Method and device for measuring soil moisture

Abstract

The invention discloses a method and a device for measuring soil moisture. The method comprises the steps that variable-frequency electromagnetic wave signals with the frequency ranging from # imgabs0 # to # imgabs1 # are transmitted to a probe placed in soil, corresponding variable-frequency reflection signals are received and obtained, the variable-frequency reflection signals are subjected to complex radical treatment to obtain complex radical reflection signals, # imgabs2 # is the minimum value of the frequency, and # imgabs3 # is the maximum value of the frequency; inverse Fourier transform is carried out on the complex-base reflection signal to obtain a reflection coefficient formula; obtaining a reflection time interval according to a reflection coefficient formula, wherein the reflection time interval is the travel time of the electromagnetic wave signal propagating along the probe obtained according to the time points of two reflections generated at the starting position and the ending position of the probe inserted into the soil; the apparent dielectric constant of the soil is obtained according to the reflection time interval, and the soil volume moisture content is calculated. According to the method, the application bottleneck problem that the moisture monitoring equipment is influenced by soil types, cultivation, climate and the like and needs to be subjected to fixed-point and frequent formula calibration is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil moisture measurement, and in particular to a method and device for measuring soil moisture. Background Art

[0002] Time Domain Reflectometry (TDR) is an electronic measurement technology developed in the 1930s: electromagnetic waves are transmitted along transmission lines, and changes in impedance on the transmission lines will cause electromagnetic wave signals to be reflected. The location of the impedance discontinuity point is determined by measuring the transmission time of the electromagnetic waves. Time Domain Reflectometry was first used in soil moisture measurement in the 1960s and was basically mature in the 1980s.

[0003] Other dielectric methods for measuring soil moisture are greatly affected by the changes in the conductivity of the measured soil due to the electromagnetic parameters or technical methods based on which the measurement is based. Factors such as soil type, salinity, application amount of inorganic fertilizers and organic fertilizers, conductivity of soil water content, soil density and soil crystal structure will affect soil conductivity. Therefore, it is often necessary to calibrate the formula used based on the actual measurement (monitoring) of the original soil, so the actual application effect is limited to a certain extent. Time domain carrierless pulse system TDR is generally considered by the industry to be the most effective and reliable method for measuring soil moisture. However, it also has the following weaknesses: 1) The high-speed delay line technology on which this technology relies is expensive, which has limited its large-scale use for more than 40 years; 2) Due to the extremely complex composition and structure of the soil, its measurement trace is also relatively complex, and it often requires professional training to identify the correct reflection position on the image, and the precise reflection time point needs to be determined by using the double tangent algorithm on its measurement trace image, which also reduces the measurement reliability of automatic online monitoring.

[0004] Although the technology of measuring soil moisture by time-domain carrier-free pulse system TDR has been mature for more than 40 years, it has not been widely promoted and applied due to the problem of application cost. Other technologies, such as frequency domain method and standing wave method, although their cost price is lower, all measure soil moisture by measuring the effective dielectric constant of soil, and the effective dielectric constant of soil is greatly affected by the conductivity of soil. The type of soil and tillage will cause the conductivity of soil to change. Therefore, this type of equipment needs to be calibrated according to the measured soil. This calibration needs to be carried out regularly in the field, which is almost impossible to achieve in actual operation.

[0005] Over the years, people have been looking for other electromagnetic wave transmission time measurement mechanisms for measuring soil moisture in the time domain to reduce the application cost of TDR technology. However, the common problem with this type of instrument is that the method they use to measure the electromagnetic wave transmission time is greatly affected by conductivity, and therefore still relies on formula calibration.

[0006] Currently, no effective solution has been proposed for the above-mentioned problems existing in the related technologies. Summary of the invention

[0007] The main purpose of the present application is to provide a method and device for measuring soil moisture, so as to at least solve the problem in the related art that soil moisture measurement is greatly affected by conductivity changes.

[0008] In order to achieve the above-mentioned object, according to one aspect of the present application, a method for measuring soil moisture is provided. The method comprises: transmitting a frequency of arrive The frequency-converted electromagnetic wave signal is received to obtain a corresponding frequency-converted reflected signal, and the frequency-converted reflected signal is complexed to obtain a complex-based reflected signal, wherein: is the minimum value of frequency, is the maximum value of the frequency; perform inverse Fourier transform on the complex reflected signal to obtain the reflection coefficient formula, where the reflection coefficient formula is an analytical expression of the reflection coefficient with respect to time; obtain the reflection time interval based on the reflection coefficient formula, and the reflection time interval is the travel time of the electromagnetic wave signal along the probe obtained based on the time points of two reflections generated at the starting point and the end point when the probe is inserted into the soil; obtain the apparent dielectric constant of the soil based on the reflection time interval, and calculate the soil volume moisture content.

[0009] Optionally, an electromagnetic wave signal is obtained, and the electromagnetic wave signal is expressed as:

[0010] ,in, is the frequency, is the voltage amplitude, For frequency and time The transmitted signal is obtained; the reflected signal generated after the reflection time is obtained, and the reflected signal is expressed as:

[0011] ,in, is the reflection time, For frequency and reflection time The reflected signal, is the reflection coefficient.

[0012] Optionally, the reflected signal is complexed to obtain a complexed reflected signal, and the complexed reflected signal is:

[0013] ,in, is the reflection coefficient.

[0014] Optionally, a time domain reflection signal is obtained according to the complex basis reflection signal, and the calculation formula is: ,in, is the time domain reflection signal, is the complexation reflection signal, Inverse Fourier transform operator symbol.

[0015] Optionally, the time domain reflection signal is calculated to obtain:

[0016] ,

[0017] in, , , is the bandwidth, is the center frequency, is the sine function:

[0018] .

[0019] Optionally, the modulus of the time domain reflection signal is obtained. The modulus of the time domain reflection signal is:

[0020] ,

[0021] make , then we get the reflection coefficient with respect to time The analytical expression of is:

[0022] .

[0023] Optionally, calculate the apparent dielectric constant using the formula ,in, is the apparent dielectric constant, is the speed of light, is the probe length, is the reflection time interval; the soil volume moisture content is calculated using the first calculation formula or the second calculation formula, wherein the first calculation formula is: , the second calculation formula is: , is the volumetric moisture content of soil.

[0024] According to another aspect of the present application, a device for measuring soil moisture is provided. The device comprises: a transmitting unit for transmitting a frequency of arrive The frequency-converted electromagnetic wave signal is received to obtain a corresponding frequency-converted reflected signal, and the frequency-converted reflected signal is complexed to obtain a complex-based reflected signal, wherein: is the minimum value of frequency, is the maximum value of the frequency; a transformation unit performs inverse Fourier transform on the complex basis reflection signal to obtain a reflection coefficient formula, wherein the reflection coefficient formula is an analytical expression of the reflection coefficient relative to time; an acquisition unit obtains a reflection time interval according to the reflection coefficient formula, wherein the reflection time interval is the travel time of the electromagnetic wave signal along the probe obtained based on the time points of two reflections generated at the starting point and the end point when the probe is inserted into the soil; a calculation unit obtains the apparent dielectric constant of the soil according to the reflection time interval, and calculates the soil volume moisture content.

[0025] In order to achieve the above objective, according to another aspect of the present application, a computer-readable storage medium is provided, the computer-readable storage medium comprising a stored program, wherein the program executes any one of the above methods for measuring soil moisture.

[0026] According to another aspect of the present application, an electronic device is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include a method for measuring soil moisture for executing any one of the items.

[0027] Through the present application, the following steps are adopted: transmitting an electromagnetic wave signal, receiving at least two reflected signals, and complexing the reflected signal to obtain a complex reflected signal; performing an inverse Fourier transform on the complex reflected signal to obtain a reflection coefficient formula; obtaining a reflection time interval according to the reflection coefficient formula, wherein the reflection time interval is the interval time for receiving two adjacent reflected signals; and calculating the soil volume moisture content according to the reflection time interval, thereby solving the application bottleneck problem in the related art that moisture monitoring equipment is affected by soil type, tillage, climate, etc., and needs to be calibrated at a fixed point and regularly. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 is a flow chart of a method for measuring soil moisture provided according to an embodiment of the present application;

[0030] Figure 2 It is a schematic diagram of the reflection of electromagnetic signals;

[0031] Figure 3 is the electromagnetic polarization dielectric spectrum of water;

[0032] Figure 4 Trace diagram for measuring coaxial cable;

[0033] Figure 5 This is a schematic diagram of the SFCW-TDR device system for measuring soil;

[0034] Figure 6 is the actual measurement trace diagram;

[0035] Figure 7 Schematic diagram of the TDR system for measuring soil moisture;

[0036] Figure 8 It is the measurement curve diagram of Topp formula and Ferry formula;

[0037] Fig. 9 It is a structural block diagram of a device for measuring soil moisture provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0038] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0040] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0041] For the convenience of description, some nouns or terms involved in the embodiments of the present application are explained below:

[0042] Complexification: Under real numbers, it is a cosine function, but in electromagnetism, everything is based on complex numbers, so it must be converted into the complex form of e.

[0043] As introduced in the background technology, soil moisture measurement in the prior art is affected by soil conductivity and needs to be calibrated through a formula. In order to solve the problem that soil moisture measurement in the related technology is greatly affected by conductivity changes, the embodiments of the present application provide a method and device for measuring soil moisture.

[0044] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0045] In this embodiment, a method for measuring soil moisture running on a mobile terminal, a computer terminal or a similar computing device is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0046] Figure 1 FIG. 1 is a flow chart of a method for measuring soil moisture according to an embodiment of the present application. Figure 1 As shown, the method comprises the following steps:

[0047] Step S101, transmitting a frequency of arrive The frequency-converted electromagnetic wave signal is received to obtain a corresponding frequency-converted reflected signal, and the frequency-converted reflected signal is complexed to obtain a complex-based reflected signal, wherein: is the minimum value of frequency, is the maximum value of frequency;

[0048] like Figure 2 As shown, Figure 2 This is a schematic diagram of the reflection of electromagnetic signals. Electromagnetic waves are transmitted along the transmission line at a constant rate. Assume that the time along the transmission line is The reflection coefficient at a point is the ratio of the input voltage to the reflected voltage. In electromagnetic wave theory, it is expressed as a complex number , is the modulus, which represents the change in its amplitude voltage, and It represents the change of phase, which can be regarded as a time A function of frequency. , electromagnetic wave signal with amplitude A: ; Over time The reflected signal generated, after time Back to the transmitting point, the signal is transmitted back to the receiver, and the receiver gets a frequency signal. With time Function (reflection signal): .

[0049] Step S102, performing inverse Fourier transform on the complex basis reflection signal to obtain a reflection coefficient formula, wherein the reflection coefficient formula is an analytical expression of the reflection coefficient relative to time;

[0050] Specifically, the operation on the complex reflection signal is to convert it from a frequency domain signal into a time domain signal. Since the operation from the frequency domain signal is easily affected by the conductivity, it is converted into a time domain signal, and the reflection time interval is derived from the time domain signal to measure the soil moisture.

[0051] Step S103, obtaining a reflection time interval according to a reflection coefficient formula, where the reflection time interval is the travel time of the electromagnetic wave signal propagating along the probe obtained based on the time points of two reflections generated at the start and end points of the probe being inserted into the soil;

[0052] Specifically, through the formula By calculation, the reflection time interval can be obtained.

[0053] Step S104, obtaining the apparent dielectric constant of the soil according to the reflection time interval, and calculating the volumetric moisture content of the soil.

[0054] Specifically, under the action of electromagnetic fields within a certain frequency range, the real part of the relative dielectric constant of water is relatively stable. In electromagnetic theory, dimensionless complex numbers are usually used: , in fact Describes its ability to store and polarize electromagnetic energy. Electromagnetic fields of different frequencies will stimulate polarization of different properties of the medium, resulting in different decays of the real part of the dielectric constant of the material, which are called Decay (spatial polarization), Decay (turn to polarization), Decay (ion polarization) and decay (electronic polarization), thus is a function of frequency. Figure 3 It can be seen that when the frequency of the applied electromagnetic wave is in the range of about 1 MHz to 2 GHz, the water molecules are between spatial polarization and steering polarization, and the real part of their dielectric constant is relatively stable. Therefore, the time domain reflectometry method for measuring soil moisture mostly uses electromagnetic signals in this frequency band.

[0055] Soil is a three-phase mixture consisting of air (gas phase), mineral particles (solid phase) and water (liquid phase). The real part of the relative dielectric constant of air is 1, that of mineral particles is between 2 and 4, and the real part of the relative dielectric constant of water at 20°C is as high as 81.2. As the temperature drops, the value increases slightly, and vice versa, but it varies between 75 and 88, which is much higher than other phases. Therefore, the real part of the relative dielectric constant of soil mainly depends on the soil moisture content. The apparent dielectric constant is calculated by the reflection event interval. Since the apparent dielectric constant of soil is close to the real part of its relative dielectric constant under the action of electromagnetic waves of sufficiently high frequency, the soil volume moisture content is calculated by the apparent dielectric constant.

[0056] Since soil type, tillage, etc. will cause changes in soil conductivity, this type of equipment needs to be calibrated according to the measured soil formula. Through this embodiment, the influence of soil conductivity on the measurement result can be reduced when measuring the soil volume moisture content. The present invention provides a reliable and relatively low-cost electromagnetic wave transmission time measurement method, which is less affected by conductivity changes and can achieve moisture measurement of most agricultural cultivated soils without formula calibration.

[0057] In an optional embodiment, an electromagnetic wave signal is acquired, and the electromagnetic wave signal is expressed as:

[0058] ,in, is the frequency, is the voltage amplitude, For frequency and time The transmitted signal is obtained; the reflected signal generated after the reflection time is obtained, and the reflected signal is expressed as:

[0059] ,in, is the reflection time, For frequency and reflection time The reflected signal, is the reflection coefficient.

[0060] like Figure 4 , Figure 4 To measure the trace diagram of the coaxial cable, a trace is generated by a 2-meter coaxial cable with an impedance of 25Ω, where It is the reflection generated by the 50 ohm impedance system connected to the 25 ohm cable. is the reflection at the end of the cable. It is the second reflection. It is the third reflection.

[0061] like Figure 5 as well as Figure 6, Figure 5 This is a schematic diagram of the SFCW-TDR soil measurement system. Figure 6 This is the actual measurement trace diagram, where the horizontal axis is the time domain, indicating the travel time of the electromagnetic wave, and the vertical axis indicates the reflection coefficient of each point along the electromagnetic wave. When a measurement starts, the SFCW-TDR signal generator transmits the step-by-step high-frequency signal in sequence, and the reflected signal is separated by the signal coupler to obtain the sampling signal, which is transmitted to the signal processing system to form Figure 6 The electromagnetic wave travels along the transmission line. When it enters the bottom of the probe inserted into the soil, the impedance change forms the first strong reflection m1. The signal that continues to transmit reaches the top of the probe and forms the second strong reflection m2. The time interval between the two reflections is thus measured. , the apparent dielectric constant of the measured soil is calculated, and then the volumetric moisture content of the soil is obtained.

[0062] It can be seen that it reflects the process of time domain reflection more clearly, which is completely different from the waveform collected by the analog carrier-free pulse system. It has a high degree of digitization and is more likely to meet the requirements of online automatic monitoring.

[0063] In an optional embodiment, the reflection signal is complexed to obtain a complex reflection signal, and the complex reflection signal is:

[0064] ,in, is the reflection coefficient.

[0065] Specifically, the complex basis of the reflected signal is to convert the real number into a cosine function, but electromagnetism is based on complex numbers, so it must be converted into a complex form, which is called complex basis.

[0066] In an optional embodiment, a time domain reflection signal is obtained according to the complex basis reflection signal, and the calculation formula is: ,in, is the time domain reflection signal, is the complexation reflection signal, Inverse Fourier transform operator symbol.

[0067] Specifically,

[0068]

[0069]

[0070]

[0071] , after calculation, the expression of the time domain reflection signal is obtained.

[0072] In an optional embodiment, the time domain reflection signal is calculated to obtain:

[0073] ,

[0074] in, , , is the bandwidth, is the center frequency, is the sine function:

[0075] .

[0076] Get the modulus of the time domain reflection signal. The modulus of the time domain reflection signal is:

[0077] ,

[0078] make , then we get the reflection coefficient relative to time The analytical expression of is:

[0079] .

[0080] Specifically, in the above calculation process, a diagonal mathematical calculation method is used, so Became Therefore, this scheme can obtain the reflection coefficient with respect to time by discrete sampling according to the step frequency and fast inverse Fourier transform (IFFT). Waveform expression.

[0081] In an optional embodiment, the apparent dielectric constant is calculated using the formula: ,in, is the apparent dielectric constant, is the speed of light, is the probe length, is the reflection time interval; the soil volume moisture content is calculated using the first calculation formula or the second calculation formula, wherein the first calculation formula is: , the second calculation formula is: , is the volumetric moisture content of soil.

[0082] Under the action of electromagnetic waves of sufficiently high frequency, the apparent dielectric constant of the soil is approximately equal to the real part of its relative dielectric constant, and the transmission speed of electromagnetic waves in the medium is The relationship that satisfies the following formula: ,in, is the speed of light, is the real part of the dielectric constant of the medium, and , is called the loss factor, where is the frequency of the electromagnetic wave, is the DC conductivity of the medium, is the imaginary part of the relative permittivity of the medium, Siemens / meter is the absolute dielectric constant of vacuum.

[0083] Soil is basically a unidirectional linear homogeneous medium, which satisfies: , when the applied electromagnetic wave frequency is high enough Established, so: , Defined as the apparent dielectric constant of a medium.

[0084] A TDR system for measuring soil moisture is as follows: Figure 7 As shown in the figure, when an electromagnetic signal reaches the starting part of the probe at time t0 along the coaxial cable, reflection occurs due to the change in impedance, and the remaining signal continues to move along the probe and reaches the bottom of the probe at time t1, and a second reflection occurs. Considering the travel of the electromagnetic wave along the probe with a length of L, it is easy to see that: , will be based on the above get: .

[0085] It can be seen that by measuring the transmission time ∆t of the electromagnetic wave along the probe, the dielectric constant of the medium can be directly obtained. Through the above analysis, it can be known that by measuring the real part of the relative dielectric constant of the soil, the volumetric moisture content of the soil can be determined.

[0086] The two formulas for calculating soil volume moisture content are: Topp formula: , Ferre formula: , is the volumetric water content of soil, is the apparent dielectric constant. Figure 8 As shown, Figure 8 is the measurement curve of Topp formula and Ferry formula, Figure 8 These two formulas reflect the change of soil volume moisture content with apparent dielectric constant between 3 and 27. It is easy to see that the two formulas are highly consistent within this range. In particular, the TOPP formula describing the relationship between soil volume moisture content and apparent dielectric constant is obtained by linear regression fitting. A large number of experimental results at home and abroad show that soil density or porosity has a certain influence on the dielectric constant of moist soil, but when the soil bulk density is between 1.00 and 1.7 𝑔 / cm -1 This formula has better adaptability when the range changes.

[0087] The present application embodiment also provides a device for measuring soil moisture. It should be noted that a device for measuring soil moisture in the present application embodiment can be used to perform a method for measuring soil moisture provided in the present application embodiment. The device is used to implement the above-mentioned embodiments and preferred implementations, and those that have been described are not repeated here. As used below, the term "module" can implement a combination of software and / or hardware of a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware is also possible and conceived.

[0088] The following is an introduction to a device for measuring soil moisture provided in an embodiment of the present application.

[0089] Fig. 9 is a structural block diagram of a device for measuring soil moisture according to an embodiment of the present application. Fig. 9 As shown, the device comprises: a transmitting unit 901, which is used to transmit a frequency of arrive The frequency-converted electromagnetic wave signal is received to obtain a corresponding frequency-converted reflected signal, and the frequency-converted reflected signal is complexed to obtain a complex-based reflected signal, wherein: is the minimum value of frequency, is the maximum value of the frequency; a transformation unit 902 is used to perform an inverse Fourier transform on the complex basis reflection signal to obtain a reflection coefficient formula, wherein the reflection coefficient formula is an analytical expression of the reflection coefficient with respect to time; an acquisition unit 903 is used to obtain a reflection time interval according to the reflection coefficient formula, wherein the reflection time interval is the travel time of the electromagnetic wave signal along the probe obtained according to the time points of two reflections generated at the starting point and the end point when the probe is inserted into the soil; a calculation unit 904 is used to obtain the apparent dielectric constant of the soil according to the reflection time interval, and calculate the soil volume moisture content.

[0090] In an optional embodiment, the transmitting unit 901 includes: a first acquisition subunit, configured to acquire an electromagnetic wave signal, where the electromagnetic wave signal is represented as:

[0091] ,in, is the frequency, is the voltage amplitude, For frequency and time The second acquisition subunit is used to obtain the reflection signal generated after the reflection time, and the reflection signal is expressed as:

[0092] ,in, is the reflection time, For frequency and reflection time The reflected signal, is the reflection coefficient.

[0093] In an optional embodiment, the transmitting unit 901 includes: a conversion subunit, which is used to complex the reflection signal to obtain a complex reflection signal, and the complex reflection signal is:

[0094] ,in, is the reflection coefficient.

[0095] In an optional embodiment, the transform unit 902 includes: a third acquisition subunit, configured to acquire a time domain reflection signal according to the complex basis reflection signal, and the calculation formula is: ,in, is the time domain reflection signal, is the complexation reflection signal, Inverse Fourier transform operator symbol.

[0096] In an optional embodiment, the transform unit 902 includes: a first calculation subunit, configured to calculate the time domain reflection signal to obtain:

[0097] ,

[0098] in, , , is the bandwidth, is the center frequency, is the sine function:

[0099] .

[0100] In an optional embodiment, the transform unit 902 includes: a fourth acquisition subunit, configured to acquire a modulus of the time domain reflection signal, where the modulus of the time domain reflection signal is:

[0101] ,

[0102] make , then we get the reflection coefficient relative to time The analytical expression of is:

[0103] .

[0104] In an optional embodiment, the calculation unit 904 includes: a second calculation subunit, which is used to calculate the apparent dielectric constant, and the calculation formula is: ,in, is the apparent dielectric constant, is the speed of light, is the probe length, is the reflection time interval; the soil volume moisture content is calculated using the first calculation formula or the second calculation formula, wherein the first calculation formula is: , the second calculation formula is: , is the volumetric moisture content of soil.

[0105] The device for measuring soil moisture includes a processor and a memory, the transmitting unit 901 and the like are stored in the memory as program units, and the processor executes the program units stored in the memory to implement corresponding functions. The modules are all located in the same processor; or, the modules are located in different processors in any combination.

[0106] The processor includes a kernel, which retrieves the corresponding program unit from the memory. One or more kernels can be set, and the technical problem that soil moisture measurement is greatly affected by conductivity changes can be solved by adjusting kernel parameters.

[0107] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0108] An embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the method for measuring soil moisture.

[0109] Specifically, a method for measuring soil moisture includes: transmitting a frequency of arrive The frequency-converted electromagnetic wave signal is received to obtain a corresponding frequency-converted reflected signal, and the frequency-converted reflected signal is complexed to obtain a complex-based reflected signal, wherein: is the minimum value of frequency, is the maximum value of the frequency; perform inverse Fourier transform on the complex reflected signal to obtain the reflection coefficient formula, where the reflection coefficient formula is an analytical expression of the reflection coefficient with respect to time; obtain the reflection time interval based on the reflection coefficient formula, and the reflection time interval is the travel time of the electromagnetic wave signal along the probe obtained based on the time points of two reflections generated at the starting point and the end point when the probe is inserted into the soil; obtain the apparent dielectric constant of the soil based on the reflection time interval, and calculate the soil volume moisture content.

[0110] Optionally, an electromagnetic wave signal is obtained, and the electromagnetic wave signal is expressed as:

[0111] ,in, is the frequency, is the voltage amplitude, For frequency and time The transmitted signal is obtained; the reflected signal generated after the reflection time is obtained, and the reflected signal is expressed as:

[0112] ,in, is the reflection time, For frequency and reflection time The reflected signal, is the reflection coefficient.

[0113] Optionally, the reflected signal is complexed to obtain a complexed reflected signal, and the complexed reflected signal is:

[0114] ,in, is the reflection coefficient.

[0115] Optionally, a time domain reflection signal is obtained according to the complex basis reflection signal, and the calculation formula is: ,in, is the time domain reflection signal, is the complexation reflection signal, Inverse Fourier transform operator symbol.

[0116] Optionally, the time domain reflection signal is calculated to obtain:

[0117] ,

[0118] in, , , is the bandwidth, is the center frequency, is the sine function:

[0119] .

[0120] Optionally, the modulus of the time domain reflection signal is obtained. The modulus of the time domain reflection signal is:

[0121] ,

[0122] make , then we get the reflection coefficient relative to time The analytical expression of is:

[0123] .

[0124] Optionally, calculate the apparent dielectric constant using the formula ,in, is the apparent dielectric constant, is the speed of light, is the probe length, is the reflection time interval; the soil volume moisture content is calculated using the first calculation formula or the second calculation formula, wherein the first calculation formula is: , the second calculation formula is: , is the volumetric moisture content of soil.

[0125] An embodiment of the present invention provides a processor, which is used to run a program, wherein the method for measuring soil moisture is executed when the program is run.

[0126] Specifically, a method for measuring soil moisture includes: transmitting a frequency of arrive The frequency-converted electromagnetic wave signal is received to obtain a corresponding frequency-converted reflected signal, and the frequency-converted reflected signal is complexed to obtain a complex-based reflected signal, wherein: is the minimum value of frequency, is the maximum value of the frequency; perform inverse Fourier transform on the complex reflected signal to obtain the reflection coefficient formula, where the reflection coefficient formula is an analytical expression of the reflection coefficient with respect to time; obtain the reflection time interval based on the reflection coefficient formula, and the reflection time interval is the travel time of the electromagnetic wave signal along the probe obtained based on the time points of two reflections generated at the starting point and the end point when the probe is inserted into the soil; obtain the apparent dielectric constant of the soil based on the reflection time interval, and calculate the soil volume moisture content.

[0127] Optionally, an electromagnetic wave signal is obtained, and the electromagnetic wave signal is expressed as:

[0128] ,in, is the frequency, is the voltage amplitude, For frequency and time The transmitted signal is obtained; the reflected signal generated after the reflection time is obtained, and the reflected signal is expressed as:

[0129] ,in, is the reflection time, For frequency and reflection time The reflected signal, is the reflection coefficient.

[0130] Optionally, the reflected signal is complexed to obtain a complexed reflected signal, and the complexed reflected signal is:

[0131] ,in, is the reflection coefficient.

[0132] Optionally, a time domain reflection signal is obtained according to the complex basis reflection signal, and the calculation formula is: ,in, is the time domain reflection signal, is the complexation reflection signal, Inverse Fourier transform operator symbol.

[0133] Optionally, the time domain reflection signal is calculated to obtain:

[0134] ,

[0135] in, , , is the bandwidth, is the center frequency, is the sine function:

[0136] .

[0137] Optionally, the modulus of the time domain reflection signal is obtained. The modulus of the time domain reflection signal is:

[0138] ,

[0139] make , then we get the reflection coefficient relative to time The analytical expression of is:

[0140] .

[0141] Optionally, calculate the apparent dielectric constant using the formula ,in, is the apparent dielectric constant, is the speed of light, is the probe length, is the reflection time interval; the soil volume moisture content is calculated using the first calculation formula or the second calculation formula, wherein the first calculation formula is: , the second calculation formula is: , is the volumetric moisture content of soil.

[0142] An embodiment of the present invention provides a device, comprising a processor, a memory, and a program stored in the memory and executable on the processor, wherein when the processor executes the program, at least the following steps are implemented: transmitting a signal having a frequency of arrive The frequency-converted electromagnetic wave signal is received to obtain a corresponding frequency-converted reflected signal, and the frequency-converted reflected signal is complexed to obtain a complex-based reflected signal, wherein: is the minimum value of frequency, is the maximum value of the frequency; perform inverse Fourier transform on the complex basis reflection signal to obtain the reflection coefficient formula, where the reflection coefficient formula is an analytical expression of the reflection coefficient relative to time; obtain the reflection time interval based on the reflection coefficient formula, and the reflection time interval is the travel time of the electromagnetic wave signal along the probe based on the time points of the two reflections generated at the start and end of the probe inserted into the soil; obtain the apparent dielectric constant of the soil based on the reflection time interval, and calculate the soil volume moisture content. The device in this article can be a server, PC, PAD, mobile phone, etc.

[0143] Optionally, an electromagnetic wave signal is obtained, and the electromagnetic wave signal is expressed as:

[0144] ,in, is the frequency, is the voltage amplitude, For frequency and time The transmitted signal is obtained; the reflected signal generated after the reflection time is obtained, and the reflected signal is expressed as:

[0145] ,in, is the reflection time, For frequency and reflection time The reflected signal, is the reflection coefficient.

[0146] Optionally, the reflected signal is complexed to obtain a complexed reflected signal, and the complexed reflected signal is:

[0147] ,in, is the reflection coefficient.

[0148] Optionally, a time domain reflection signal is obtained according to the complex basis reflection signal, and the calculation formula is: ,in, is the time domain reflection signal, is the complexation reflection signal, Inverse Fourier transform operator symbol.

[0149] Optionally, the time domain reflection signal is calculated to obtain:

[0150] ,

[0151] in, , , is the bandwidth, is the center frequency, is the sine function:

[0152] .

[0153] Optionally, the modulus of the time domain reflection signal is obtained. The modulus of the time domain reflection signal is:

[0154] ,

[0155] make , then we get the reflection coefficient relative to time The analytical expression of is:

[0156] .

[0157] Optionally, calculate the apparent dielectric constant using the formula ,in, is the apparent dielectric constant, is the speed of light, is the probe length, is the reflection time interval; the soil volume moisture content is calculated using the first calculation formula or the second calculation formula, wherein the first calculation formula is: , the second calculation formula is: , is the volumetric moisture content of soil.

[0158] The present application also provides a computer program product, which, when executed on a data processing device, is adapted to execute a program that initializes at least the following method steps: transmitting a frequency of a probe placed in the soil to a probe placed in the soil arrive The frequency-converted electromagnetic wave signal is received to obtain a corresponding frequency-converted reflected signal, and the frequency-converted reflected signal is complexed to obtain a complex-based reflected signal, wherein: is the minimum value of frequency, is the maximum value of the frequency; perform inverse Fourier transform on the complex reflected signal to obtain the reflection coefficient formula, where the reflection coefficient formula is an analytical expression of the reflection coefficient with respect to time; obtain the reflection time interval based on the reflection coefficient formula, and the reflection time interval is the travel time of the electromagnetic wave signal along the probe obtained based on the time points of two reflections generated at the starting point and the end point when the probe is inserted into the soil; obtain the apparent dielectric constant of the soil based on the reflection time interval, and calculate the soil volume moisture content.

[0159] Optionally, an electromagnetic wave signal is obtained, and the electromagnetic wave signal is expressed as:

[0160] ,in, is the frequency, is the voltage amplitude, For frequency and time The transmitted signal is obtained; the reflected signal generated after the reflection time is obtained, and the reflected signal is expressed as:

[0161] ,in, is the reflection time, For frequency and reflection time The reflected signal, is the reflection coefficient.

[0162] Optionally, the reflected signal is complexed to obtain a complexed reflected signal, and the complexed reflected signal is:

[0163] ,in, is the reflection coefficient.

[0164] Optionally, a time domain reflection signal is obtained according to the complex basis reflection signal, and the calculation formula is: ,in, is the time domain reflection signal, is the complexation reflection signal, Inverse Fourier transform operator symbol.

[0165] Optionally, the time domain reflection signal is calculated to obtain:

[0166] ,

[0167] in, , , is the bandwidth, is the center frequency, is the sine function:

[0168] .

[0169] Optionally, the modulus of the time domain reflection signal is obtained. The modulus of the time domain reflection signal is:

[0170] ,

[0171] make , then we get the reflection coefficient relative to time The analytical expression of is:

[0172] .

[0173] Optionally, calculate the apparent dielectric constant using the formula ,in, is the apparent dielectric constant, is the speed of light, is the probe length, is the reflection time interval; the soil volume moisture content is calculated using the first calculation formula or the second calculation formula, wherein the first calculation formula is: , the second calculation formula is: , is the volumetric moisture content of soil.

[0174] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order than here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0175] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0176] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0177] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0178] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0179] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0180] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0181] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0182] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0183] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for measuring soil moisture, characterized in that: include: The frequency of the transmission to the probe placed in the soil is given by arrive The frequency-converted electromagnetic wave signal is received to obtain a corresponding frequency-converted reflected signal, and the frequency-converted reflected signal is complexed to obtain a complex-based reflected signal, wherein: is the minimum value of the frequency, is the maximum value of the frequency; Performing an inverse Fourier transform on the complex basis reflection signal to obtain a reflection coefficient formula, wherein the reflection coefficient formula is an analytical expression of the reflection coefficient relative to time; Obtaining the reflection time interval according to the reflection coefficient formula, wherein the reflection time interval is the travel time of the electromagnetic wave signal propagating along the probe according to the time points of two reflections generated at the starting point and the end point of the probe being inserted into the soil; The apparent dielectric constant of the soil is obtained according to the reflection time interval, and the volumetric moisture content of the soil is calculated.

2. The method according to claim 1, characterized in that: The frequency of the transmission to the probe placed in the soil is given by arrive The method comprises: receiving a frequency-converted electromagnetic wave signal to obtain a corresponding frequency-converted reflected signal, and complexing the frequency-converted reflected signal to obtain a complex-based reflected signal, including: The electromagnetic wave signal is obtained, where the electromagnetic wave signal is expressed as: ， in, is the frequency, is the voltage amplitude, For the frequency and time The transmission signal; The reflection signal generated after the reflection time is obtained, and the reflection signal is expressed as: ， in, is the reflection time, For the frequency and the reflection time The reflected signal, is the reflection coefficient.

3. The method according to claim 1, characterized in that: The frequency of the transmission to the probe placed in the soil is given by arrive The method comprises: receiving a frequency-converted electromagnetic wave signal to obtain a corresponding frequency-converted reflected signal, and complexing the frequency-converted reflected signal to obtain a complex-based reflected signal, including: The reflected signal is complexed to obtain the complexed reflected signal, wherein the complexed reflected signal is: ， in, is the reflection coefficient.

4. The method according to claim 3, characterized in that Perform inverse Fourier transform on the complex basis reflection signal to obtain the reflection coefficient formula, including: The time domain reflection signal is obtained according to the complex basis reflection signal, and the calculation formula is: ， in, is the time domain reflection signal, is the complexation reflection signal, Inverse Fourier transform operator symbol.

5. The method according to claim 4, characterized in that Perform inverse Fourier transform on the complex basis reflection signal to obtain the reflection coefficient formula, including: The time domain reflection signal is calculated to obtain: ， in, , , is the bandwidth, is the center frequency, is the sine function: 。 6. The method according to claim 5, characterized in that Perform inverse Fourier transform on the complex basis reflection signal to obtain the reflection coefficient formula, including: The modulus of the time domain reflection signal is obtained, where the modulus of the time domain reflection signal is: ， make , then the reflection coefficient relative to time is obtained The analytical expression of is: 。 7. The method according to claim 1, characterized in that Obtaining the apparent dielectric constant of the soil according to the reflection time interval, and calculating the soil volume moisture content, including: Calculate the apparent dielectric constant using the formula: ,in, is the apparent dielectric constant, is the speed of light, is the probe length, is the reflection time interval; The soil volume moisture content is calculated using a first calculation formula or a second calculation formula, wherein the first calculation formula is: , the second calculation formula is: , is the volume moisture content of the soil.

8. A device for measuring soil moisture, characterized in that: include: The transmitting unit is used to transmit a frequency of arrive The frequency-converted electromagnetic wave signal is received to obtain a corresponding frequency-converted reflected signal, and the frequency-converted reflected signal is complexed to obtain a complex-based reflected signal, wherein: is the minimum value of the frequency, is the maximum value of the frequency; A transformation unit performs an inverse Fourier transform on the complex basis reflection signal to obtain a reflection coefficient formula, wherein the reflection coefficient formula is an analytical expression of the reflection coefficient relative to time; An acquisition unit, which acquires a reflection time interval according to a reflection coefficient formula, wherein the reflection time interval is a travel time of the electromagnetic wave signal propagating along the probe obtained according to the time points of two reflections generated at the starting point and the end point when the probe is inserted into the soil; The calculation unit obtains the apparent dielectric constant of the soil according to the reflection time interval, and calculates the volume moisture content of the soil.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the method for measuring soil moisture according to any one of claims 1 to 7.

10. An electronic device, characterized in that: include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include a method for measuring soil moisture according to any one of claims 1 to 7.

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