Information processing device

Abstract

An information processing device (20) comprises a control unit (21) that: acquires dielectric loss tangent information indicating the dielectric loss tangent of soil into which a signal transmitted from a satellite penetrates; acquires the value of the real part of the relative permittivity of the soil; calculates the penetration depth of the signal into the soil using the value of the real part, the dielectric loss tangent of the soil, and the wavelength of the signal; and when the calculated penetration depth is equal to or greater than a predetermined value, determines to measure the moisture content of the soil using the signal.

Description

Information processing device

[0001] The present disclosure relates to an information processing device.

[0002] There are currently techniques for measuring the moisture content of soil. A typical method is the TDR method, in which a sensor is inserted into the soil. TDR is an abbreviation for Time-Domain Reflectometry. This method measures the real part of the relative dielectric constant of the soil, ε' s This method determines soil moisture content from the relationship between the volumetric water content of soil and the soil's volumetric water content. This method requires the installation of multiple sensors to measure an area, which is economically inefficient. In response to this, methods have been developed for remotely estimating soil moisture content using satellite technology. For example, Non-Patent Document 1 discloses a method for estimating soil moisture content from SNR data of signals from GNSS satellites using a positioning antenna. GNSS stands for Global Navigation Satellite System, and SNR stands for Signal-to-Noise Ratio. This method estimates soil moisture content over a wide area depending on the height of the positioning antenna, without using a dedicated sensor.

[0003] Larson, KM, Braun, JJ, Small, EE, Zavorotny, VU, Gutmann, ED, & Bilich, AL (2010). GPS Multipath and Its Relation to Near-Surface Soil Moisture Content. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 3, 91-99

[0004] In Non-Patent Document 1, the SNR waveform measured by a GNSS receiver is subjected to a quadratic equation to remove the influence of direct waves, and then each parameter is measured by regressing the waveform on a cosine curve using the following equation 1.

[0005]

[0006] In Equation 1, A is the amplitude, h is the height from the effective reflecting surface to the antenna, λ is the wavelength, E is the elevation angle of the GNSS satellite, and φ (rad) is the phase shift. Non-Patent Document 1 proposes that h and φ are correlated with the soil moisture content θ, and that the soil moisture content θ can be estimated from the SNR. Furthermore, for example, Reference 1 below proposes the following equation 2, which is a relationship between φ (deg) and θ, based on experiments and simulations.

[0007] [Reference 1] Chew, C., Small, E., Larson, K., Zavorotny, V., 2014. Effects of Near-Surface Soil Moisture on GPS SNR Data: Development of a Retrieval Algorithm for Soil Moisture. Geoscience and Remote Sensing, IEEE Transactions on. 52, 537-543

[0008] When measuring soil moisture content θ using signals from a satellite, the electromagnetic waves do not penetrate the soil, making it difficult to measure accurately. As such, there is room for improvement in the technology for remotely measuring soil moisture content.

[0009] In view of the above circumstances, an object of the present disclosure is to improve the technology for remotely measuring the moisture content of soil.

[0010] An information processing device according to one embodiment includes a control unit that acquires dielectric loss tangent information indicating the dielectric loss tangent of soil through which a signal transmitted from a satellite penetrates, acquires the value of the real part of the relative dielectric constant of the soil, calculates the penetration depth of the signal into the soil using the value of the real part, the dielectric loss tangent of the soil, and the wavelength of the signal, and decides to measure the moisture content of the soil using the signal if the calculated penetration depth is equal to or greater than a predetermined value.

[0011] The present disclosure makes it possible to improve techniques for remotely measuring soil moisture content.

[0012] FIG. 1 is a block diagram showing the configuration of a system according to a first embodiment; FIG. 2 is a diagram for explaining reception of a signal by an antenna; FIG. 3 is a flowchart showing an example of operation of an information processing device according to the first embodiment; FIG. 4 is a diagram showing an example of soil sample information; FIG. 5 is a flowchart showing an example of operation of an information processing device according to a second embodiment; FIG. 6 is a graph showing the relationship between the value of the real part of the relative dielectric constant and the corresponding penetration depth according to a modified example.

[0013] First Embodiment Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings.

[0014] In each drawing, the same or corresponding parts are denoted by the same reference numerals. In the description of this embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

[0015] The configuration of a system 1 according to this embodiment will be described with reference to FIG.

[0016] The system 1 includes at least one antenna 10 and at least one information processing device 20. Although antennas 10A to 10C are shown as the antenna 10 in Fig. 1, the number of antennas is not limited to this.

[0017] The antenna 10 is an antenna capable of receiving signals transmitted from GNSS satellites. The antenna 10 may be a general-purpose positioning antenna. For example, the antenna 10 may be used as an electronic reference point installed at any location in an area subject to satellite positioning. The antenna 10 is capable of transmitting information generated based on the received signals to the information processing device 20. Examples of GNSS include at least one of the Global Positioning System (GPS), the Quasi-Zenith Satellite System (QZSS), BeiDou, the Global Navigation Satellite System (GLONASS), and Galileo.

[0018] The information processing device 20 is, for example, a general-purpose computer such as a PC or a tablet, a server computer such as a cloud server, or a dedicated computer. "PC" is an abbreviation for personal computer.

[0019] The network 30 may include the Internet, at least one WAN, at least one MAN, or a combination thereof. "WAN" is an abbreviation for wide area network. "MAN" is an abbreviation for metropolitan area network. The network 30 may include at least one wireless network, at least one optical network, or a combination thereof. The wireless network may be, for example, an ad-hoc network, a cellular network, a wireless LAN, a satellite communication network, or a terrestrial microwave network. "LAN" is an abbreviation for local area network.

[0020] An outline of this embodiment will be described with reference to Figures 1 and 2. An information processing device 20 acquires dielectric loss tangent information indicating the dielectric loss tangent tanδ of the soil through which a signal transmitted from a satellite G1 penetrates. The information processing device 20 acquires a value ε' of the real part of the relative dielectric constant of the soil. s and obtain the real part value ε′ s The information processing device 20 calculates the penetration depth D of the signal into the soil using the dielectric loss tangent tanδ of the soil and the wavelength λ of the signal. If the calculated penetration depth D is equal to or greater than a predetermined value, the information processing device 20 determines to measure the moisture content θ of the soil using the signal.

[0021] 2, the antenna 10 generates signal information indicating the SNR of a received signal, which includes a satellite signal S1 transmitted from a satellite G1 and a reflected signal S2 generated when the satellite signal S1 is reflected by a reflecting surface R in the soil of the land where the antenna 10 is installed, and transmits the signal information to the information processing device 20. The information processing device 20 receives the signal SNR of a received signal including a satellite signal S1 transmitted from a satellite G1 and a reflected signal S2 generated when the satellite signal S1 is reflected by a reflecting surface R in the soil of the land where the antenna 10 is installed. antand measures the soil moisture content θ using the penetration depth D of the satellite signal S1 into the soil before the reflected signal S2 is generated. For example, the information processing device 20 performs SNR fitting using the vertical distance H between the phase center point C of the antenna 10 and the reflecting surface R corresponding to the reflected signal S2, measures each parameter, and measures the soil moisture content θ. If the penetration depth D is sufficient, that is, if the satellite signal S1 transmitted from the satellite G1 travels a long distance through the soil, the value ε' of the real part of the relative dielectric constant of the soil s The antenna 10 can acquire a delayed reflected signal S2 due to the influence of the SNR. In this case, the parameters obtained by fitting the SNR change, and as a result, the information processing device 20 can measure the soil moisture content θ with high accuracy. On the other hand, if there is not enough penetration depth D, the value ε' of the real part of the relative dielectric constant s Since the influence of the above is small, it becomes difficult to measure the soil moisture content θ with high accuracy.

[0022] According to this embodiment, compared to a case where the soil moisture content θ is measured uniformly for any soil, it is possible to achieve area measurement of the soil moisture content θ by the information processing device 20 while ensuring a certain level of accuracy in the measurement results. Therefore, it is possible to improve the technology for remotely measuring soil moisture content.

[0023] The configuration of the information processing device 20 according to this embodiment will be described with reference to Fig. 1 again. The information processing device 20 includes a control unit 21, a storage unit 22, a communication unit 23, an input unit 24, and an output unit 25.

[0024] The control unit 21 includes at least one processor, at least one programmable circuit, at least one dedicated circuit, or any combination thereof. The processor is a general-purpose processor such as a CPU or GPU, or a dedicated processor specialized for specific processing. "CPU" is an abbreviation for central processing unit. "GPU" is an abbreviation for graphics processing unit. An example of the programmable circuit is an FPGA. "FPGA" is an abbreviation for field-programmable gate array. An example of the dedicated circuit is an ASIC. "ASIC" is an abbreviation for application specific integrated circuit. The control unit 21 executes processing related to the operation of the information processing device 20 while controlling each unit of the information processing device 20.

[0025] The storage unit 22 includes at least one semiconductor memory, at least one magnetic memory, at least one optical memory, or any combination thereof. The semiconductor memory is, for example, a RAM, a ROM, or a flash memory. "RAM" is an abbreviation for random access memory. "ROM" is an abbreviation for read only memory. RAM is, for example, an SRAM or a DRAM. "SRAM" is an abbreviation for static random access memory. "DRAM" is an abbreviation for dynamic random access memory. ROM is, for example, an EEPROM. "EEPROM" is an abbreviation for electrically erasable programmable read only memory. Flash memory is, for example, an SSD. "SSD" is an abbreviation for solid-state drive. Magnetic memory is, for example, an HDD. "HDD" is an abbreviation for hard disk drive. The storage unit 22 functions, for example, as a main storage device, an auxiliary storage device, or a cache memory. The storage unit 22 stores information used in the operation of the information processing device 20 and information obtained by the operation of the information processing device 20 .

[0026] The communication unit 23 includes at least one communication module. The communication module is, for example, a module compatible with a wired LAN communication standard such as Ethernet (registered trademark), a wireless LAN communication standard such as IEEE 802.11, or a mobile communication standard such as LTE, 4G standard, or 5G standard. "IEEE" is an abbreviation for Institute of Electrical and Electronics Engineers. "LTE" is an abbreviation for Long Term Evolution. "4G" is an abbreviation for 4th generation. "5G" is an abbreviation for 5th generation. The communication unit 23 receives information used in the operation of the information processing device 20 and transmits information obtained by the operation of the information processing device 20.

[0027] The input unit 24 includes at least one input interface. The input interface is, for example, a physical key, a capacitance key, a pointing device, a touch screen integrated with a display, or a microphone. The input unit 24 accepts an operation to input information used in the operation of the information processing device 20. The input unit 24 may be connected to the information processing device 20 as an external input device instead of being provided in the information processing device 20. As a connection method, any method such as a Universal Serial Bus (USB), a High-Definition Multimedia Interface (HDMI) (registered trademark), or Bluetooth (registered trademark) can be used.

[0028] The output unit 25 includes at least one output interface. The output interface is, for example, a display or a speaker. The display is, for example, an LCD (Liquid Crystal Display) or an organic EL (Electro Luminescent) display. The output unit 25 outputs information obtained by the operation of the information processing device 20. The output unit 25 may be connected to the information processing device 20 as an external output device instead of being provided in the information processing device 20. As a connection method, any method such as USB, HDMI (registered trademark), or Bluetooth (registered trademark) can be used.

[0029] The functions of the information processing device 20 are realized by executing a program according to this embodiment on a processor serving as the control unit 21. That is, the functions of the information processing device 20 are realized by software. The program causes a computer to execute the operations of the information processing device 20, thereby causing the computer to function as the information processing device 20. That is, the computer functions as the information processing device 20 by executing the operations of the information processing device 20 in accordance with the program.

[0030] The program can be stored on a non-transitory computer-readable medium. Examples of the non-transitory computer-readable medium include flash memory, magnetic recording devices, optical disks, magneto-optical recording media, and ROMs. The program can be distributed by selling, transferring, or lending portable media such as SD cards, DVDs, or CD-ROMs that store the program. "SD" is an abbreviation for Secure Digital. "DVD" is an abbreviation for digital versatile disc. "CD-ROM" is an abbreviation for compact disc read only memory. The program can also be distributed by storing it in the storage of a server and transferring it from the server to another computer. The program can also be provided as a program product.

[0031] A computer temporarily stores a program stored on a portable medium or transferred from a server in its main storage device. The computer then reads the program stored in the main storage device with its processor and executes processing in accordance with the read program. The computer may also read the program directly from the portable medium and execute processing in accordance with the program. The computer may also execute processing in accordance with the received program each time a program is transferred from the server to the computer. Processing may also be executed using a so-called ASP-type service that realizes functions simply by issuing execution instructions and obtaining results, without transferring the program from the server to the computer. "ASP" is an abbreviation for application service provider. A program is information used for processing by a computer and includes something equivalent to a program. For example, data that is not a direct instruction to a computer but has properties that define computer processing falls under the category of "something equivalent to a program."

[0032] Some or all of the functions of the information processing device 20 may be realized by a programmable circuit or a dedicated circuit as the control unit 21. In other words, some or all of the functions of the information processing device 20 may be realized by hardware.

[0033] Next, the operation of the information processing device 20 according to this embodiment will be described with reference to Figures 3 and 4. The operation of the information processing device 20 corresponds to a method according to this embodiment. In this embodiment, it is assumed that the information processing device 20 acquires, from the antenna 10, signal information indicating the SNR of the received signal, which includes the satellite signal S1 and the reflected signal S2, received by the antenna 10.

[0034] In step S101, the control unit 21 of the information processing device 20 acquires information indicating the wavelength λ of the signal transmitted from the satellite G1. For example, the control unit 21 may remove the trend of the SNR indicated by the signal information acquired from the antenna 10, and then acquire information indicating the wavelength λ when fitting to a cosine curve using the above-mentioned Equation 1. Without being limited to this, the control unit 21 may, for example, accept user input of the information via the input unit 24.

[0035] In step S102, the control unit 21 acquires dielectric loss tangent information indicating the dielectric loss tangent tanδ of the soil to be measured. The dielectric loss tangent tanδ is an index that indicates the degree of loss of electrical energy when an AC electric field is applied to a dielectric. The dielectric loss tangent tanδ is calculated by multiplying the value ε″ of the imaginary part of the relative dielectric constant by the following equation 3: s and the real part of the relative permittivity ε' s This is a value that can be calculated as a ratio of

[0036]

[0037] Any method may be used to acquire the dielectric loss tangent information. For example, the control unit 21 reads out soil sample information indicating a plurality of soil samples and the default dielectric loss tangent tanδ corresponding to each of the plurality of soil samples from the storage unit 22. The control unit 21 selects a soil sample from the plurality of soil samples that corresponds to the soil to be measured. The control unit 21 acquires the dielectric loss tangent information by reading out the default dielectric loss tangent tanδ corresponding to the selected soil sample from the soil sample information. For example, the control unit 21 may read out the average value of the default dielectric loss tangent tanδ indicated in the soil sample information.

[0038] The soil sample information may be recorded based on the information described in Reference 2, for example. [Reference 2] Cihlar, J., Ulaby, FT, 1974. Dielectric properties of soils as a function of moisture content. Remote Sensing Laboratory RSL Technical Report. 177.

[0039] FIG. 4 is a diagram showing an example of soil sample information. While FIG. 4 shows the soil sample information in a table format, the format of the soil sample information is not limited to this. The soil sample information includes information on the soil sample and the soil moisture content θ (g / cm ３ The range of the dielectric loss tangent (tanδ) is recorded in association with the representative value, maximum value, minimum value, and standard deviation of the default dielectric loss tangent (tanδ). The soil samples specifically include sand, silt, clay, etc. The particle sizes are sand, silt, and clay in descending order, and as can be seen from FIG. 4, the smaller the particle size, the larger the default dielectric loss tangent (tanδ).

[0040] The maximum value of the range of the soil moisture content θ is the saturated volumetric water content of the soil sample. The range of the soil moisture content θ may be a general value obtained by testing or the like.

[0041] The soil sample information may be recorded for each frequency. In this case, the control unit 21 may calculate the frequency corresponding to the wavelength λ indicated by the information acquired in S101 and read out the soil sample information related to the calculated frequency. For example, the control unit 21 may receive a frequency input from the user via the input unit 24 and read out the soil sample information related to that frequency. Figure 4 shows soil sample information related to the 1.3 GHz frequency.

[0042] For example, the control unit 21 receives a user's selection of a soil sample corresponding to the soil to be measured via the input unit 24. In this case, the soil sample may be selected based on the results of a particle size test conducted on the soil to be measured. The particle size test may include, for example, a sieve analysis or a sedimentation test conducted on the soil in accordance with JIS A1204. "JIS" is an abbreviation for Japanese Industrial Standards.

[0043] As another example of a method for acquiring the dielectric loss tangent information, the control unit 21 may acquire information indicating the measured dielectric loss tangent tanδ obtained by measurement using a vector network analyzer as the dielectric loss tangent information. The vector network analyzer calculates the value ε″ of the imaginary part of the relative dielectric constant. s and the real part of the relative permittivity ε' sThis measuring instrument can directly measure the complex dielectric constant, i.e., the dielectric loss tangent tanδ, of soil. The control unit 21 may receive a user input of the measured dielectric loss tangent tanδ obtained by measuring soil using a vector network analyzer via the input unit 24, and acquire the dielectric loss tangent information. The control unit 21 may communicate with the vector network analyzer via the communication unit 23 and acquire the dielectric loss tangent information directly from the vector network analyzer. According to the above-mentioned particle size test, in the case of volcanic ash soil or soil containing high salinity, factors other than particle shape may affect the dielectric loss tangent tanδ, which may lead to errors in the dielectric loss tangent tanδ. However, using a vector network analyzer makes it possible to acquire more accurate dielectric loss tangent information.

[0044] In step S103, the control unit 21 calculates the real part ε' of the relative dielectric constant of the soil. s Obtain information indicating the

[0045] The real part of the dielectric constant ε' s Any method may be employed to acquire information indicating the relative dielectric constant. For example, when the dielectric loss tangent information is acquired by referring to the soil sample information described above, the control unit 21 acquires the value ε' of the real part of the relative dielectric constant based on the maximum value of the water content θ of the soil of the selected soil sample. s In this case, the control unit 21 obtains the information by calculating, for example, the value ε′ of the real part of the relative dielectric constant. s The maximum value of the soil moisture content θ is substituted into the following equation 4, which shows the relationship between the relative permittivity and the soil moisture content θ, and the real part of the relative permittivity ε' is calculated. s As a result, under the assumption that the moisture content θ of the soil to be measured is the maximum value, the penetration depth D can be derived as described below, and it becomes possible to determine whether or not to perform measurement using the information processing device 20 while reducing the risk of determining that soil that is actually unsuitable for measurement is suitable for measurement.

[0046]

[0047] Details of Equation 4 are described in, for example, Reference 3, and therefore will not be explained in detail here. [Reference 3] Topp, GC, JL Davis, and AP Annan (1980), Electromagnetic determination of soil water content: Measurements in coaxial transmission lines, Water Resour. Res., 16(3), 574-582, doi:10.1029 / WR016i003p00574

[0048] For example, when the information indicating the measured dielectric loss tangent tanδ is acquired as the dielectric loss tangent information, the control unit 21 calculates the value ε′ of the real part of the relative dielectric constant measured by the vector network analyzer. s By receiving the user's input via the input unit 24, the value ε' of the real part of the relative dielectric constant is obtained. s The control unit 21 may communicate with the vector network analyzer via the communication unit 23 and obtain the information directly from the vector network analyzer.

[0049] In step S104, the control unit 21 calculates the value ε′ of the real part of the relative dielectric constant acquired in step S103. s The penetration depth D of the signal into the soil is calculated using the dielectric loss tangent tan δ indicated by the dielectric loss tangent information acquired in step S102 and the wavelength λ indicated by the information acquired in step S101.

[0050] Any method may be adopted to calculate the penetration depth D. In this embodiment, the control unit 21 calculates the value ε′ of the real part of the relative dielectric constant in Equation 6 obtained by substituting Equation 3, which is shown again below, into Equation 5. s and the dielectric loss tangent tanδ indicated by the dielectric loss tangent information are substituted to calculate the penetration depth D. Equation 6 is expressed as follows: s、 and the dielectric loss tangent tanδ.

[0051]

[0052] Details of Equation 5 are described in, for example, Reference 4, and therefore will not be described in detail here. [Reference 4] Njoku, EG, Entekhabi, D., 1996. Passive microwave remote sensing of soil moisture. Journal of Hydrology. 184, 101-129.

[0053] In step S105, the control unit 21 determines whether the calculated penetration depth D is equal to or greater than a predetermined value. If it is equal to or greater than the predetermined value, the processing of the control unit 21 proceeds to step S106. If it is less than the predetermined value, the processing of the control unit 21 proceeds to step S107. The predetermined value may be set in advance by the user and stored in the memory unit 22. The predetermined value is, for example, 0.5 cm. The control unit 21 may output information indicating whether the calculated penetration depth D is equal to or greater than the predetermined value via the output unit 25. For example, the control unit 21 may output the information by transmitting the information to the user's terminal device via the communication unit 23.

[0054] In step S106, the control unit 21 determines to measure the soil moisture content θ using the signal received by the antenna 10. That is, the control unit 21 determines to measure the soil moisture content θ using a signal transmitted from the satellite G1. The soil moisture content θ may be measured, for example, by removing the SNR trend indicated by the signal information acquired from the antenna 10, and then fitting the signal to a cosine curve using the above-mentioned Equation 1, using parameters obtained by, for example, Equation 2. The soil moisture content θ may be measured by the control unit 21, or by another device in accordance with an instruction from the control unit 21. The control unit 21 may notify the user who is to measure the soil moisture content θ that measurement has been decided via the output unit 25. For example, the control unit 21 may transmit information indicating the decision to measure to the user's terminal device via the communication unit 23. The operation of the control unit 21 then ends.

[0055] In step S107, the control unit 21 determines not to measure the soil moisture content θ using the signal received by the antenna 10. That is, the control unit 21 determines not to measure the soil moisture content θ, or to measure the soil moisture content θ without using the signal transmitted from the satellite G1. The operation of the control unit 21 then ends.

[0056] Second Embodiment A second embodiment of the present disclosure will now be described.

[0057] The configuration of the system 1 according to this embodiment is the same as that of the first embodiment shown in Fig. 1, and therefore a description thereof will be omitted. The configurations of the antenna 10 and the information processing device 20 according to this embodiment are also the same as those of the first embodiment, and therefore a description thereof will be omitted.

[0058] The operation of the information processing device 20 according to the second embodiment will be described with reference to FIGS. 4, 5A, and 5B.

[0059] Step S201 is the same as step S101 in FIG. 3, and therefore a description thereof will be omitted.

[0060] In step S202, the control unit 21 reads out soil sample information from the storage unit 12. The soil sample information according to this embodiment is the soil sample information shown in FIG. 4. The control unit 21 selects a soil sample from a plurality of soil samples that corresponds to the soil to be measured. The control unit 21 acquires the dielectric loss tangent information by reading out the default dielectric loss tangent tanδ corresponding to the selected soil sample from the soil sample information. The control unit 21 may, for example, read out the average value of the default dielectric loss tangent tanδ indicated in the soil sample information.

[0061] In step S203, the control unit 21 calculates the real part value ε′ using the above-mentioned equation 4 based on the maximum value of the soil moisture content θ of the selected soil sample. s By calculating the real part of the relative permittivity of the soil, ε′ s Obtain information indicating the

[0062] In step S204, the control unit 21 calculates the value ε′ of the real part of the relative dielectric constant acquired in step S203. sUsing the default dielectric tangent tanδ indicated by the dielectric tangent information acquired in step S202 and the wavelength λ indicated by the information acquired in step S201, the penetration depth D of the signal into the soil is calculated using the above-mentioned equation 6.

[0063] In step S205, the control unit 21 determines whether the calculated penetration depth D is equal to or greater than a predetermined value. If it is equal to or greater than the predetermined value, the process of the control unit 21 proceeds to step S210. If it is less than the predetermined value, the process of the control unit 21 proceeds to step S206. The predetermined value may be set in advance by the user and stored in the storage unit 22.

[0064] In step S206, the control unit 21 acquires, as dielectric loss tangent information, information indicating the measured dielectric loss tangent tanδ obtained by measurement using the vector network analyzer. The control unit 21 may accept, via the input unit 24, a user input of the measured dielectric loss tangent tanδ obtained by measuring the soil using the vector network analyzer, and acquire the dielectric loss tangent information. The control unit 21 may communicate with the vector network analyzer via the communication unit 23 and acquire the dielectric loss tangent information directly from the vector network analyzer.

[0065] In step S207, the control unit 21 calculates the real part ε' of the relative dielectric constant measured by the vector network analyzer. s The control unit 21 acquires information indicating the value ε′ of the real part of the relative dielectric constant measured by the vector network analyzer. s By receiving the user's input via the input unit 24, the value ε' of the real part of the relative dielectric constant is obtained. s The control unit 21 may communicate with the vector network analyzer via the communication unit 23 and obtain the information directly from the vector network analyzer.

[0066] In step S208, the control unit 21 calculates the value ε′ of the real part of the relative dielectric constant acquired in step S207. s Using the measured dielectric tangent tanδ indicated by the dielectric tangent information acquired in step S206 and the wavelength λ indicated by the information acquired in step S201, the penetration depth D of the signal into the soil is calculated using the above-mentioned equation 6.

[0067] In step S209, the control unit 21 determines whether the calculated penetration depth D is equal to or greater than a predetermined value. If it is equal to or greater than the predetermined value, the control unit 21 proceeds to step S210. If it is less than the predetermined value, the control unit 21 proceeds to step S211. The predetermined value may be the same as the value used in step S205.

[0068] Step S210 is similar to step S106 in FIG. 3, and therefore a description thereof will be omitted.

[0069] Step S211 is similar to step S107 in FIG. 3, and therefore a description thereof will be omitted.

[0070] According to this embodiment, the control unit 21 first calculates the penetration depth D using the default dielectric tangent tanδ, which has the lowest acquisition cost, and determines whether the penetration depth D is less than a predetermined value. If the penetration depth D is less than the predetermined value, the control unit 21 further acquires a measured dielectric tangent tanδ, recalculates the penetration depth D, and determines again whether the penetration depth D is equal to or greater than the predetermined value. This allows the control unit 21 to recalculate a more precise penetration depth D using a value obtained by a vector network analyzer only when it is determined that the soil moisture content θ cannot be measured with the penetration depth D calculated using default information. This makes it possible to maintain measurement accuracy while minimizing the cost associated with determining whether to measure the soil moisture content θ.

[0071] The present disclosure is not limited to the above-described embodiments. For example, two or more blocks shown in the block diagram may be integrated, or one block may be divided. Two or more steps shown in the flowchart may be executed in parallel or in a different order, instead of being executed in chronological order as described, depending on the processing capabilities of the device executing each step, or as needed. Other modifications are possible within the scope of the present disclosure.

[0072] As a modified example of the present disclosure, in the above-described S103 or S203, the control unit 21 of the information processing device 20 calculates the value ε′ of the real part of the relative dielectric constant for all values ​​in the range of the water content θ of the soil indicated by the soil sample information. s That is, the control unit 21 may calculate the value ε′ of the real part of the relative dielectric constant.s In this case, the control unit 21 may calculate a plurality of values ​​ε′ of the real part of the relative dielectric constant calculated in the above-mentioned S104 or S204. s The control unit 21 may further determine whether or not all of the calculated penetration depths D are equal to or greater than a predetermined value in the above-described S105 or S205.

[0073] FIG. 6 shows a plurality of real part values ​​ε′ of relative dielectric constants calculated by the control unit 21 for sand, silt, and clay when the wavelength λ is 19.0 cm and 24.4 cm, respectively. s 6 is an example of a graph showing the relationship between the value of the real part of the relative dielectric constant ε' and the value of the real part of the relative dielectric constant ε' for silt. In FIG. 6, the penetration depth D for a wavelength of 19.0 cm is shown as 19SD for sand, 19ST for silt, and 19C for clay. The penetration depth D for a wavelength of 24.4 cm is shown as 24SD for sand, 24ST for silt, and 24C for clay. The predetermined value set by the user in advance is 1 cm, and is shown by a dashed line. Referring to FIG. 6, the penetration depth D for silt 24ST for a wavelength of 24.4 cm is shown as ε' for the real part of the relative dielectric constant s It can be seen that the penetration depth D is equal to or greater than the predetermined value of 1 cm in all regions. Therefore, similar to S106 described above, the control unit 21 can determine to measure the moisture content θ of the soil. On the other hand, for the silt 19ST when the wavelength is 19.0 cm, the value ε' of the real part of the relative dielectric constant s is the value ε' of the real part of the relative dielectric constant indicated by X in FIG. s From this value onward, it can be seen that the penetration depth D is less than the predetermined value of 1 cm, i.e., the soil is wetter. Therefore, similar to S107 described above, the control unit 21 can decide not to measure the soil moisture content θ.

[0074] The control unit 21 may store the graph of Figure 6 in the memory unit 22 and display it on a display serving as the output unit 25 in response to a user request. The control unit 21 may also transmit information showing the graph to a terminal device used by the user via the communication unit 23. Generally, the wavelength λ affects the cost of the antenna 10, and while a signal with a wavelength λ of 19.0 cm can be measured with an economical antenna 10, a signal with a wavelength λ of 24.4 cm tends to require an expensive and precise antenna 10. According to this modification, by referring to the graph of Figure 6 displayed on the output unit 25, the user can easily consider the specifications of the antenna 10 to be installed.

[0075] REFERENCE SIGNS LIST 1 System 10 Antenna 20 Information processing device 21 Control unit 22 Storage unit 23 Communication unit 24 Input unit 25 Output unit 30 Network

Claims

1. An information processing device comprising: a control unit that acquires dielectric loss tangent information indicating the dielectric loss tangent of soil through which a signal transmitted from a satellite penetrates; acquires the value of the real part of the relative dielectric constant of the soil; calculates the penetration depth of the signal into the soil using the value of the real part, the dielectric loss tangent of the soil, and the wavelength of the signal; and decides to measure the moisture content of the soil using the signal if the calculated penetration depth is equal to or greater than a predetermined value.

2. The information processing device according to claim 1, wherein the control unit acquires, as the dielectric loss tangent information, information indicating a measured dielectric loss tangent obtained by measurement using a vector network analyzer.

3. An information processing device as described in claim 1, further comprising a memory unit storing soil sample information indicating a plurality of soil samples and a default dielectric tangent corresponding to each of the plurality of soil samples, wherein the control unit selects a soil sample corresponding to the soil from the plurality of soil samples, and obtains the dielectric tangent information by reading information indicating the default dielectric tangent corresponding to the selected soil sample from the memory unit.

4. The information processing device described in claim 3, wherein the control unit acquires information indicating a measured dielectric tangent obtained by measurement using a vector network analyzer when the calculated penetration depth is less than the predetermined value, recalculates the penetration depth of the soil using the measured dielectric tangent, and when the recalculated penetration depth is equal to or greater than the predetermined value, decides to measure the moisture content of the soil using the signal.

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