]

[0016] in, For the Calibrated soil moisture distribution layers and frequencies The comprehensive fitting factor between is the fitting factor; The sampling point of the in-phase analog-to-digital converter is In the case of indivual The value of For middle The value of the variable constant The corresponding value when for middle The corresponding value when the value of is 1; The sampling point of the quadrature analog-to-digital converter is In the case of indivual The value of for The value in is a variable constant The corresponding value when for middle The corresponding value when the value of is 1; The value range is ), B is the total number of soil layers with set calibration soil moisture content distribution; SD, in Within the value range, gradually calculate each Corresponding , and in the corresponding The maximum value is obtained from the B maximum values, and the B frequencies corresponding to the comprehensive fitting factors of the B maximum values ​​are respectively used as B calibrated soil moisture distribution soil layer characteristic frequencies.

[0017] In this approach, by calculating the comprehensive fitting factor at different frequencies and selecting the frequency corresponding to the maximum value as the characteristic frequency, we ensure that the selected frequency is the key frequency that best reflects changes in soil moisture content. This helps optimize signal selection and makes subsequent data analysis more accurate and effective. Furthermore, because it considers the calibration of soil moisture distribution layers under various humidity conditions and obtains information through multipath measurement, this method is particularly suitable for situations with complex soil structure and uneven composition, improving its applicability to soil moisture measurement in complex soil environments.

[0018] Furthermore, the comparison of fitting factors The calculation method is:

[0019] in, The sampling point of the in-phase analog-to-digital converter is In the case of indivual The value of For middle The value of The value at the characteristic frequency; The sampling point of the quadrature analog-to-digital converter is In the case of indivual The value of for middle The value of The value at the characteristic frequency.

[0020] In this approach, the similarity between measured and calibrated data can be quantified by calculating the comparative fit factor. This helps determine soil moisture content more accurately, especially in complex soil environments where changes in soil structure and composition can lead to changes in electromagnetic wave propagation characteristics. The comparative fit factor can help identify the data that most closely resembles the actual situation.

[0021] Furthermore, the calculation method of the comprehensive correlation factor is:

[0022]

[0023]

[0024] in, For the A comprehensive correlation factor between the calibrated soil moisture distribution layer and the measured data; For the A factor for the same soil layer as the measured data for the calibrated soil moisture distribution; For the A calibrated soil moisture distribution soil layer and different soil layer factors of the measured data; The value range is ), B is the total number of soil layers for the calibration soil moisture distribution.

[0025] In this scheme, by comprehensively considering the factors of the same soil layer and the factors of different soil layers, the matching between the measured data and the calibration data can be comprehensively evaluated, which helps to determine the calibration soil moisture distribution layer that is closest to the monitored soil layer.

[0026] The present invention discloses a soil moisture content testing method based on transmission parameters, which has the following beneficial effects: The present invention is to install two antennas on the poles The dual antenna creates an antenna array by This combination method realizes the acquisition of soil information from different angles and depths, and realizes multi-path measurement. Multi-path measurement makes it easier to determine the calibration soil moisture distribution layer that is closest to the monitored soil layer. The calibration soil moisture distribution layer is the benchmark value set for the calibration experiment. Taking into account the complex and changeable conditions of the actual monitored soil layer, the calibration experimental soil layer has stronger robustness. Even when the environmental conditions change, the strategy can be quickly adjusted by comparing the calibration data to ensure the continuity and stability of the monitoring work, which is convenient for experts to assess the accurate geological disaster warning level. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Side view of the mounting pole for the two antennas; Figure 2 A top view of the two antenna mounting poles; Figure 3 This is a top view of an antenna mounting pole; Figure 4 Schematic diagram of the structure of the shell; Figure 5 A side view of an antenna mounting post; Figure 6 Schematic diagram of the structure of the introduction hole; Figure 7 This is a front view of an antenna mounting post; Figure 8 This is a schematic diagram of the connection between the antenna and the detection circuit through the matrix switch; Figure 9 It is a structural diagram of the detection circuit; Figure 10 This is the circuit diagram of the signal generator; Figure 11 Circuit diagram of the digital-to-analog converter Figure 12 This is the circuit diagram of the mixer; Figure 13 This is the circuit diagram of the transmitting power amplifier; Figure 14 This is the circuit diagram of the receiving low noise amplifier; Figure 15 This is the circuit diagram of the analog-to-digital converter; Figure 16 This is the circuit diagram of the matrix switch; Figure 17 is the circuit diagram of the quadrature demodulator; Among them: 1. Shell; 3. Antenna insulation layer; 11. Detection circuit; 13. Signal generator; 14. Digital-to-analog converter; 15. Microprocessor; 16. Communication interface; 17. Sine signal power splitter; 18. Coupler; 19. Phase shifter; 20. Transmit mixer; 21. Receive power splitter; 22. In-phase mixer; 23. Quadrature mixer; 24. Transmit power amplifier; 25. Receive low-noise amplifier; 26. In-phase low-noise amplifier; 27. Quadrature low-noise amplifier; 28. Transmit antenna interface; 29. ​​Receive antenna interface; 30. In-phase analog-to-digital converter; 31. Quadrature analog-to-digital converter; 32. Quadrature demodulator. DETAILED DESCRIPTION

[0028] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0029] This embodiment provides a soil moisture testing method based on transmission parameters. Its purpose is to solve the problem that the existing soil moisture testing method using electromagnetic wave propagation cannot be applied to complex soil environments due to the limited measurement paths. It will be demonstrated in detail below.

[0030] A soil moisture content testing method based on transmission parameters comprises the following steps: S1, set both The antenna mounting poles of the dual antennas are fixed symmetrically in the monitoring soil and The dual antennas are electrically connected to the detection circuit through a matrix switch. is a natural number greater than or equal to 3.

[0031] S2, through the detection circuit The dual antennas are sorted and numbered, and divided into groups of two by two. The system uses two pairs of measuring antennas, each serving as the transmitting and receiving antennas of the detection circuit. The detection circuit transmits specific electromagnetic waves through the transmitting antenna and receives them through the receiving antenna. The detection circuit then calculates the soil's electromagnetic characteristics, including transmission, reflection, refraction, loss, dispersion, and multiple reflections at interfaces, to determine soil moisture changes.

[0032] The inventors considered that for layered soil or other complex geological structures, single-path measurement often cannot provide sufficient information to describe the state of the entire soil body. Multi-path measurement can obtain information at different depths simultaneously, thereby more accurately reflecting the trend of soil moisture content changing with depth. It is suitable for complex soil environments. Since each set of measurement antennas can independently serve as a transmitting and receiving unit, the reflected signals under different paths can be obtained by changing the combination of transmitting and receiving antennas. Therefore, the inventors fixed the two antenna mounting poles symmetrically and connected the two antenna mounting poles. A dual antenna creates a virtual antenna array by This combination of methods enables soil information to be acquired from different angles and depths, achieving multi-path measurement. Multi-path measurement can simultaneously acquire information at different depths, thereby more accurately reflecting the distribution of soil moisture content and is suitable for complex soil environments.

[0033] S3, the signal frequency of the signal generator 13 in the detection circuit is set to multiple different characteristic frequencies in sequence to obtain the measurement data of the monitored soil layer, the measurement data includes and ,in For the At the characteristic frequency, The dual antenna No. is the transmitting antenna and the The fast Fourier transform calculation result of the output data of the in-phase analog-to-digital converter 30 in the detection circuit is obtained when the dual antenna is the receiving antenna; In the At the characteristic frequency, The dual antenna No. is the transmitting antenna and the The fast Fourier transform calculation result of the output data of the orthogonal analog-to-digital converter 31 in the detection circuit is obtained when the dual antenna is the receiving antenna.

[0034] S4. Calculate the comparison fitting factor between the measured data and the calibration data , For the Calibrated soil moisture distribution layer, At the characteristic frequency, The dual antenna No. is the transmitting antenna and the When the dual antenna is the receiving antenna, and Comparison fitting factor between the calibration data.

[0035] Calibration data includes and , For the In the calibrated soil moisture distribution soil layer, At the characteristic frequency, The dual antenna No. is the transmitting antenna and the The fast Fourier transform calculation result of the output data of the in-phase analog-to-digital converter 30 obtained when the dual antenna is the receiving antenna; For the The soil moisture content distribution of the first soil layer At the characteristic frequency, The dual antenna No. is the transmitting antenna and the The fast Fourier transform calculation result of the output data of the orthogonal analog-to-digital converter 31 is obtained when the dual antenna is the receiving antenna.

[0036] Specifically, the calculation method of the comparative fitting factor is:

[0037] in, The sampling point of the 30-bit analog-to-digital converter is In the case of indivual The value of For middle The value of The value at the characteristic frequency; The sampling point of the quadrature analog-to-digital converter 31 is In the case of indivual The value of for middle The value of The value at the characteristic frequency.

[0038] S5. According to The maximum value of the comprehensive correlation factor between the measurement data and the calibration data is calculated, and the calibration soil moisture distribution layer corresponding to the maximum value of the comprehensive correlation factor is used as the actual soil moisture distribution layer of the monitoring soil layer.

[0039] Specifically, the calculation method of the comprehensive correlation factor is:

[0040]

[0041]

[0042] in, For the A comprehensive correlation factor between the calibrated soil moisture distribution layer and the measured data; For the A factor for the same soil layer as the measured data for the calibrated soil moisture distribution; For the A calibrated soil moisture distribution soil layer and different soil layer factors of the measured data; The value range is ), B is the total number of soil layers for the calibration soil moisture distribution.

[0043] S6. Based on the actual soil moisture content, soil layer distribution and geological structure of the monitored soil layer, the geological disaster warning level of the monitored soil layer is given by expert evaluation.

[0044] This embodiment can obtain the real part and imaginary part information of the transmitted signal respectively through the in-phase analog-to-digital converter 30 and the orthogonal analog-to-digital converter 31, and then perform fast Fourier transform on these data, which helps to convert the time domain signal into a frequency domain signal, thereby better analyzing the signal characteristics and more accurately capturing the relationship between the electromagnetic wave propagation characteristics in the soil and the soil moisture content. The dataset formed by these combinations is not only large in number, but each data point represents the soil properties on a specific path, thus obtaining a higher-resolution soil moisture distribution map.

[0045] Specifically, as the specific structure of the antenna mounting post of this embodiment, the antenna mounting post includes: Housing 1, reference Figures 3 to 5 The housing 1 is a hollow steel structure with an open top. Its front projection forms an inverted triangle, with both sides of the housing 1 being curved. Multiple antenna holes are symmetrically arranged along the central axis of the housing 1 on the two curved walls of the housing 1. The curved surfaces of the housing 1 facilitate good contact between the antenna and the soil, and the provision of the antenna insulation layer 3 protects the internal components from external environmental influences, thereby improving measurement accuracy and stability. The multiple antenna holes on the curved walls are evenly spaced along the height of the housing 1.

[0046] Antenna insulation layer 3, reference Figure 3 The antenna insulation layer 3 is an aluminum-clad steel structure and is filled inside the housing 1. Multiple antennas are symmetrically arranged within the antenna insulation layer 3. The bottom ends of the multiple antennas pass through multiple antenna holes on the curved walls on both sides and contact the monitored soil. The top ends of the multiple antennas are electrically connected to the detection circuit. Among them, the two antennas located at the same height on the curved walls on both sides form a dual antenna. The mutual cancellation characteristics of the dual antenna design can help reduce electromagnetic interference from the external environment.

[0047] In order to facilitate the fixing of the antenna in the antenna insulation layer 3, refer to Figure 6 and Figure 7. A plurality of lead-in holes for guiding and fixing the antenna are provided inside the antenna insulation layer 3, and the plurality of lead-in holes are in a one-to-one correspondence with the plurality of antenna holes. The upper part of each lead-in hole is vertically provided, and the bottom end of each lead-in hole is bent and connected to the corresponding antenna hole, and the diameter of each lead-in hole is smaller than the diameter of the corresponding antenna hole. The provision of the lead-in holes facilitates ensuring that the antenna is correctly installed and maintains a stable position to prevent external interference. At the same time, the diameter of the lead-in hole is smaller than the diameter of the antenna hole, which avoids contact between the antenna and the housing 1, ensures electrical isolation, and reduces interference and noise. In this embodiment, the number of lead-in holes is 8, and the number of antenna holes on each side of the curved wall of the housing 1 is 8. Reference Figure 6 In the figure, 2-L1, 2-L2, 2-L3, 2-L4, 2-R1, 2-R2, 2-R3, and 2-R4 are all antenna introduction holes. Figure 5 , where 4-1, 4-2, 4-3 and 4-4 are antenna holes.

[0048] As a method for fixing the two antenna mounting posts in this embodiment, during installation, the two antenna mounting posts are arranged in parallel, with their tips facing downward, and hammered into the soil. After the antenna mounting posts are hammered in, the tips of the antennas are each hammered in through the introduction holes with their tips facing downward. After the antennas are hammered in, the tips are hammered into the soil and embedded to a certain length, with the tops of the antennas exposed to a certain length. Signal connection cables are welded to the dual antennas exposed above the soil surface, and then the dual antennas exposed above the soil surface and the connection wires between the antennas and the signal connection cables are sealed with a top cover to provide waterproofing.

[0049] In this embodiment, reference Figure 7 , 5-L1, 5-L2, 5-L3, 5-L4, 5-R1, 5-R2, 5-R3, and 5-R4 are all antennas. After installation, 5-L1 and 5-R1 form a dual antenna, and the upper part is the cable connection port of the dual antenna; 5-L2 and 5-R2 form a dual antenna, and the upper part is the cable connection port of the dual antenna; 5-L3 and 5-R3 form a dual antenna, and the upper part is the cable connection port of the dual antenna; 5-L4 and 5-R4 form a dual antenna, and the upper part is the cable connection port of the dual antenna.

[0050] As a specific structure with two antenna mounting poles installed, refer to Figure 1 and Figure 2 .in Figure 1 and Figure 21a and 1b are the outer shell 1 of the mounting column; 3a and 3b are the insulating layers of the mounting column; 4-1a, 4-2a, 4-3a, 4-4a, 4-1b, 4-2b, 4-3b and 4-4b are antenna holes; 5-L1a, 5-L2a, 5-L3a, 5-L4a, 5-L1b, 5-L2b, 5-L3b, 5-L4b, 5-R1a, 5-R2a, 5-R3a, 5-R4a, 5-R1b, 5-R2b, 5-R3b and 5-R4b are antennas; 6A is the left mounting column; 6B is the right mounting column There are four pairs of dual antennas on the left mounting column, as follows: 5-L1a and 5-R1a form a dual antenna TA1; 5-L2a and 5-R2a form a dual antenna TA2; 5-L3a and 5-R3a form a dual antenna TA3; 5-L4a and 5-R4a form a dual antenna TA4; There are four pairs of dual antennas on the right mounting column, as follows: 5-L1b and 5-R1b form a dual antenna TB1; 5-L2b and 5-R2b form a dual antenna TB2; 5-L3b and 5-R3b form a dual antenna TB3; 5-L4b and 5-R4b form a dual antenna TB4; Among them, 10b is connected to the dual antenna TA1, dual antenna TA2, dual antenna TA3, and dual antenna TA4 through a signal connection cable; the dual antenna TA1, dual antenna TA2, dual antenna TA3, and dual antenna TA4 constitute antenna array A; 10b is connected to the dual antenna TB1, dual antenna TB2, dual antenna TB3, and dual antenna TB4 through a signal connection cable; the dual antenna TB1, dual antenna TB2, dual antenna TB3, and dual antenna TB4 constitute antenna array B.

[0051] Connection reference of antenna array A and antenna array B and detection circuit Figure 8 Among them, 8-1a is the dual antenna TA1, 8-2a is the dual antenna TA2, 8-3a is the dual antenna TA3, 8-4a is the dual antenna TA4, 8-1b is the dual antenna TB1, 8-2b is the dual antenna TB2, 8-3b is the dual antenna TB3, and 8-4b is the dual antenna TB4; 9-1a, 9-2a, 9-3a, 9-4a, 9-1b, 9-2b, 9-3b, 9-4b, 9-1c and 9-2c are all signal connection cables; 10a is the matrix switch A, and 10b is the matrix switch B; the matrix switch A and the matrix switch B are both connected to the detection circuit through signal connection cables.

[0052] As a further solution of this embodiment, each antenna mounting post The dual antennas are electrically connected to the detection circuit through a matrix switch. The matrix switch is set so that each antenna mounting post The dual antennas can be used as transmitting antennas or receiving antennas, increasing the measurement path.

[0053] Specifically, the detection circuit can select different antennas in antenna array A as transmitting and receiving antennas through matrix switch A; can also select different antennas in antenna array B as transmitting and receiving antennas through matrix switch B; or can select one antenna in antenna array A as a transmitting antenna through matrix switch A and one antenna in antenna array B as a receiving antenna through matrix switch B; or can select one antenna in antenna array A as a receiving antenna through matrix switch A and one antenna in antenna array B as a transmitting antenna through matrix switch B. Matrix switch A and matrix switch B are both controlled by the detection circuit's microprocessor 15, with commands issued by the detection circuit's microprocessor 15.

[0054] As the specific structure of the detection circuit of this embodiment, refer to Figure 9 The detection circuit includes a microprocessor 15 equipped with a communication interface 16. The microprocessor 15 is sequentially connected to a signal generator 13, a sinusoidal signal power splitter 17, a transmit mixer 20, a transmit power amplifier 24, and a transmit antenna interface 28 connected to a matrix switch. The transmit mixer 20 is connected to the microprocessor 15 via a digital-to-analog converter 14. The sinusoidal signal power splitter 17 is also connected to a quadrature demodulator 32, which is respectively connected to an in-phase analog-to-digital converter 30, a quadrature analog-to-digital converter 31, and a receive antenna interface 29. The in-phase analog-to-digital converter 30 and the quadrature analog-to-digital converter 31 are both connected to the microprocessor 15. The detection circuit can perform efficient signal processing and analysis, and realize data acquisition and fast Fourier transform.

[0055] The microprocessor 15 communicates with the detection server through the communication interface 16 and receives commands from the detection server. Under the control of the detection server, the microprocessor 15 sets the signal frequency for the signal generator 13 and the signal format for the analog-to-digital converter 14. The signal from the signal generator 13 is split into two paths by a power splitter. One path, combined with the signal from the analog-to-digital converter 14, passes through a mixer, where the signal from the analog-to-digital converter 14 is multiplied by the signal from the signal generator 13. After amplification by the transmit power amplifier 24, the signal is then connected to the matrix switches A and B via the transmit antenna interface 28. The other path of the signal from the signal generator 13, after passing through the power splitter, is connected to the local oscillator frequency input of the quadrature demodulator 32. The receive antenna interface 29 is connected to the matrix switches A and B. The receive antenna signal is amplified by a low-noise amplifier and then input to the RF input of the quadrature demodulator 32. The in-phase signal demodulated by the quadrature demodulator 32 undergoes analog-to-digital conversion by the in-phase analog-to-digital converter 30, and the data is then sent to the microprocessor 15. The orthogonal signal demodulated by the orthogonal demodulator 32 is converted from analog to digital by the orthogonal analog to digital converter 31 , and the data is sent to the microprocessor 15 .

[0056] As the specific structure of the orthogonal demodulator 32, the orthogonal demodulator 32 includes a coupler 18 connected to the sinusoidal signal power divider 17, one output end of the coupler 18 is connected to the in-phase mixer 22, the in-phase low-noise amplifier 26 and the in-phase analog-to-digital converter 30 in sequence, and the other output end of the coupler 18 is connected to the orthogonal mixer 23, the orthogonal low-noise amplifier 27 and the orthogonal analog-to-digital converter 31 in sequence; wherein, the in-phase mixer 22 and the orthogonal mixer 23 are both connected to the receiving power divider 21, and the receiving power divider 21 is connected to the receiving antenna interface 29 through the receiving low-noise amplifier 25.

[0057] The circuit principle of quadrature demodulator 32 is as follows: the signal from sinusoidal signal power splitter 17 is input to coupler 18, where it is split into two paths: one path is sent to phase shifter 19, and the other path is sent to in-phase mixer 22. Receiver power splitter 21 also splits the signal into two paths: one path is sent to in-phase mixer 22, and the other path is sent to quadrature mixer 23. The output signal of in-phase mixer 22 is sent to in-phase low-noise amplifier 26. The output signal of phase shifter 19 is sent to quadrature mixer 23, and the output signal of quadrature mixer 23 is sent to quadrature low-noise amplifier 27. In-phase low-noise amplifier 26 outputs an in-phase demodulated signal, and quadrature low-noise amplifier 27 outputs a quadrature demodulated signal.

[0058] In this embodiment, the microprocessor 15 is connected to a remote monitoring terminal for sending test instructions and receiving data via a communication interface 16. The remote monitoring terminal has remote control and data transmission capabilities, allowing users to monitor and manage the test process in real time, while also facilitating subsequent data analysis and report generation.

[0059] Under the control of the remote monitoring terminal, microprocessor 15 can set the signal frequency of signal generator 13 and the signal waveform via digital-to-analog converter 14. The signal from signal generator 13 and the signal from analog-to-digital converter 14 are mixed by transmit mixer 20 to generate an arbitrary signal. The generated arbitrary signal is amplified by transmit power amplifier 24 and then transmitted through the transmit antenna.

[0060] As a further solution of this embodiment, under a typical test signal, the microprocessor 15 selects one of the TA1, TA2, TA3, and TA4 antennas as the transmitting antenna; the TB1, TB2, TB3, and TB4 antennas are selected in turn as the receiving antennas; the microprocessor 15 receives data from the in-phase analog-to-digital converter 30 and the orthogonal analog-to-digital converter 31, performs fast Fourier calculation on the data of the in-phase analog-to-digital converter 30 and the orthogonal analog-to-digital converter 31, and stores the fast Fourier calculation results of the output data of the in-phase analog-to-digital converter 14 and the orthogonal analog-to-digital converter 31.

[0061] In this embodiment, communication interface 16 utilizes an M905R-433 wireless transparent transmission module from Zhengzhou Yiling Electronic Technology Co., Ltd., with one module connected to each of the detection server and detection circuit microprocessors, forming a wireless communication interface. The power splitter is the ZN2PD2-63-S+MINI0.35-6.0 module from Shenzhen Baina (Shenzhen) Co., Ltd. The input of sinusoidal signal power splitter 17 is connected to RFOUTA, while the output is connected to the local oscillator input signal LOIN of the IQ demodulator and the mixer's RF_INA. Both the transmit and receive antenna interfaces are male BNC connectors, and the coaxial cables connected to them are female BNC connectors.

[0062] Circuit diagram of signal generator 13 Figure 10 , where US1: ADF4350, ANALOG DEVICES, USA; US2: 26 MHz active crystal oscillator; US3: ADF4153, ANALOG DEVICES, USA; CLKA, DATAA, LEA, CLKB, DATAB, LEB, MUXS, MUXO, and LD are connected to the IO pins of the microprocessor. RFOUTA is connected to the input of the sinusoidal signal power divider.

[0063] Circuit diagram of digital-to-analog converter 14 Figure 11 , where UDA1: AD5689, ANALOG DEVICES, USA; VOUTA is connected to the VOUTA of the mixer; SDO, RSTSEL, RESET, SDIN, SYNC, SCLK, LDAC are connected to the IO pins of the microprocessor; The circuit diagram of the in-phase mixer 22 is shown in FIG. Figure 12, wherein, UH1: ADL5350, ANALOG DEVICES, USA; S_OUT is connected to S_OUT of the transmitting power amplifier 24.

[0064] The circuit diagram of the transmitting power amplifier 24 is shown in FIG. Figure 13 UG1: HMC921, ANALOGDEVICES, USA; RFOUT is connected to the transmitting antenna.

[0065] Receiver low noise amplifier 25 circuit diagram reference Figure 14 Among them, ULP1: ADL5523, ANALOG DEVICES, USA; RX_IN: connected to the receiving antenna interface; RX_OUT is connected to the RX_OUT of the orthogonal demodulator.

[0066] Refer to 15 for the circuit diagram of the in-phase analog-to-digital converter 30 and the orthogonal analog-to-digital converter 31, wherein U5: AD9643, produced by ANALOG DEVICES, USA; VINA-, VINA+ are connected to the in-phase output VINA-, VINA+ of the IQ demodulator, VINB-, VINB+ are connected to the orthogonal output VINB-, VINB+ of the IQ demodulator, SCLK, SDO, CLK+, CLK-, D0+, D1+, ..., D13+, D0-, D1-, ..., D13-, are all connected to the IO interface of the microprocessor 15.

[0067] Matrix switch circuit diagram reference Figure 16 Among them, US1: ADG936, produced by ANALOG DEVICES of the United States; INA, INB are connected to the microprocessor; RFCA is connected to the transmitting antenna interface of the detection circuit; RFCB is connected to the receiving antenna interface of the detection circuit; RF1A is connected to the transmitting interface of the matrix switch A; RF1B is connected to the receiving interface of the matrix switch A; RF2A is connected to the transmitting interface of the matrix switch B; RF2B is connected to the receiving interface of the matrix switch B.

[0068] The circuit diagram of the quadrature demodulator 32 is shown in FIG. Figure 17 Among them, UD1: ADL5387, produced by ANALOGDEVICES of the United States.

[0069] Example 2 This embodiment is a further improvement based on the first embodiment. The specific improvement lies in proposing a method for obtaining the characteristic frequency. For other parts not mentioned, refer to the first embodiment or the prior art.

[0070] The method for obtaining the characteristic frequency is: SA, create multiple calibrated soil moisture distribution soil layers with different soil moisture; SB, through two symmetrically set antenna mounting poles, measure all the calibration soil moisture distribution soil layers in turn, and get and ; For the In the calibrated soil moisture distribution layer, the frequency of the detection circuit is , No. The dual antenna No. is the transmitting antenna and the The fast Fourier transform calculation result of the output data of the in-phase analog-to-digital converter 30 in the detection circuit is obtained when the dual antenna is the receiving antenna; For the In the calibrated soil moisture distribution layer, the frequency of the detection circuit is , No. The dual antenna No. is the transmitting antenna and the When the dual antenna is a receiving antenna, the fast Fourier transform calculation result of the output data of the orthogonal analog-to-digital converter 31 is obtained; SC, calculate the comprehensive fitting factor, the calculation method is:

[0071]

[0072] in, For the Calibrated soil moisture distribution layers and frequencies The comprehensive fitting factor between is the fitting factor; The sampling point of the 30-bit analog-to-digital converter is In the case of indivual The value of For middle The value of the variable constant The corresponding value when for middle The corresponding value when the value of is 1; The sampling point of the quadrature analog-to-digital converter 31 is In the case of indivual The value of for The value in is a variable constant The corresponding value when for middle The corresponding value when the value of is 1; The value range is ), B is the total number of soil layers with set calibration soil moisture content distribution; SD, in Within the value range, gradually calculate each Corresponding , and in the corresponding The maximum value is obtained from the B maximum values, and the B frequencies corresponding to the B maximum values ​​in the comprehensive fitting factors are used as B calibrated soil moisture distribution soil layer characteristic frequencies and numbered.

[0073] In this embodiment, the frequency set by the signal generator 13 is The range is 1 MHz to 100 MHz, and the frequency step is 1 MHz. Each measurement pulse is 100 complete sine waves. The sampling rate of the orthogonal analog-to-digital converter 31 and the in-phase analog-to-digital converter 30 is 20 times the frequency, and the number of sampling points is 2000, that is, .

[0074] For ease of understanding, ,in, 、 、 They are The specific values ​​of the 1st, 2nd and 2000th, = , , .

[0075] ,in, 、 、 They are The specific values ​​of the 1st, 2nd and 2000th, = , , .

[0076] Antenna combinations include: (TA1, TB1); (TA1, TB2); (TA1, TB3); (TA1, TB4); (TA2, TB1); (TA2, TB2); (TA2, TB3); (TA2, TB4); (TA3, TB1); (TA3, TB2); (TA3, TB3); (TA3, TB4); (TA4, TB1); (TA4, TB2); (TA4, TB3); (TA4, TB4), a total of 16 combinations; the combination method is used Mark, when , respectively, indicating that the transmitting antennas are TA1, TA2, TA3, and TA4. , representing the receiving antennas TB1, TB2, TB3, and TB4 respectively.

[0077] thereby middle, They are 1MHZ, 2 MHZ, 3MHZ, ..., 100MHZ, Take 1, 2, 3, ...B in sequence, and Take them in turn Specifically, take , find Coall( ,1), = the maximum value among 1, 2, 3…, 100, the maximum value is the corresponding characteristic frequency of the first calibrated soil moisture distribution layer; take , find out and The maximum value in , the frequency corresponding to the maximum value is the characteristic frequency of the corresponding calibrated soil moisture distribution soil layer, and the characteristic frequencies corresponding to B calibrated soil moisture distribution soil layers are found in this way.

[0078] Example 3 This embodiment is further limited on the basis of the embodiment 1. The specific improvement lies in proposing a method for producing a soil layer for calibrating the soil moisture distribution. For other parts not mentioned, refer to the embodiment 1 or the prior art.

[0079] This embodiment provides a method for calibrating soil moisture distribution layers, including the following steps: (1) Extract soil samples from the test points of the monitoring soil layer; (2) Dry the soil sample and grind it with a grinder; (3) Take dried soil and water and mix them with a mixer; (4) Place soil samples in multiple test chambers according to the uniform humidity and stratified humidity methods, and install humidity sensors. Use the humidity sensors to calibrate the soil moisture distribution of the two soil layers, uniform humidity and stratified humidity.

[0080] The test chamber measures 1 meter in length, width, and height. Uniform humidity means all soil has the same humidity. Stratified humidity means the humidity increases in layers from bottom to top.

[0081] In this embodiment, ten types of calibrated soil moisture distribution soil layers with uniform humidity of 5%, 10%, 15%, ..., and 50% were prepared respectively; a total of seven types of calibrated soil moisture distribution soil layers with stratified humidity were prepared, all of which were set in 20 cm thick layers. The stratified humidity is shown in Table 1: Table 1 Layered humidity of soil layers for seven calibrated soil moisture distributions

[0082] Therefore, this embodiment has a total of 17 calibrated soil moisture distribution layers, namely , .

[0083] In summary, the beneficial effects of this solution are: The present invention is to install two antennas on the poles The dual antenna creates an antenna array by This combination method realizes the acquisition of soil information from different angles and depths, and realizes multi-path measurement. Multi-path measurement makes it easier to determine the calibration soil moisture distribution layer that is closest to the monitored soil layer. The calibration soil moisture distribution layer is the benchmark value set for the calibration experiment. Taking into account the complex and changeable conditions of the actual monitored soil layer, the calibration experimental soil layer has stronger robustness. Even when the environmental conditions change, the strategy can be quickly adjusted by comparing the calibration data to ensure the continuity and stability of the monitoring work, which is convenient for experts to assess the accurate geological disaster warning level.

[0084] Although the specific embodiments of the invention are described in detail in conjunction with the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Within the scope described by the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A soil moisture testing method based on transmission parameters, characterized in that: Includes steps: S1, set both The antenna mounting poles of the dual antennas are symmetrically fixed in the monitoring soil and The dual antennas are electrically connected to the detection circuit through a matrix switch. is a natural number greater than or equal to 3; S2, through the detection circuit The dual antennas are sorted and numbered, and divided into groups of two by two. A group of measuring antennas, and the two dual antennas of each group of measuring antennas are used as the transmitting antenna and the receiving antenna of the detection circuit respectively; S3, the signal frequency of the signal generator in the detection circuit is set to a plurality of different characteristic frequencies in sequence to obtain the measurement data of the monitored soil layer, the measurement data includes and ,in For the At the characteristic frequency, The dual antenna No. is the transmitting antenna and the The fast Fourier calculation result of the output data of the in-phase analog-to-digital converter in the detection circuit is obtained when the dual antenna is the receiving antenna; In the At the characteristic frequency, The dual antenna No. is the transmitting antenna and the The fast Fourier calculation result of the output data of the orthogonal analog-to-digital converter in the detection circuit is obtained when the dual antenna is the receiving antenna; S4. Calculate the comparison fitting factor between the measured data and the calibration data ; Calibration data includes and , For the In the calibrated soil moisture distribution soil layer, At the characteristic frequency, The dual antenna No. is the transmitting antenna and the The fast Fourier calculation result of the output data of the in-phase analog-to-digital converter obtained when the dual antenna is the receiving antenna; For the Calibrated soil moisture distribution in soil layers, At the characteristic frequency, The dual antenna No. is the transmitting antenna and the The fast Fourier calculation result of the orthogonal analog-to-digital converter output data obtained when the dual antenna is the receiving antenna; For the Calibrate the soil moisture distribution layer, At the characteristic frequency, The dual antenna No. is the transmitting antenna and the When the dual antenna is the receiving antenna, and Comparison fitting factor with calibration data; S5. According to The maximum value of the comprehensive correlation factor between the measured data and the calibration data is calculated, and the calibrated soil moisture distribution layer corresponding to the maximum value of the comprehensive correlation factor is used as the actual soil moisture distribution layer of the monitoring soil layer; S6. Based on the actual soil moisture content, soil layer distribution and geological structure of the monitored soil layer, the geological disaster warning level of the monitored soil layer is given by expert evaluation.

2. The soil moisture content testing method according to claim 1, characterized in that: The antenna mounting column comprises a shell which is hollow inside and open at the top, the front projection of the shell is an inverted triangle, and both side surfaces of the shell are arc surfaces, a plurality of antenna holes are symmetrically opened on the arc surface walls on both sides of the shell along the central axis of the shell, the interior of the shell is filled with an antenna insulation layer, a plurality of antennas are symmetrically arranged in the antenna insulation layer, the bottom ends of the plurality of antennas respectively pass through the plurality of antenna holes on the arc surface walls on both sides and contact with the monitored soil, and the top ends of the plurality of antennas are electrically connected to the detection circuit; The two antennas located at the same height on the two side arc walls form a dual antenna.

3. The soil moisture content testing method according to claim 2, characterized in that: The multiple antenna holes on the curved walls on both sides are evenly spaced and distributed along the height direction of the shell.

4. The soil moisture content testing method according to claim 2, characterized in that: A plurality of lead-in holes for guiding and fixing the antenna are arranged inside the antenna insulation layer. The plurality of lead-in holes correspond to the plurality of antenna holes in a one-to-one relationship. The bottom end of each lead-in hole is bent and connected to the corresponding antenna hole, and the diameter of each lead-in hole is smaller than the diameter of the corresponding antenna hole.

5. The soil moisture content testing method according to claim 1, characterized in that: Each antenna mounting post The dual antennas are electrically connected to the detection circuit through a matrix switch.

6. The soil moisture content testing method according to claim 1, characterized in that: The detection circuit includes a microprocessor provided with a communication interface, the microprocessor is sequentially connected to a signal generator, a sinusoidal signal power divider, a transmission mixer, a transmission power amplifier and a transmission antenna interface connected to a matrix switch, wherein the transmission mixer is connected to the microprocessor via a digital-to-analog converter; The sinusoidal signal power divider is also connected to the orthogonal demodulator, the orthogonal demodulator is respectively connected to the in-phase analog-to-digital converter, the orthogonal analog-to-digital converter and the receiving antenna interface, and the in-phase analog-to-digital converter and the orthogonal analog-to-digital converter are both connected to the microprocessor.

7. The soil moisture content testing method according to claim 6, characterized in that: The orthogonal demodulator includes a coupler connected to the sinusoidal signal power divider, one output end of the coupler is connected to the in-phase mixer, the in-phase low noise amplifier and the in-phase analog-to-digital converter in sequence, and the other output end of the coupler is connected to the orthogonal mixer, the orthogonal low noise amplifier and the orthogonal analog-to-digital converter in sequence; wherein, the in-phase mixer and the orthogonal mixer are both connected to the receiving power divider, and the receiving power divider is connected to the receiving antenna interface through the receiving low noise amplifier. The microprocessor is connected to the remote monitoring terminal signal for sending detection instructions and receiving data through the communication interface.

8. The soil moisture content testing method according to claim 1, characterized in that: The method for obtaining the characteristic frequency is: SA, making multiple calibrated soil moisture distribution soil layers with different soil moisture; SB, through two symmetrically set antenna mounting poles to measure all the calibration soil moisture distribution soil layers in turn, get and ; For the In the calibrated soil moisture distribution layer, the frequency of the detection circuit is , No. The dual antenna No. is the transmitting antenna and the The fast Fourier calculation result of the output data of the in-phase analog-to-digital converter in the detection circuit is obtained when the dual antenna is the receiving antenna; For the In the calibrated soil moisture distribution layer, the frequency of the detection circuit is , No. The dual antenna No. is the transmitting antenna and the When the dual antenna is the receiving antenna, the fast Fourier calculation result of the orthogonal analog-to-digital converter output data is obtained; SC, calculate the comprehensive fitting factor, the calculation method is: in, For the Calibrated soil moisture distribution soil layer and frequency The comprehensive fitting factor between is the fitting factor; The sampling point of the in-phase analog-to-digital converter is In the case of indivual The value of For middle The value of the variable constant The corresponding value when for middle The corresponding value when the value of is 1; The sampling point of the quadrature analog-to-digital converter is In the case of indivual The value of for The value in is a variable constant The corresponding value when for middle The corresponding value when the value of is 1; The value range is ), B is the total number of soil layers with set calibration soil moisture content distribution; SD, in Within the value range, gradually calculate each Corresponding , and in the corresponding The maximum value is obtained, and the comprehensive fitting factors of B maximum values ​​are obtained. The B frequencies corresponding to the comprehensive fitting factors of the B maximum values ​​are respectively used as B calibrated soil moisture content distribution soil layer characteristic frequencies.

9. The soil moisture content testing method according to claim 8, characterized in that: Comparative Fit Factor The calculation method is: in, The sampling point of the in-phase analog-to-digital converter is In the case of indivual The value of For middle The value of The value at the characteristic frequency; The sampling point of the quadrature analog-to-digital converter is In the case of indivual The value of for middle The value of The value at the characteristic frequency.

10. The soil moisture content testing method according to claim 9, characterized in that: The calculation method of the comprehensive correlation factor is: in, For the A comprehensive correlation factor between the calibrated soil moisture distribution layer and the measured data; For the The soil layer factor of the calibrated soil moisture distribution layer is the same as the measured data; For the Calibrate soil moisture content distribution soil layer and different soil layer factors of measurement data; The value range is ), B is the total number of soil layers for the calibration soil moisture distribution.

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