Information processing device, method for processing information, and program

Abstract

To improve a technique of remotely measuring the moisture content of a soil by using measurement data with a GNSS.SOLUTION: A information processing device 20 includes a control unit 21 for acquiring height information indicating the height of an antenna 10 receiving a satellite signal transmitted from a satellite, and signal information indicating the signal-to-noise ratio of a received signal including the satellite signal and a reflection signal generated by the reflection of the satellite signal in the soil of the ground where the antenna is set, received by the antenna, estimating a penetration depth representing the depth to which the satellite signal penetrated into the soil before the reflection signal is generated, on the basis of the acquired height information and signal information; and calculating the water content of the soil by using the obtained estimated value of the penetration depth.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an information processing device, an information processing method, and a program. [Background technology]

[0002] Conventionally, there are techniques for measuring soil moisture. A typical technique is the TDR method, in which a sensor is inserted into the soil. TDR is an abbreviation for Time-Domain Reflectometry. This method requires that a sensor be directly installed in the soil, which is costly. In contrast, in recent years, a technique for measuring soil moisture remotely using satellite technology called remote sensing has been developed. For example, a technique for measuring soil moisture using GNSS refraction signals and the like using GNSS-IR, which utilizes GNSS signals, is known. GNSS is an abbreviation for Global Navigation Satellite System, and GNSS-IR is an abbreviation for GNSS interferometric reflectometry. For example, Non-Patent Document 1 discloses a technique for measuring soil moisture using a positioning antenna. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 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 Summary of the Invention [Problem to be solved by the invention]

[0004] In Non-Patent Document 1, after removing the trend of the SNR measured by the GNSS receiver, each parameter is measured by fitting the SNR according to the following formula 1. SNR is an abbreviation for Signal-to-Noise Ratio.

[0005]

number

[0006] In Equation 1, h is the antenna height, λ is the wavelength, E is the elevation angle of the GNSS satellite, and φ is the phase shift. S Multipath waves PR are waves reflected by S FIG. 5 is a diagram for explaining how the antenna A receives the multipath wave PR. S is the surface R S According to this assumption, the multipath wave PR S does not penetrate into the ground, and h in the above formula 1 should be equal to the height of antenna A shown in FIG. 5. However, it is known that the calculated value of h is greater than the actual antenna height. In addition, in Non-Patent Document 1, soil moisture is estimated by utilizing the fact that the phase shift φ is correlated with the soil moisture content θ. However, this method is based on the principle of utilizing the relative change between the phase and the soil moisture content, that is, the relative change in the soil moisture content, and in order to obtain the absolute soil moisture content, it is necessary to measure the initial soil moisture content by collecting soil, etc. The necessity of measuring the initial soil moisture content is described, for example, in the following Reference Document 1. [Reference 1] Chew, C., Small, EE, & Larson, KM (2016). An algorithm for soil moisture estimation using GPS-interferometric reflectometry for bare and vegetated soil. GPS Solutions, 20, 525-537

[0007] In addition, conventional techniques have only been reported for dry soil with a soil moisture content of θ<0.35, and there has been a demand for technology that can measure soil moisture content θ with high accuracy even when the soil moisture content is higher. Thus, there is room for improvement in the method of measuring soil moisture content from GNSS measurement data.

[0008] In view of the above circumstances, an object of the present disclosure is to improve a method for remotely measuring soil moisture using measurement data obtained by GNSS. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the information processing device of the present disclosure includes a control unit that acquires height information indicating the height of an antenna that receives a satellite signal transmitted from a satellite, and signal information indicating the signal-to-noise ratio of a received signal received by the antenna, including the satellite signal and a reflected signal generated by the satellite signal being reflected in the soil of the land on which the antenna is installed, estimates the penetration depth of the satellite signal into the soil before the reflected signal is generated based on the acquired height information and signal information, and calculates the moisture content of the soil using the obtained estimated penetration depth.

[0010] In addition, an information processing method according to the present disclosure is an information processing method executed by an information processing device, and includes acquiring height information indicating the height of an antenna receiving a satellite signal transmitted from a satellite, and signal information indicating a signal-to-noise ratio of a received signal received by the antenna, including the satellite signal and a reflected signal generated by the satellite signal being reflected in the soil of the land on which the antenna is installed, estimating a penetration depth of the satellite signal into the soil before the reflected signal is generated based on the acquired height information and signal information, and calculating the moisture content of the soil using the obtained estimated penetration depth.

[0011] In addition, the program according to the present disclosure causes a computer to function as an information processing device according to the present disclosure. Effect of the Invention

[0012] The present disclosure makes it possible to improve the technique for remotely measuring soil moisture using GNSS measurement data. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram for explaining how an antenna receives each signal. [Diagram 3] 11A and 11B are diagrams illustrating an example of a result of calculation of a moisture amount by an information processing device. [Figure 4A] FIG. 4 is a diagram illustrating the operation of a control unit of the information processing device. [Figure 4B] FIG. 4 is a diagram illustrating the operation of a control unit of the information processing device. [Diagram 5] FIG. 1 is a diagram for explaining how an antenna receives each signal in the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals. In the description of the present 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. 1. The system 1 according to this embodiment 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.

[0016] 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 an arbitrary 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. The GNSS includes, for example, at least one of GPS (Global Positioning System), QZSS (Quasi-Zenith Satellite System), BeiDou, GLONASS (Global Navigation Satellite System), and Galileo.

[0017] The information processing device 20 is installed in a facility such as a data center. The information processing device 20 is, for example, a server belonging to a cloud computing system or another computing system.

[0018] Network 30 includes 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. 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.

[0019] The present embodiment will be outlined with reference to FIG. 1 and FIG.

[0020] In the system 1 according to this embodiment, the information processing device 20 acquires height information indicating the height h of the antenna 10 receiving the satellite signal S1 transmitted from the satellite G1, and signal information indicating the SNR of the received signal including the satellite signal S1 received by the antenna 10 and a reflected signal S2 generated by the satellite signal S1 being reflected in the soil of the land on which the antenna 10 is installed. Based on the acquired height information and signal information, the information processing device 20 estimates the penetration depth h' of the satellite signal S1 penetrating into the soil before the reflected signal S2 is generated. The information processing device 20 calculates the moisture content θ of the soil using the obtained estimated value of the penetration depth h'.

[0021] Satellite signal S1 includes a direct wave transmitted from satellite G1. Reflected signal S2 includes a multipath wave. Antenna 10 generates signal information indicating the SNR of the received signal using any SNR measurement method. Information processing device 20 estimates the penetration depth h' into the soil when satellite signal S1 is reflected in the soil to become reflected signal S2 and is received by antenna 10, and uses this to calculate the moisture content θ of the soil.

[0022] According to this embodiment, by using the existing antenna 10, it is not necessary to actually insert a sensor into the soil, nor is it necessary to measure the initial soil moisture content by sampling the soil, and it is possible to measure the absolute soil moisture content by GNSS alone. Therefore, it is possible to improve the method of measuring the soil moisture content remotely.

[0023] The configuration of an information processing device 20 according to this embodiment will be described with reference to Fig. 1. 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 is realized by a control and arithmetic circuit (controller). The control and arithmetic circuit may be configured by dedicated hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array), may be configured by a processor, or may be configured to include both. The control unit 21 executes processes related to the operation of the information processing device 20 while controlling each part of the information processing device 20. The control unit 21 can transmit and receive information to and from external devices via the communication unit 23 and the network 30.

[0025] The storage unit 22 includes one or more memories, and may include, for example, a semiconductor memory, a magnetic memory, an optical memory, etc. Each memory included in the storage unit 22 may function, for example, as a main storage device, an auxiliary storage device, or a cache memory. The storage unit 22 stores any information used for the operation of the information processing device 20. The storage unit 22 does not necessarily need to be provided inside the information processing device 20, and may be configured to be provided outside the information processing device 20.

[0026] The communication unit 23 includes at least one communication interface. The communication interface is, for example, a LAN interface. 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 communication unit 23 enables the information processing device 20 to transmit and receive information to and from other devices via the network 30 .

[0028] The input unit 24 includes at least one input interface. The input interface is, for example, a physical key, a capacitive key, a pointing device, a touch screen integral with a display, or a microphone. The input unit 24 accepts an operation to input information used for 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 USB (Universal Serial Bus), HDMI (High-Definition Multimedia Interface) (registered trademark), or Bluetooth (registered trademark) can be used.

[0029] 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, a liquid crystal display (LCD) or an organic electroluminescent (EL) 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.

[0030] A computer capable of executing program instructions can be used to function as the above-mentioned information processing device 20. Here, the computer may be a general-purpose computer, a dedicated computer, a workstation, a PC (Personal Computer), an electronic notepad, etc. The program instructions may be program code, code segments, etc. for performing necessary tasks.

[0031] In the case of using a computer, the control unit 21 includes a processor. The processor may be a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), a SoC (System on a Chip), or the like, and may be configured with a plurality of processors of the same type or different types. The processor reads out a program from the storage unit 22 and executes it to control each of the above-mentioned components and perform various arithmetic processing. Note that at least a part of the processing contents may be realized by hardware. The input unit 24 is an input interface that receives a user's input operation and acquires information based on the user's operation, and is a keyboard, a mouse, or the like. The output unit 25 is an output interface that outputs information, and is a display, a speaker, or the like. The communication unit 23 is an interface for communicating with an external device.

[0032] The program may be recorded on a computer-readable recording medium. By using such a recording medium, the program can be installed on the computer. Here, the recording medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a CD-ROM (compact disc read only memory), a DVD-ROM (digital versatile disc read only memory), a USB memory, or the like. In addition, the program may be in a form that is downloaded from an external device via the network 30.

[0033] Next, the operation of the information processing device 20 according to the present embodiment will be described with reference to Fig. 2 to Fig. 4B. The operation of the information processing device 20 corresponds to an information processing method according to the present embodiment. Fig. 4A and Fig. 4B show an example of the operation of the information processing device 20.

[0034] In step S1, the control unit 21 acquires height information indicating the height h of the antenna 10. Any method may be adopted for acquiring the height information. For example, the control unit 21 may communicate with a server of any organization that manages or operates an electronic reference point, and acquire the height information by receiving the height information stored in the server. The control unit 21 may also acquire the height information by reading the height information pre-stored in the storage unit 22.

[0035] In step S2, the control unit 21 acquires signal information indicating the SNR of the received signal including the satellite signal S1 received by the antenna 10 and the reflected signal S2 generated by the reflection of the satellite signal S1 in the soil of the land where the antenna 10 is installed. The control unit 21 may directly receive and acquire the signal information from the antenna 10, or may acquire the signal information by receiving the signal information transmitted by the antenna 10 to any organization from that organization. The signal information is information generated for each frequency band of the microwave received by the antenna 10 from each of a plurality of satellites including the satellite G1, and for each of the ascending pattern in which each satellite ascends and the descending pattern in which each satellite descends while the elevation angle E of each satellite changes from a predetermined angle to another predetermined angle. The range of change is, for example, 5° < E < 25°. The frequency bands include the L1 band and the L2 band. Hereinafter, the signal information generated for each of the ascending pattern or the descending pattern is referred to as an SNR dataset. Table 1 below shows an example of the signal information in tabular form. The data format of the signal information is not limited to the tabular form. Referring to Table 1, an SNR dataset No. is assigned to each of the ascending pattern and the descending pattern of each satellite.

[0036]

Table 1

[0037] In step S3, the control unit 21 uses a low-order polynomial to remove the trend of the direct wave component. At this time, if the unit of the SNR indicated by the acquired signal information is decibels, the control unit 21 converts it to volts. The low-order polynomial is, for example, a second-order polynomial. This makes it possible to remove the effect of the direct wave component of the received signal becoming stronger as the elevation angle of the satellite position increases.

[0038] In step S4, the control unit 21 obtains the frequency f at which the intensity is the highest for each SNR data set using the LSP. LSP is an abbreviation for Lomb-Scargle Periodogram. The control unit 21 substitutes the obtained frequency f and the wavelength λ of the frequency band L1 or L2 related to the SNR data set into Equation 6 described below. In this manner, the control unit 21 calculates the vertical distance H described below. The control unit 21 stores information indicating the calculated vertical distance H in the storage unit 22. In this embodiment, the wavelength λ of the frequency band L1 is 19.0 cm, and the wavelength λ of the frequency band L2 is 24.4 cm.

[0039] Each value will be described with reference to FIG. 2. The satellite signal S1 transmitted from the satellite G1 is directly received by the antenna 10. The satellite signal S1 is also reflected by a reflecting surface R in the ground to generate a reflected signal S2, and the antenna 10 receives the reflected signal S2. The vertical distance H is the distance between the phase center point C of the antenna 10 and the reflecting surface R corresponding to the reflected signal S2. In this embodiment, compared to FIG. 5 relating to the conventional technology, it is possible to calculate the moisture content θ of the soil by assuming that the reflection of the satellite signal S1 occurs in the soil rather than on the ground surface. That is, in this embodiment, the relationship between the multipath wave of the SNR and each parameter is expressed by the following formula 2 using the vertical distance H instead of the antenna height h in formula 1 relating to the conventional technology. The relationship between each parameter can also be expressed as formula 3.

[0040]

number

[0041]

number

[0042] In formula 3, n a is the refractive index in air, n s indicates the refractive index in the soil containing water. Also, the refractive index of the soil, n s is expressed as Equation 4.

[0043]

number

[0044] In Equation 4, μ S is the relative permeability, ε S is the relative dielectric constant. In general, in soil moisture measurement using TDR, the relative permeability μ s ≒1, and the relative dielectric constant ε S is approximated by the value of only the real part of the complex dielectric constant. Details of the value are described in, for example, Reference 2 below, so a detailed explanation is omitted. [Reference 2]Topp, GC, Davis, JL, & Annan, AP (1980). Electromagnetic determination of soil water content: Measurements in coaxial transmission lines. Water Resources Research, 16, 574-582

[0045] Furthermore, the refractive index of air, n a ≒ 1. Using the above approximation, we substitute Equation 4 into Equation 3 and rearrange the equation to obtain the relative dielectric constant of soil, ε S is expressed by the following formula 5. The control unit 21 stores information indicating the following formula 5 in the storage unit 22.

[0046]

number

[0047] The control unit 21 reads out information indicating the following formula 6 from the storage unit 22, and as described above, substitutes the acquired frequency f and the wavelength λ of the frequency band L1 or L2 related to the SNR data set into formula 6. The control unit 21 calculates the vertical distance H from formula 6 and stores it in the storage unit 22.

[0048]

number

[0049] In step S5, the control unit 21 calculates the difference (Hh) between the vertical distance H and the height h of the antenna 10, and stores it in the memory unit 22. The control unit 21 stores the value of the difference (Hh) in the memory unit 22 for each SNR data set during a predetermined measurement period. The predetermined measurement period is, for example, two weeks or one month. Table 2 below shows the vertical distance H calculated by the control unit 21 and the difference (Hh) between the vertical distance H and the height h of the antenna 10 for each SNR data set of the signal information in Table 1 above.

[0050] [Table 2]

[0051] In step S6, the control unit 21 calculates the average value of the difference (Hh) during the measurement period for each SNR data set, and stores the average value in the storage unit 22.

[0052] In step S7, the control unit 21 compares the average values ​​of the SNR data sets and selects the frequency band L1 or L2, whichever has the larger average value. For example, when the signal information in Table 2 is acquired over a one-month measurement period, it is assumed that the average value of the difference (Hh) is larger in frequency band L1 than in frequency band L2 for SNR data set No. 1. In this case, the control unit 21 selects frequency band L1 as the frequency band for SNR data set No. 1 for the measurement period.

[0053] In step S8, the control unit 21 selects a relationship corresponding to the selected frequency band from among the relationships between the imaginary part ε″ of the relative dielectric constant of the soil and the water content θ that are stored in advance in the storage unit 22. In this embodiment, the control unit 21 selects the following Equation 7 when the L1 frequency is selected, and selects the following Equation 8 when the L2 frequency is selected.

[0054]

number

[0055]

number

[0056] In step S9, the control unit 21 uses the selected relationship to estimate the penetration depth h' of the satellite signal S1 into the soil before the reflected signal S2 is generated. In this embodiment, the selected formula 7 or 8 is substituted into ε" in the following formula 9 to obtain the theoretical value h' on the left side of the following formula 9. t is calculated as an estimate of the penetration depth h'.

[0057]

number

[0058] The formula for estimating the penetration depth h' is not limited to this, and the control unit 21 substitutes the selected formula 7 or 8 into ε" of formula 9 to obtain h' t Calculate the calculated h' t The penetration depth h' may be estimated using Equation 10 below. Equation 10 is an example of an equation for correcting the estimated value of the penetration depth h' using the average value of the difference between the vertical distance H and the height h of the antenna 10. Using Equation 10, the control unit 21 can estimate the penetration depth h'. The equation for correction is not limited to Equation 10, and may be set arbitrarily.

[0059]

number

[0060] In step S10, the control unit 21 substitutes the estimated penetration depth h' and the difference between the vertical distance H and the height h of the antenna 10 indicated by the height information into the right side of the above formula 5. As a result, the control unit 21 calculates the relative dielectric constant ε S and the soil moisture content θ on the right-hand side is derived.

[0061] In step S11, the control unit 21 acquires soil texture information indicating the soil texture of the soil. The control unit 21 may acquire the soil texture information by reading out soil texture information previously stored in the storage unit 22, or may acquire the soil texture information by communicating with a server owned by a private or public institution that accumulates soil types from various locations, and receiving soil texture information for the position where the antenna 10 is installed from the server. The control unit 21 calculates the relative dielectric constant ε S The equation expressing the relationship between the relative dielectric constant ε of the soil and the moisture content θ of the soil is read out from the storage unit 22 and acquired. S and the soil moisture content θ is stored in advance in the storage unit 22. The control unit 21 introduces the obtained equation into the left side of the above-mentioned equation 5.

[0062] The control unit 21 may acquire a preset formula when soil texture information is not acquired or when the acquired soil texture is a general soil texture. For example, the control unit 21 may acquire the following formula 11 described in Reference 2 and introduce the formula 11 into the left side of the derived formula 5 above.

[0063]

number

[0064] The above formula 11 is the relative dielectric constant ε of general soil including sand. S This is an equation showing the relationship between the soil moisture content θ and the soil water content θ. Since the explanation is given in Reference 2 mentioned above, a detailed explanation is omitted here.

[0065] In step S12, the control unit 21 derives an equation whose only unknown variable is the soil moisture content θ by applying the calculated values ​​to the right and left sides of the derived equation 5. The above-mentioned equations 5 and 11 are described again below.

[0066]

number

[0067]

number

[0068] In Equation 11, the relative dielectric constant of the soil, ε S is expressed only by the soil moisture content θ. From Equation 5 and Equation 11, the relative dielectric constant of the soil ε S is on the left side, and the right sides of Equation 5 and Equation 11 can be connected with an equal sign, so the difference between the vertical distance H and the height h of the antenna 10 divided by the penetration depth h' and squared is expressed only in terms of the soil moisture content θ.

[0069] In step S13, the control unit 21 obtains the soil moisture content θ by calculating the solution of the derived equation, and stores the obtained value in the storage unit 22. Thereafter, the processing of the control unit 21 ends.

[0070] FIG. 3 is a graph showing the moisture content calculated for soil with dry soil type using a satellite signal of PRN7 and the moisture content calculated for soil with wet soil type using a satellite signal of PRN27. Here, PRN is an abbreviation for pseudo random noise. The combination of PRN and an identification number indicates a number unique to the satellite. The vertical axis of the graph in FIG. 3 indicates the difference (Hh) also shown in the above formula 5, and the horizontal axis indicates the moisture content θ of the soil. From FIG. 3, it can be seen that the moisture content of the wet soil is calculated to be greater than that of the dry soil, and the information processing device 20 can appropriately calculate the moisture content θ of the soil. The calculation results in FIG. 3 are measured with a certain degree of accuracy when compared with the measurement results by a TDR device installed at the site where the antenna 10 used for the calculation is located.

[0071] As described above, the information processing device 20 of this embodiment acquires height information indicating the height h of the antenna 10 receiving the satellite signal transmitted from the satellite, and signal information indicating the SNR of the received signal received by the antenna 10, including the satellite signal and a reflected signal generated when the satellite signal is reflected in the soil of the land on which the antenna 10 is installed, and is equipped with a control unit 21 that estimates the penetration depth h' of the satellite signal that has penetrated into the soil before the reflected signal is generated based on the acquired height information and signal information, and calculates the moisture content θ of the soil using the obtained estimated value of penetration depth h'.

[0072] According to this embodiment, it is assumed that the signal is reflected in the soil, and the moisture content of the soil can be calculated using the estimated penetration depth of the signal into the soil. Since the absolute value of the moisture content of the soil can be calculated using the antenna 10 already present in various places, there is no need to directly insert a sensor into the soil or to measure the initial value of the soil moisture content by sampling the soil, and costs can be reduced. Therefore, it is possible to improve the method of remotely measuring the moisture content of the soil using measurement data by GNSS.

[0073] As described above, in the information processing device 20 of this embodiment, the control unit 21 derives the relationship between the difference between the vertical distance H between the phase center point of the antenna 10 and the reflecting surface corresponding to the reflected signal, which is calculated from the penetration depth h' and the SNR of the received signal indicated in the signal information, and the height h of the antenna 10 indicated in the height information, and the moisture content θ of the soil, and calculates the moisture content θ of the soil by applying the corresponding vertical distance H to the derived relationship each time signal information is acquired.

[0074] According to this embodiment, it is possible to calculate the soil moisture content θ by using the estimated value of the penetration depth as a reference and taking into consideration the difference between the vertical distance H relative to the reference value and the height h of the antenna 10 indicated by the height information. This makes it possible to calculate the soil moisture content θ with higher accuracy.

[0075] As described above, in the information processing device 20 of this embodiment, the control unit 21 acquires, as signal information, information indicating the SNR of multiple received signals received by the antenna 10, including multiple satellite signals having different wavelengths from each other and multiple corresponding reflected signals, selects from the wavelengths of the multiple satellite signals the wavelength that has the largest average value of the difference between the vertical distance H corresponding to the information acquired as signal information during a certain period and the height h of the antenna, and derives a relationship that differs depending on the selected wavelength as the relationship between the difference between the vertical distance H and the height h of the antenna 10 and the moisture content θ of the soil.

[0076] According to this embodiment, the difference between the vertical distance H and the antenna height h can be calculated for each different wavelength for the same satellite. By being able to select the relationship for the wavelength for which the average value of these differences is larger, it is possible to maintain the accuracy of the calculation of the soil moisture content θ even when the number of satellites from which the antenna 10 receives satellite signals is small.

[0077] As described above, in the information processing device 20 of this embodiment, the control unit 21 acquires soil texture information indicating the soil texture of the soil, and derives a relationship that differs depending on the soil texture indicated by the acquired soil texture information as a relationship between the difference between the vertical distance H and the height h of the antenna 10 and the moisture content θ of the soil.

[0078] According to this embodiment, a relational expression between the relative dielectric constant and the water content, which differs depending on the soil texture, is introduced, making it possible to more accurately calculate the water content of any soil.

[0079] As described above, in the information processing device 20 according to this embodiment, the control unit 21 calculates the moisture content θ of the soil after correcting the estimated value using the difference.

[0080] According to this embodiment, by correcting the estimated value using the difference between the vertical distance H and the antenna height h, it is possible to more accurately calculate the soil moisture content θ using a value that corresponds to the soil near each antenna 10.

[0081] The following supplementary notes are further disclosed regarding the above embodiment.

[0082] (Additional note 1) acquiring height information indicating the height of an antenna receiving a satellite signal transmitted from a satellite, and signal information indicating a signal-to-noise ratio of a received signal including the satellite signal and a reflected signal generated by the satellite signal being reflected in the soil of the land on which the antenna is installed, Based on the acquired height information and the signal information, estimate a penetration depth of the satellite signal into the soil before the reflected signal is generated; Calculating the moisture content of the soil using the obtained estimated value of the penetration depth. An information processing device comprising a control unit. (Additional note 2) The information processing device according to claim 1, The control unit is deriving a relationship between the difference between the vertical distance between the phase center point of the antenna and a reflection surface corresponding to the reflected signal, which is calculated from the penetration depth and the signal-to-noise ratio of the received signal indicated by the signal information, and the height of the antenna indicated by the height information, and the moisture content of the soil; The information processing device calculates the moisture content of the soil by applying the corresponding vertical distance to the derived relationship each time the signal information is acquired. (Additional note 3) The information processing device according to claim 2, The control unit is Acquire, as the signal information, information indicating a signal-to-noise ratio of a plurality of received signals including a plurality of satellite signals having different wavelengths and a plurality of corresponding reflected signals received by the antenna; selecting a wavelength from among the wavelengths of the plurality of satellite signals that has a larger average value of the difference between the vertical distance corresponding to information acquired as the signal information during a certain period and the height of the antenna; An information processing device that derives, as the relationship, a relationship that differs depending on a selected wavelength. (Additional note 4) The information processing device according to claim 2 or 3, The control unit is Obtaining soil texture information indicating the soil texture of the soil; An information processing device that derives as the relationship a relationship that differs depending on the soil texture of the soil indicated by the acquired soil texture information. (Additional note 5) The information processing device according to any one of claims 2 to 4, The control unit is The information processing device calculates the moisture content of the soil after correcting the estimated value of the penetration depth using the difference. (Additional note 6) An information processing method executed by an information processing device, Obtaining height information indicating the height of an antenna receiving a satellite signal transmitted from a satellite, and signal information indicating a signal-to-noise ratio of a received signal including the satellite signal and a reflected signal generated by the satellite signal being reflected in the soil of the land on which the antenna is installed, received by the antenna; estimating a penetration depth of the satellite signal into the soil before the reflected signal is generated based on the acquired height information and the signal information; Calculating the moisture content of the soil using the obtained estimated value of the penetration depth. An information processing method comprising: (Additional note 7) The information processing method according to claim 6, Calculating the moisture content of the soil Deriving a relationship between the difference between the vertical distance between the phase center point of the antenna and a reflection surface corresponding to the reflected signal, which is calculated from the penetration depth and the signal-to-noise ratio of the received signal indicated by the signal information, and the height of the antenna indicated by the height information, and the moisture content of the soil; Each time the signal information is acquired, the corresponding vertical distance is applied to the derived relationship to calculate the moisture content of the soil. An information processing method comprising: (Additional note 8) A program for causing a computer to function as the information processing device according to any one of claims 1 to 5.

[0083] Although the present disclosure has been described based on the drawings and embodiments, it should be noted that those skilled in the art can make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these modifications and corrections are included in the scope of the present disclosure. [Explanation of symbols]

[0084] 1 System 10 Antennas 20 Information processing device 21 Control section 22 Memory section 23 Communications Department 24 Input section 25 Output section 30 Network

Claims

1. Acquire height information indicating the height of an antenna receiving a satellite signal transmitted from a satellite, and signal information indicating a signal-to-noise ratio of a received signal including the satellite signal and a reflected signal generated by the satellite signal being reflected in the soil of the land on which the antenna is installed, received by the antenna; Based on the acquired height information and the signal information, estimate a penetration depth of the satellite signal into the soil until the reflected signal is generated; Calculating the moisture content of the soil using the obtained estimated value of the penetration depth. An information processing device comprising a control unit.

2. 2. The information processing device according to claim 1, The control unit is deriving a relationship between the difference between the vertical distance between the phase center point of the antenna and a reflection surface corresponding to the reflected signal, which is calculated from the penetration depth and the signal-to-noise ratio of the received signal indicated by the signal information, and the height of the antenna indicated by the height information, and the moisture content of the soil; The information processing device calculates the moisture content of the soil by applying the corresponding vertical distance to the derived relationship each time the signal information is acquired.

3. 3. The information processing device according to claim 2, The control unit is Acquire, as the signal information, information indicating a signal-to-noise ratio of a plurality of received signals including a plurality of satellite signals having different wavelengths and a plurality of corresponding reflected signals received by the antenna; selecting a wavelength from among the wavelengths of the plurality of satellite signals that has a larger average value of the difference between the vertical distance corresponding to information acquired as the signal information during a certain period and the height of the antenna; An information processing device that derives, as the relationship, a relationship that differs depending on a selected wavelength.

4. 3. The information processing device according to claim 2, The control unit is Obtaining soil texture information indicating the soil texture of the soil; An information processing device that derives as the relationship a relationship that differs depending on the soil texture of the soil indicated by the acquired soil texture information.

5. 3. The information processing device according to claim 2, The control unit is The information processing device calculates the moisture content of the soil after correcting the estimated value of the penetration depth using the difference.

6. An information processing method executed by an information processing device, Obtaining height information indicating the height of an antenna receiving a satellite signal transmitted from a satellite, and signal information indicating a signal-to-noise ratio of a received signal including the satellite signal and a reflected signal generated by the satellite signal being reflected in the soil of the land on which the antenna is installed, received by the antenna; estimating a penetration depth of the satellite signal into the soil before the reflected signal is generated based on the acquired height information and the signal information; Calculating the moisture content of the soil using the obtained estimated value of the penetration depth. An information processing method comprising:

7. 7. An information processing method according to claim 6, Calculating the moisture content of the soil Deriving a relationship between the difference between the vertical distance between the phase center point of the antenna and a reflection surface corresponding to the reflected signal, which is calculated from the penetration depth and the signal-to-noise ratio of the received signal indicated by the signal information, and the height of the antenna indicated by the height information, and the moisture content of the soil; Each time the signal information is acquired, the corresponding vertical distance is applied to the derived relationship to calculate the moisture content of the soil. An information processing method comprising:

8. A program for causing a computer to function as the information processing device according to any one of claims 1 to 5.

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