Control device, control method, control system, and program

Abstract

To easily calculate a regression equation for measuring soil moisture content.SOLUTION: A control device according to the present disclosure includes: an input unit 31 for accepting input of water level information indicating a water level d of water housed in a water tank; a reception wave information acquisition unit 32 for acquiring reception wave information indicating a reception wave based on a direct wave Pd of an electromagnetic wave transmitted from a satellite and received by a receiver and a reflected wave Pr reflected by the electromagnetic wave on the water surface; a phase calculation unit 33 for calculating a phase φ in the sine function when the signal-to-noise ratio of the signal indicating the reception wave is fitted to a sine function using the satellite elevation angle as a variable; and a regression equation calculation unit 34 for calculating a regression equation indicating the relation between the water level and the phase.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control device, a control method, a control system, and a program. [Background technology]

[0002] Soil moisture content has been measured for purposes such as predicting landslides, managing agricultural land, and forecasting weather. The TDR method using a contact sensor has been used to measure soil moisture content. While this method can measure soil moisture content with high accuracy, its measurement range is limited to a small area of ​​a few centimeters.

[0003] In recent years, technology has been developed to measure soil moisture using electromagnetic waves transmitted from satellites of the Global Navigation Satellite System (GNSS) and propagating in multiple paths. Specifically, the phase of the signal-to-noise ratio (SNR) of electromagnetic waves, which are based on the direct wave of the electromagnetic wave transmitted from the satellite and the wave reflected by the ground and received by a GNSS receiver, depends on the soil moisture. Therefore, soil moisture is measured based on the phase of the SNR (see Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Larson, KM, et 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(1): 91-99. Summary of the Invention [Problem to be solved by the invention]

[0005] However, the regression equation showing the relationship between the phase of the signal-to-noise ratio and the soil moisture content must be calculated in advance. Therefore, it is necessary to calculate the SNR of the received electromagnetic waves in advance and measure the soil moisture content at the time the electromagnetic waves are received using a soil moisture meter multiple times. Furthermore, since the area of ​​soil whose moisture is measured in one measurement by a soil moisture meter is smaller than the entire area of ​​soil that is the target of measurement in actual operation, in order to calculate the regression equation that applies to the entire area of ​​the soil, it is necessary to install multiple soil moisture meters in a wide area, which increases the load.

[0006] Furthermore, the regression equation showing the relationship between the phase of the signal-to-noise ratio and soil moisture content depends on conditions including the satellite transmitting the electromagnetic waves, the frequency of the electromagnetic waves, the receiver receiving the electromagnetic waves, the antenna installed on the receiver, and the height of the receiver from the ground. Therefore, in order to calculate the relationship between the phase and soil moisture content for each condition, soil moisture content must be measured using a soil moisture meter for each condition, which is a heavy burden. Furthermore, if soil moisture content is measured using the regression equation in an environment where the conditions are not suitable, the measurement accuracy will be low.

[0007] In view of the above circumstances, an object of the present disclosure is to provide a control device, a control method, a control system, and a program that can easily calculate a regression equation for measuring soil moisture content. [Means for solving the problem]

[0008] In order to solve the above problem, the control device according to the present disclosure includes an input unit that accepts input of water level information indicating the water level of water contained in a tank; a received wave information acquisition unit that acquires received wave information indicating received waves based on direct electromagnetic waves transmitted from a satellite and received by a receiver and reflected waves of the electromagnetic waves reflected on the surface of the water; a phase calculation unit that calculates the phase of a sine function when the signal-to-noise ratio of a signal indicating the received waves is fitted to a sine function with the satellite elevation angle as a variable; and a regression equation calculation unit that calculates a regression equation indicating the relationship between the water level and the phase.

[0009] In order to solve the above problem, the control method of the present disclosure is a control method executed by a control device, and includes the steps of: accepting input of water level information indicating the water level of water contained in a tank; acquiring received wave information indicating received waves based on direct electromagnetic waves transmitted from a satellite and received by a receiver and reflected waves of the electromagnetic waves reflected on the surface of the water; calculating the phase of a sine function when the signal-to-noise ratio of the signal indicating the received waves is fitted to the sine function with the satellite elevation angle as a variable; and calculating a regression equation indicating the relationship between the water level and the phase.

[0010] In order to solve the above problem, the control method according to the present disclosure includes a step of supplying water to a water tank containing soil until the soil is saturated with water; a measuring step of measuring a soil moisture content, which is the amount of water contained in the soil; an acquiring step of acquiring received wave information indicating a received wave when the soil moisture content is measured, based on a direct wave of an electromagnetic wave transmitted from a satellite and received by a receiver and a wave reflected by the surface of the soil from the electromagnetic wave; a phase calculating step of calculating a phase of a sine function when a signal-to-noise ratio of a signal indicating the received wave is fitted to the sine function with a satellite elevation angle as a variable; and a correlation between the soil moisture content and the phase. The method includes a regression equation calculation step of calculating a regression equation that indicates the relationship; a first determination step of determining whether the regression equation has been calculated a predetermined number of times or more; and a second determination step of determining whether the soil moisture content is less than a predetermined soil moisture content threshold if it is determined that the regression equation has not been calculated a predetermined number of times or more, and if it is determined that the soil moisture content is equal to or greater than the predetermined soil moisture content threshold, the measurement step, the acquisition step, the phase calculation step, and the regression equation calculation step are repeated in order until it is determined that the regression equation has been calculated a predetermined number of times or more or it is determined that the soil moisture content is less than the predetermined soil moisture content.

[0011] In order to solve the above problem, the control system according to the present disclosure includes a receiver that receives electromagnetic waves transmitted from a satellite, and a control device, wherein the control device has an input unit that accepts input of water level information indicating the water level of water contained in a tank, a received wave information acquisition unit that acquires received wave information indicating received waves based on direct waves of electromagnetic waves transmitted from the satellite and received by the receiver and reflected waves of the electromagnetic waves reflected on the surface of the water, a phase calculation unit that calculates the phase of a sine function when the signal-to-noise ratio of a signal indicating the received waves is fitted to the sine function with the satellite elevation angle as a variable, and a regression equation calculation unit that calculates a regression equation indicating the relationship between the water level and the phase.

[0012] In order to solve the above problem, a program according to the present disclosure causes a computer to operate as the above-described control device. [Effects of the Invention]

[0013] According to the control device, control method, control system, and program disclosed herein, a regression equation for measuring soil moisture content can be easily calculated. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a control system according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an example of the placement of receivers shown in FIG. [Figure 3] 3 is a graph showing an example of the relationship between the water level of the water tank shown in FIG. 2 and the phase of the signal-to-noise ratio of the received wave received by the receiver. [Figure 4A] 1. FIG. 4 is a schematic diagram showing another example of the arrangement of receivers shown in FIG. [Figure 4B] 1. FIG. 4 is a schematic diagram showing yet another example of the placement of receivers shown in FIG. [Figure 5] 2 is a schematic diagram showing an example of a measurement device that measures soil moisture content using a regression equation calculated by the control system shown in FIG. 1. FIG. [Figure 6] 2 is a flowchart showing the operation of the control device shown in FIG. [Figure 7] 6 is a flowchart showing the operation of the measurement device shown in FIG. 5. [Figure 8] FIG. 10 is a schematic diagram illustrating an example of a control system according to a second embodiment. [Figure 9] FIG. 9 is a schematic diagram showing an example of the placement of receivers shown in FIG. 8. [Figure 10] 9 is a flowchart showing the operation of the control device shown in FIG. 8. [Figure 11] FIG. 10 is a schematic diagram illustrating an example of a control system according to a third embodiment. [Figure 12] FIG. 12 is a schematic diagram showing an example of the placement of receivers shown in FIG. [Figure 13] FIG. 13 is an example of a top view of the water tank shown in FIG. 12. [Figure 14] 12 is a flowchart showing the operation of the control device shown in FIG. [Figure 15] FIG. 10 is a schematic diagram illustrating an example of a control system according to a fourth embodiment. [Figure 16] 13 is another example of a top view of the water tank shown in FIG. 12. [Figure 17] 16 is a flowchart showing the operation of the control device shown in FIG. 15. [Figure 18] FIG. 10 is a schematic diagram illustrating an example of a circulation system provided in a modified example of the control system. [Figure 19] 2 is a diagram illustrating an example of a hardware configuration of a control device illustrated in FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] <<First embodiment>> The overall configuration of the first embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing an example of a control system 100 according to the first embodiment.

[0016] As shown in FIG. 1, the control system 100 includes a water level meter 1, a receiver 2, and a control device 3.

[0017] The water level meter 1 measures the water level d of the water W contained in the water tank AQ as shown in Fig. 2. The water level meter 1 can measure the water level d by any method.

[0018] The receiver 2 receives GNSS signals transmitted from GNSS satellites ST. The receiver 2 may be a GNSS receiver equipped with a GNSS antenna. In the first embodiment, the receiver 2 is disposed at a position higher than the maximum water level d of the water W contained in the water tank AQ. In the example shown in FIG. 2, an installation stand IS is disposed in the water tank AQ, and the receiver 2 is disposed on the installation stand IS.

[0019] <Control device configuration> 1, the control device 3 includes an input unit (first input unit) 31, a received wave information acquisition unit (first received wave information acquisition unit) 32, a phase calculation unit 33, a regression equation calculation unit 34, a determination unit 35, and an output unit (first output unit) 36. The control device 3 may be configured integrally with the receiver 2.

[0020] The input unit 31 is configured with an input interface. The input interface may be a mouse, a keyboard, or the like, or may be a communication interface. The communication interface may use standards such as Ethernet (registered trademark), FDDI (Fiber Distributed Data Interface), or Wi-Fi (registered trademark). The received wave information acquisition unit 32, the phase calculation unit 33, the regression equation calculation unit 34, and the determination unit 35 are configured with a controller. The controller may be configured with dedicated hardware such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array), or may be configured with a processor, or may be configured with both. The output unit 36 ​​is configured with an output interface. The output interface may be a display such as an organic EL (Electro Luminescence) panel or a liquid crystal panel, or may be a communication interface.

[0021] The input unit 31 accepts input of water level information indicating the water level d of the water W contained in the water tank AQ. The water level d may be measured by the water level meter 1 as described above. Note that the control system 100 does not need to be equipped with the water level meter 1, and with this configuration, the input unit 31 accepts input of water level information indicating the water level d measured by any water level meter not included in the control system 100.

[0022] The input unit 31 also accepts input of condition information indicating conditions related to reception of electromagnetic waves from a satellite ST by the receiver 2. The condition information may include, for example, information indicating the satellite ST, the frequency or wavelength of the electromagnetic waves, the receiver 2, the antenna, and the antenna height H. The information indicating the satellite ST may be information for identifying the satellite ST or information for identifying the type of satellite ST. The same applies to the information indicating the receiver 2 and the antenna. The antenna height H is the height of the antenna from the bottom of the aquarium AQ.

[0023] The received wave information acquisition unit 32 acquires received wave information indicating received waves transmitted from the satellite ST and received by the receiver 2. As shown in Fig. 2, the received waves are electromagnetic waves based on direct waves Pd of the electromagnetic waves transmitted from the satellite ST and reflected waves Pr of the electromagnetic waves transmitted from the satellite ST reflected on the surface of the water W. Specifically, the received waves are interference waves formed by interference between the direct waves Pd and the reflected waves Pr.

[0024] 1, the phase calculation unit 33 calculates the phase φ of a sine function when the signal-to-noise ratio of the signal indicating the received wave included in the received wave information is fitted to the sine function with the satellite elevation angle E as a variable. The satellite elevation angle E is the acute angle formed between the traveling direction of the electromagnetic wave transmitted from the GNSS satellite ST and the surface of the water W contained in the water tank AQ, onto which the electromagnetic wave is incident.

[0025] Specifically, the phase calculation unit 33 calculates the signal-to-noise ratio of the received wave indicated by the received wave information acquired by the received wave information acquisition unit 32. Then, the phase calculation unit 33 extracts the signal-to-noise ratio within a predetermined range of satellite elevation angle E (for example, 5° or more and 20° or less). Furthermore, the phase calculation unit 33 removes the trend of the signal-to-noise ratio and calculates the phase φ by fitting it to a sine function with satellite elevation angle E as a variable, as shown in the following equation (1). Note that in equation (1), A, h, and λ are the amplitude of the sine wave indicated by the sine function, the height of the antenna from the water surface, and the wavelength of the received wave, respectively.

number

[0026] The regression equation calculation unit 34 calculates a regression equation that indicates the relationship between the water level d and the phase φ. Specifically, the regression equation calculation unit 34 calculates a regression equation (an equation that indicates a regression line that is represented by a straight line in the example of FIG. 3) that indicates the relationship between the water level d input by the input unit 31 and the phase φ calculated by the phase calculation unit 33, as shown in FIG. 3. The regression equation calculation unit 34 can calculate the regression equation by known regression analysis.

[0027] When the regression equation is calculated by the regression equation calculation unit 34, the determination unit 35 determines whether the regression equation has been calculated a predetermined number of times or more. When it is determined that the regression equation has been calculated a predetermined number of times or more, the determination unit 35 causes the output unit 36 ​​to output regression equation information including the regression equation most recently calculated by the regression equation calculation unit 34.

[0028] The regression equation information includes the regression equation calculated by the regression equation calculation unit 34. The regression equation information may further include, in addition to the regression equation, condition information corresponding to the regression equation. The condition information corresponding to the regression equation is condition information related to the received wave included in the received wave information used to calculate the regression equation. For example, if an electromagnetic wave with a frequency "L1" is received from a satellite ST identified by "GPS No. 1" by an antenna of a "choke ring" of a receiver 2 identified by "Company A, Product Name x" and a regression equation is calculated, the determination unit 35 causes the output unit 36 ​​to output the regression equation information including the condition information indicating the conditions of the satellite ST "GPS No. 1," the frequency "L1," the receiver 2 "Company A, Product Name x," and the antenna "choke ring," along with the regression equation.

[0029] Furthermore, when it is determined that the regression equation has not been calculated a predetermined number of times or more, the determination unit 35 determines whether the water level d is less than a predetermined water level threshold. The predetermined water level threshold can be, for example, the depth a of the aquarium AQ. When it is determined that the water level d is equal to or greater than the predetermined water level threshold (when the predetermined water level threshold is the depth a of the aquarium AQ, the water level d is equal to the predetermined water level threshold), the determination unit 35 causes the output unit 36 ​​to output regression equation information including the regression equation most recently calculated by the regression equation calculation unit 34.

[0030] When the determination unit 35 determines that the water level d is below a predetermined water level threshold, it outputs a command to change the water level d to the output unit 36. When the water level d changes as water is supplied to or drained from the water tank AQ based on the command output by the output unit 36, the determination unit 35 can execute the above-mentioned process again based on information indicating the water level d measured again by the water level meter and received wave information regarding the received waves received by the receiver 2.

[0031] The output unit 36 ​​outputs the regression equation information under the control of the determination unit 35. The output unit 36 ​​may display the regression equation information on a display device such as an organic EL (Electro Luminescence) or liquid crystal panel, or may transmit the regression equation information to another device via a communication network.

[0032] Furthermore, the output unit 36 ​​outputs a command to change the water level d under the control of the determination unit 35. The output unit 36 ​​may output the command to a water supply and drainage control device that controls the water supply and drainage equipment, or may cause a display device to display the command.

[0033] As shown in FIG. 4A, the control system 100 may include multiple receivers 2 installed at different antenna heights Hk (k is a natural number, and in the example shown in FIG. 4A, k = 1 to 3). In this configuration, the input unit 31 receives input of condition information indicating conditions including the receiver 2, the satellite ST, the frequency or wavelength of the electromagnetic waves from the satellite ST, the antenna, and the antenna height Hk. The regression equation calculation unit 34 then calculates a regression equation based on received wave information including the received waves received by each of the multiple receivers 2, and the output unit 36 ​​outputs regression equation information including each regression equation and its corresponding condition information. In this way, the control device 3 can calculate a regression equation for each of different conditions, including different antenna heights Hk. Therefore, even when the antenna heights Hk of the receivers 2 vary, soil moisture content can be calculated with high accuracy by using a regression equation that matches the conditions from among the regression equations calculated by the control device 3.

[0034] 4B, the receiver 2 may be provided so as to be movable in the vertical direction. In such a configuration, the input unit 31 receives input of condition information indicating conditions including the antenna height H when the receiver 2 is positioned at each of different antenna heights H. The regression equation calculation unit 34 then calculates a regression equation based on received wave information including received waves received by each of the multiple receivers 2, and the output unit 36 ​​outputs regression equation information including each regression equation and its corresponding condition. In this manner, the control device 3 can calculate a regression equation for each of different conditions, including different antenna heights H. Therefore, even when the antenna height H of the receiver 2 varies, soil moisture content can be calculated with high accuracy by using one of the regression equations calculated by the control device 3 that matches the conditions.

[0035] <Configuration of measurement equipment> Here, referring to Fig. 5, a description will be given of a measurement device 4 that measures soil moisture content using a regression equation calculated by the control device 3. Fig. 5 is a schematic diagram showing an example of the measurement device 4 according to the first embodiment.

[0036] As shown in FIG. 5, the measurement device 4 includes an input unit (second input unit) 41, a received wave information acquisition unit (second received wave information acquisition unit) 42, a regression equation storage unit 43, a soil moisture content measurement unit 44, and an output unit (second output unit) 45. The input unit 41 is configured by an input interface. The received wave information acquisition unit 42 and the soil moisture content measurement unit 44 are configured by a controller. The regression equation storage unit 43 is configured by a memory. The memory may be configured by a register in hardware such as an ASIC or FPGA, or may be configured by a hard disk drive (HDD), a solid state drive (SSD), an electrically erasable programmable read-only memory (EEPROM), a read-only memory (ROM), a random access memory (RAM), or the like. The output unit 45 is configured by an output interface.

[0037] The input unit 41 can receive input of condition information. The condition information may include conditions such as the satellite ST, the receiver 2, the frequency or wavelength of the electromagnetic waves transmitted from the satellite ST, the antenna, and the height of the antenna from the ground.

[0038] The received wave information acquisition unit 42 acquires received wave information indicating received waves based on direct electromagnetic waves Pd transmitted from the satellite ST and received by the receiver 2 and reflected waves Pr reflected from the surface of the soil.

[0039] The regression equation storage unit 43 stores the regression equation calculated by the above-mentioned control device 3. The regression equation storage unit 43 can store the regression equation in correspondence with the condition information.

[0040] The soil moisture amount measuring unit 44 measures the soil moisture amount based on the received wave information acquired by the received wave information acquiring unit 42 and the regression equation stored in the regression equation storage unit 43. The soil moisture amount measuring unit 44 may measure the soil moisture amount based on the condition information input by the input unit 41, the received wave information, and the regression equation corresponding to the condition information.

[0041] Specifically, the soil moisture measurement unit 44 calculates the phase φ of a sine function obtained by fitting the signal-to-noise ratio of a signal indicating the received wave included in the received wave information to a sine function with the satellite elevation angle E as a variable.The soil moisture measurement unit 44 then measures the soil moisture based on the phase φ and a regression equation.Specifically, the soil moisture measurement unit 44 calculates a water level d corresponding to the phase φ in the regression equation stored in the regression equation storage unit 43, and measures the amount equivalent to the water level d as the soil moisture amount.

[0042] As described above, in a configuration in which the input unit 41 accepts input of condition information and the regression equation storage unit 43 stores a regression equation corresponding to the condition information, the soil moisture amount measurement unit 44 calculates the water level d corresponding to the phase φ in the regression equation stored corresponding to the condition information, and measures the amount equivalent to the water level d as the soil moisture amount. Note that in a configuration in which the condition information includes the antenna height from the ground, the soil moisture amount measurement unit 44 measures the soil moisture amount using the regression equation associated with the antenna height H, which corresponds to the antenna height from the ground.

[0043] Furthermore, the output unit 45 may output soil moisture content information indicating the soil moisture content measured by the soil moisture content measuring unit 44. For example, the output unit 45 may display the soil moisture content information on a display device, or may transmit the soil moisture content information to another device via a communication network.

[0044] <Control device operation> Here, an operation using the control device 3 according to the first embodiment will be described with reference to Fig. 6. Fig. 6 is a flowchart showing an example of an operation using the control device 3 according to the first embodiment. The operation using the control device 3 described with reference to Fig. 6 includes a control method executed by the control device 3 according to the first embodiment.

[0045] In step S11, the water supply equipment supplies water W to the aquarium AQ. Here, a water supply and drainage control device (not shown) may control the water supply equipment to supply water W to the aquarium AQ, or an administrator may operate the water supply equipment to supply water W to the aquarium AQ.

[0046] In step S12, the water level meter 1 measures the water level d.

[0047] In step S13, water level information indicating the water level d measured in step S12 is input to the control device 3. As a result, the input unit 31 accepts the input of water level information indicating the water level d of the water W contained in the water tank AQ.

[0048] In step S14, the received wave information acquisition unit 32 acquires received wave information indicating the received wave based on the direct electromagnetic wave Pd transmitted from the satellite ST and received by the receiver 2 and the reflected wave Pr of the electromagnetic wave reflected on the surface of the water W.

[0049] In step S15, the phase calculation unit 33 calculates the phase φ in a sine function when the signal-to-noise ratio of the signal indicating the received wave included in the received wave information is fitted to the sine function with the satellite elevation angle E as a variable.

[0050] In step S16, the regression equation calculation unit 34 calculates a regression equation that indicates the relationship between the water level d and the phase φ.

[0051] In step S17, the determination unit 35 determines whether or not the regression equation has been calculated a predetermined number of times or more.

[0052] If it is determined in step S17 that the regression equation has been calculated a predetermined number of times or more, then in step S18, the determination unit 35 causes the output unit 36 ​​to output regression equation information including the regression equation last calculated in step S16.

[0053] If it is determined in step S17 that the regression equation has not been calculated the predetermined number of times or more, then in step S19, the determination unit 35 determines whether or not the water level d is less than a predetermined water level threshold value.

[0054] If it is determined in step S19 that the water level d is equal to or greater than a predetermined water level threshold (if the predetermined water level threshold is the depth a of the aquarium AQ, the water level d is equal to the predetermined water level threshold), then in step S18, the determination unit 35 causes the output unit 36 ​​to output regression equation information including the regression equation finally calculated in step S16.

[0055] If it is determined in step S19 that the water level d is less than the predetermined water level threshold, the determination unit 35 causes the output unit 36 ​​to output a command to change the water level d, and the process returns to step S11 and is repeated.

[0056] In step S11 described above, the water supply equipment supplies water W to the water tank AQ, but this is not limiting. For example, operation may be started from an initial state in which the water tank AQ is filled with water W, and then in step S11, the drainage equipment may drain the water W from the water tank AQ. Furthermore, the determination unit 35 may send a command to the water supply and drainage control device to supply or drain the water W, or an administrator may operate the water supply or drainage equipment by referring to the result of the determination by the determination unit 35.

[0057] Next, the operation of the measurement device 4 according to the first embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing an example of the operation of the measurement device 4 according to the first embodiment. The operation of the measurement device 4 described with reference to Fig. 7 corresponds to the measurement method executed by the measurement device 4 according to the first embodiment. The regression equation storage unit 43 of the measurement device 4 stores the regression equation information output by the control device 3 described above.

[0058] In step S21, the received wave information acquisition unit 42 acquires received wave information indicating received waves based on the direct wave Pd and the reflected wave Pr received by the receiver 2.

[0059] In step S22, the soil moisture content measurement unit 44 calculates the phase φ of the sine function when the signal-to-noise ratio of the signal indicating the received wave included in the received wave information is fitted to the sine function with the satellite elevation angle E as a variable, and measures the soil moisture content from the water level d calculated using a regression equation based on the phase φ.

[0060] In step S23, the output unit 45 outputs soil moisture information indicating the soil moisture content.

[0061] As described above, according to the first embodiment, the control device 3 includes an input unit 31 that accepts input of water level information indicating the water level d of the water W contained in the water tank AQ; a received wave information acquisition unit 32 that acquires received wave information indicating received waves based on direct electromagnetic waves Pd and reflected waves Pr of the electromagnetic waves reflected by the surface of the water W, both transmitted from the satellite ST and received by the receiver 2; a phase calculation unit 33 that calculates the phase φ of a sine function when the signal-to-noise ratio of the signal indicating the received waves is fitted to the sine function with the satellite elevation angle E as a variable; and a regression equation calculation unit 34 that calculates a regression equation indicating the relationship between the water level d and the phase φ. This allows the control device 3 to easily calculate the regression equation indicating the relationship between the phase φ and the soil moisture content. Specifically, compared to conventional methods of measuring soil moisture content using soil moisture meters installed throughout the entire area of ​​the soil to be measured, it is easier to set the water level d of the water W contained in the water tank AQ to a desired value. Therefore, setting the water level d to various values ​​and calculating a regression equation showing the relationship between the water level d and the phase φ of the received wave at each of these settings is easier than calculating a regression equation showing the relationship between the soil moisture content measured by a soil moisture meter and the phase φ of the received wave.

[0062] Furthermore, according to the first embodiment, the control device 3 further includes an output unit 36 ​​that receives input of condition information indicating conditions related to reception of electromagnetic waves from the satellite ST by the receiver 2 and outputs regression equation information including a regression equation and condition information corresponding to the regression equation. This allows the control device 3 to easily calculate a regression equation for measuring soil moisture content for each condition. Therefore, by using a regression equation for each condition, it becomes possible to measure soil moisture content with high accuracy.

[0063] <<Second embodiment>> The overall configuration of the second embodiment will be described with reference to Fig. 8. Fig. 8 is a schematic diagram showing an example of a control system 100-1 according to the second embodiment. In the second embodiment, the same functional units as those in the first embodiment are given the same reference numerals, and descriptions thereof will be omitted. In this embodiment, as shown in Fig. 9, soil SL is contained in a water tank AQ.

[0064] In the second embodiment, it is preferable that the texture of the soil SL contained in the water tank AQ is similar to the texture of the soil to be measured. For example, the difference between the particle size of the soil SL contained in the water tank AQ and the particle size of the soil to be measured can be equal to or less than a threshold value. Furthermore, the difference between the amount of predetermined organic matter contained in the soil SL contained in the water tank AQ and the amount of predetermined organic matter contained in the soil to be measured can be equal to or less than a threshold value. However, this example is not limiting, and the soil SL to be contained in the water tank AQ may be selected based on the soil texture with respect to salts, ions, etc.

[0065] As shown in FIG. 8, the control system 100-1 includes a receiver 2, a control device 3-1, and a soil moisture meter 5.

[0066] The soil moisture meter 5 measures the soil moisture content, which is the amount of water in the soil SL. The soil moisture meter 5 can measure the soil moisture content by any method. For example, the soil moisture meter 5 may measure the soil moisture content by a TDR (Time Domain Reflectometer system) or a TDT (Time Domain Transmissometry), or may measure the soil moisture content based on the electrical resistance value of the soil SL. The soil moisture meter 5 may also measure the soil moisture content by measuring the weight of the soil containing water.

[0067] <Control device configuration> The control device 3-1 includes an input unit 31-1, a received wave information acquisition unit 32, a phase calculation unit 33, a regression equation calculation unit 34-1, a determination unit 35, and an output unit 36. The input unit 31-1 is configured by an input interface. The regression equation calculation unit 34-1 is configured by a controller.

[0068] The input unit 31-1 receives input of soil moisture information indicating the amount of soil moisture measured by the soil moisture meter 5.

[0069] The regression equation calculation unit 34-1 calculates a regression equation that indicates the relationship between the soil moisture content indicated by the soil moisture content information and the phase φ calculated by the phase calculation unit 33. The regression equation calculation unit 34-1 can calculate the regression equation by known regression analysis.

[0070] <Control device operation> Next, a control method using the control device 3-1 according to the second embodiment will be described. Fig. 10 is a flowchart showing an example of an operation performed using the control device 3-1 according to the second embodiment. The operation performed using the control device 3-1 described with reference to Fig. 10 includes the control method according to the second embodiment.

[0071] In step S31, water W is supplied to the water tank AQ containing the soil SL until the soil SL is saturated with water (water supply step).

[0072] In step S32, the soil moisture meter 5 measures the soil moisture content, which is the amount of moisture contained in the soil SL (measurement step).

[0073] In step S33, soil moisture content information indicating the soil moisture content measured in step S32 is input to the control device 3-1. Here, a controller included in the soil moisture meter 5 may output the soil moisture content information to the control device 3-1, or an administrator may perform an operation to input the soil moisture content information measured by the soil moisture meter 5. As a result, the input unit 31-1 accepts the input of the soil moisture content information.

[0074] In step S34, the received wave information acquisition unit 32 acquires received wave information indicating the received wave when the soil moisture content was measured, based on the direct electromagnetic wave Pd transmitted from the satellite ST and received by the receiver 2, and the reflected wave Pr of the electromagnetic wave reflected on the surface of the soil SL (acquisition step).

[0075] In step S35, the phase calculation unit 33 calculates the phase φ in a sine function when the signal-to-noise ratio of the signal indicating the received wave is fitted to the sine function with the satellite elevation angle E as a variable (phase calculation step).

[0076] In step S36, the regression equation calculation unit 34-1 calculates a regression equation that indicates the relationship between the soil moisture content and the phase φ (regression equation calculation step).

[0077] In step S37, the determination unit 35 determines whether or not the regression equation has been calculated a predetermined number of times or more (first determination step).

[0078] If it is determined in step S37 that the regression equation has been calculated a predetermined number of times or more, then in step S38 the output unit 36 ​​outputs the regression equation calculated last in step S16.

[0079] If it is determined in step S37 that the regression equation has not been calculated the predetermined number of times or more, in step S39, the determination unit 35 determines whether the soil moisture content is less than a predetermined soil moisture content threshold value (second determination step).

[0080] If it is determined in step S39 that the soil moisture content is less than the predetermined soil moisture content threshold, then in step S38, the output unit 36 ​​outputs the regression equation information calculated last in step S36.

[0081] If it is determined in step S39 that the soil moisture content is equal to or greater than the predetermined soil moisture content threshold, the process returns to step S32 and is repeated. That is, the control device 3-1 repeats the measurement step, acquisition step, phase calculation step, and regression equation calculation step in this order until it is determined that the regression equation has been calculated a predetermined number of times or more, or until it is determined that the soil moisture content is less than the predetermined soil moisture content.

[0082] Furthermore, the measuring device 4 in the first embodiment may store the regression equation calculated by the control device 3-1 in the second embodiment and measure the soil moisture content using the regression equation.

[0083] As described above, according to the second embodiment, it is possible to efficiently calculate a regression equation showing the relationship between the phase φ and the soil moisture content as the soil SL gradually dries out from a state where the moisture content is saturated.

[0084] <<Third embodiment>> The overall configuration of the third embodiment will be described with reference to Fig. 11. Fig. 11 is a schematic diagram showing an example of a control system 100-2 according to the third embodiment. In the third embodiment, the same functional units as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0085] As shown in FIG. 11, the control system 100-2 includes a water level meter 1, a receiver 2, and a control device 3-2.

[0086] 12, the water tank AQ is composed of a plurality of water tank subunits AQs that contain water W. The length of the horizontal side of the water tank subunits AQs can be equal to or greater than the wavelength (e.g., 20 cm) of the electromagnetic waves transmitted from the satellite ST.

[0087] A plurality of aquarium subunits AQs are installed around the receiver 2. For example, M aquarium subunits AQs may be installed in one direction and L aquarium subunits AQs in a direction perpendicular to the one direction, with the installation stand IS on which the receiver 2 is installed at the center. In the example shown in Fig. 13, seven aquarium subunits AQs are arranged in the x-axis direction and seven in the y-axis direction, with the installation stand IS on which the receiver 2 is installed at the center.

[0088] <Control device configuration> As shown in Fig. 11, the control device 3-2 includes an input unit 31-2, a received wave information acquisition unit 32-2, a phase calculation unit 33, an output unit 36-2, a phase storage unit 37, and a detection range determination unit 38. The input unit 31-2 is configured by an input interface. The output unit 36-2 is configured by an output interface. The phase storage unit 37 is configured by a memory. The received wave information acquisition unit 32-2 and the detection range determination unit 38 are configured by a controller.

[0089] The received wave information acquisition unit 32-2 acquires received wave information each time the water W is drained from some of the aquarium subunits AQs in which the water W was stored.

[0090] The phase memory unit 37 stores the phase φ calculated by the phase calculation unit 33 and water tank subunit information that identifies the water tank subunit AQs that contains the water W when the phase φ is calculated.

[0091] Based on the difference between the two phases φ most recently stored in the phase storage unit 37, the detection range determination unit 38 determines the detection range in which the soil moisture content is detected based on the received wave information.

[0092] Specifically, when phase calculation unit 33 calculates phase φ, detection range determination unit 38 determines whether the difference between the two phases φ most recently stored in phase memory unit 37 is equal to or greater than a predetermined threshold. If it determines that the difference is equal to or greater than the predetermined threshold, detection range determination unit 38 determines that the range formed by the aquarium subunits AQs corresponding to the aquarium subunit information stored in phase memory unit 37 in association with the most recently stored phase φ is the detection range of the soil moisture content. Detection range determination unit 38 outputs detection range information indicating the detection range to output unit 36-2. Furthermore, detection range determination unit 38 may store the detection range information in a storage unit (memory) included in control device 3-2.

[0093] Furthermore, the output unit 36-2 may output detection range information indicating the detection range determined by the detection range determination unit 38. For example, the output unit 36-2 may cause a display device to display the detection range information, or may transmit the detection range information to another device via a communication network.

[0094] When the detection range determination unit 38 determines that the difference is less than a predetermined threshold, it repeats the same processing based on the phase φ calculated based on the received wave information obtained after water W was discharged from some of the aquarium subunits AQs and stored in the phase memory unit 37.

[0095] <Control device operation> Next, an operation using the control device 3-2 according to the third embodiment will be described. Fig. 14 is a flowchart showing an example of an operation using the control device 3-2 according to the third embodiment. The operation of the control device 3-2 described with reference to Fig. 14 includes a control method executed by the control device 3-2 according to the third embodiment.

[0096] In step S41, the water supply equipment supplies water W to all of the aquarium subunits AQs. Here, a water supply and drainage control device (not shown) may control the water supply equipment to supply water W to each aquarium subunit AQs, or an administrator may operate the water supply equipment to supply water W to the aquarium subunits AQs.

[0097] In step S42, the drainage system drains water W from some of the aquarium subunits AQs. The aquarium subunits AQs from which the water W is drained may be a predetermined number of aquarium subunits AQs that are far away from the receiver 2, as shown in FIG. 13 (in the example shown in FIG. 13, water W is drained from aquarium subunits AQs showing a water level of "0.0"). The aquarium subunits AQs from which the water W is drained may also be determined by the distance from the receiver 2 and the position of the satellite based on orbital information. For example, the aquarium subunits AQs from which the water W is drained may be a predetermined number of aquarium subunits AQs that are far away from the aquarium subunits AQs that are located at the reflection position of the reflected wave Pr transmitted from the satellite ST and received by the receiver 2, based on the position of the satellite ST and the position of the antenna of the receiver 2.

[0098] In step S42, a water supply and drainage control device (not shown) may control the drainage equipment to drain water W from each aquarium subunit AQs, or an administrator may operate the drainage equipment to drain water W from the aquarium subunit AQs.

[0099] In step S43, the received wave information acquisition unit 32-2 acquires received wave information indicating the received wave based on the direct electromagnetic wave Pd transmitted from the satellite ST and received by the receiver 2 and the reflected wave Pr reflected from the surface of the water W.

[0100] In step S44, the phase calculation unit 33 calculates the phase φ in a sine function when the signal-to-noise ratio of the signal indicating the received wave included in the received wave information is fitted to the sine function with the satellite elevation angle E as a variable.

[0101] In step S45, the phase memory unit 37 stores the phase φ calculated by the phase calculation unit 33 together with aquarium subunit information that identifies the aquarium subunit AQs in which water W is contained when the phase φ is calculated.

[0102] In step S46, the detection range determination unit 38 determines whether the difference between the two phases φ most recently stored in the phase storage unit 37 is equal to or greater than a predetermined threshold value.

[0103] If it is determined in step S46 that the difference is greater than or equal to a predetermined threshold, in step S47, the detection range determination unit 38 determines that the range formed by the aquarium subunits AQs corresponding to the aquarium subunit information stored in the phase memory unit 37 in correspondence with the phase φ most recently stored is the detection range of the soil moisture content.

[0104] If it is determined in step S46 that the difference is less than the predetermined threshold value, the control device 3-2 returns to step S42 and repeats the process.

[0105] In step S48, the output unit 36-2 outputs the detection range information.

[0106] The control device 3-2 may further include a regression equation calculation unit 34 and a determination unit 35. In such a configuration, when the control device 3-2 determines the detection range information as described above, it may execute the same operation as in the first embodiment using the aquarium subunits AQs that are within the determined detection range.

[0107] As described above, according to the third embodiment, the water tank AQ is composed of multiple water tank subunits AQs that contain water W, and the received wave information acquisition unit 32-2 acquires received wave information each time water W is drained from some of the water tank subunits AQs that contained the water W, and is equipped with a phase memory unit 37 that stores the phase φ calculated by the phase calculation unit 33 and water tank subunit information that identifies the water tank subunit AQs that contained the water W when the phase φ was calculated, and a detection range determination unit 38 that determines the detection range of the soil moisture content based on the difference between the two phases φ most recently stored in the phase memory unit 37.

[0108] The detection range in which soil moisture content can be detected based on the received waves received by the receiver 2 depends on the position of the antenna of the receiver 2 and the satellite ST. The control device 3-2 of the third embodiment is configured as described above, and can therefore appropriately determine the detection range of soil moisture content.

[0109] <<Fourth embodiment>> The overall configuration of the fourth embodiment will be described with reference to Fig. 15. Fig. 15 is a schematic diagram showing an example of a control system 100-3 according to the fourth embodiment. In the fourth embodiment, the same functional units as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0110] As shown in FIG. 15, the control system 100-3 includes a water level meter 1, a receiver 2, and a control device 3-3.

[0111] In the fourth embodiment, as in the third embodiment, the water tank AQ is composed of a plurality of water tank subunits AQs that contain water W, as shown in FIG.

[0112] <Control device configuration> As shown in Fig. 15, the control device 3-3 includes an input unit 31-3, a received wave information acquisition unit 32, a phase calculation unit 33, a regression equation calculation unit 34, a determination unit 35, an output unit 36-3, and a water tank determination unit 39. The input unit 31-3 is configured by an input interface. The output unit 36-3 is configured by an output interface. The water tank determination unit 39 is configured by a controller.

[0113] Based on the position of the satellite ST, the water tank determination unit 39 determines, from among the multiple water tank subunits AQs, the water tank subunit AQs that will contain the water W. The position (planned orbit) of the satellite ST is made public by an organization that operates the satellite ST, and the received wave information acquisition unit 32 can acquire this information from the organization via a communication network, for example.

[0114] For example, the aquarium determination unit 39 calculates the reflection position of the reflected wave Pr transmitted from the satellite ST and received by the receiver 2, based on the position of the satellite ST and the position of the antenna of the receiver 2. The aquarium determination unit 39 may then determine the aquarium subunit AQs located at the reflection position as the aquarium subunit AQs that will contain water W. The aquarium determination unit 39 may also determine the aquarium subunit AQs located at the reflection position and the aquarium subunit AQs adjacent to the aquarium subunit AQs as the aquarium subunits AQs that will contain water W. In the example shown in FIG. 16, the aquarium determination unit 39 determines the aquarium subunit AQs located at the reflection position and the aquarium subunit AQs adjacent to the aquarium subunit AQs, which are surrounded by a thick-line rectangle, as the aquarium subunits AQs that will contain water W.

[0115] This allows water W to be contained in the aquarium subunits AQs determined by the aquarium determination unit 39, and water W not to be contained in the aquarium subunits AQs not determined by the aquarium determination unit 39. In the example shown in Fig. 16, the numerical value written in each aquarium subunit AQs indicates the water level d of the water W. In this example, the water level d of the water W contained in the aquarium subunits AQs surrounded by a thick-lined rectangle that have been determined to be the aquarium subunits AQs that will contain water W is 0.1 m (meters), and the water level d of the water W contained in the aquarium subunits AQs not surrounded by a thick-lined rectangle that have not been determined to be the aquarium subunits AQs that will contain water W is 0.0 m.

[0116] The input unit 31-2 can accept input of water level information indicating the water level d of the water W contained in the water tank subunit AQs determined by the water tank determination unit 39.

[0117] The output unit 36-3 outputs water tank information indicating the water tank subunit AQs that contains the water W, as determined by the water tank determination unit 39. The output unit 36-3 may display the water tank information on a display device, or may transmit the water tank information to another device via a communication network. The other device may be, for example, a water supply system that supplies water W to the water tank subunit AQs, or a water supply and drainage control device that controls a drainage system that drains water from the water tank subunit AQs. In this way, the water supply and drainage control device can control the water supply system to supply water W to the water tank subunit AQs determined by the water tank determination unit 39, or the drainage system to drain water from the water tank subunit AQs.

[0118] <Control device operation> Next, an operation using the control device 3-3 according to the fourth embodiment will be described. Fig. 17 is a flowchart showing an example of an operation using the control device 3-3 according to the fourth embodiment. The operation of the control device 3-3 described with reference to Fig. 17 includes a control method executed by the control device 3-3 according to the fourth embodiment.

[0119] In step S51, the received wave information acquisition unit 32 acquires position information indicating the position of the satellite ST.

[0120] In step S52, the aquarium determination unit 39 determines the aquarium subunit AQs that contains the water W from among the plurality of aquarium subunits AQs based on the position of the satellite ST indicated by the position information.

[0121] In step S53, the water supply facility supplies water W to the aquarium subunits AQs determined in step S52.

[0122] In step S54, the water level meter 1 measures the water level d.

[0123] In step S55, water level information indicating the water level d measured in step S54 is input to the control device 3-2, whereby the input unit 31 receives the input of water level information indicating the water level d.

[0124] In step S56, the received wave information acquisition unit 32 acquires received wave information indicating the received wave based on the direct electromagnetic wave Pd transmitted from the satellite ST and received by the receiver 2 and the reflected wave Pr of the electromagnetic wave reflected on the surface of the water W.

[0125] In step S57, the phase calculation unit 33 calculates the phase φ in a sine function when the signal-to-noise ratio of the signal indicating the received wave included in the received wave information acquired in step S56 is fitted to the sine function with the satellite elevation angle E as a variable.

[0126] In step S58, the regression equation calculation unit 34 calculates a regression equation that indicates the relationship between the water level d and the phase φ.

[0127] In step S59, the determination unit 35 determines whether or not the regression equation has been calculated a predetermined number of times or more.

[0128] If it is determined in step S59 that the regression equation has been calculated a predetermined number of times or more, then in step S60, the determination unit 35 causes the output unit 36-3 to output regression equation information including the regression equation last calculated in step S58.

[0129] If it is determined in step S59 that the regression equation has not been calculated the predetermined number of times or more, then in step S61 the determination unit 35 determines whether or not the water level d is less than a predetermined water level threshold value.

[0130] If it is determined in step S61 that the water level d is equal to or greater than a predetermined water level threshold (if the predetermined water level threshold is the depth a of the water tank AQ, the water level d is equal to the predetermined water level threshold), then in step S60, the determination unit 35 causes the output unit 36-3 to output regression equation information including the regression equation last calculated in step S58.

[0131] If it is determined in step S61 that the water level d is less than the predetermined water level threshold, the determination unit 35 causes the output unit 36-3 to output a command to change the water level d, and the process returns to step S51 and is repeated.

[0132] In step S53 described above, the water supply equipment supplies water W to the aquarium subunit AQs indicated in the aquarium information, but this is not limiting. For example, operation may be started from an initial state in which the aquarium subunit AQs indicated in the aquarium information is filled with water W, and in step S53, the drainage equipment may discharge the water W from the aquarium subunit AQs indicated in the aquarium information.

[0133] Furthermore, the measuring device 4 in the first embodiment may store the regression equation calculated by the control device 3-3 in the fourth embodiment and measure the soil moisture content using the regression equation.

[0134] As described above, according to the fourth embodiment, the aquarium AQ is composed of a plurality of aquarium subunits AQs that contain water W. The plurality of aquarium subunits AQs are installed around the receiver 2. The control device 3-3 further includes an aquarium determination unit 39 that determines, based on the position of the satellite ST, which of the plurality of aquarium subunits AQs will contain the water W. The input unit 31-3 receives input of water level information indicating the water level d of the water W contained in the determined aquarium subunit AQs. This makes it possible to calculate the regression equation by storing water W in only some of the aquarium subunits AQs that make up the aquarium AQ. This makes it possible to reduce the amount of water W used to calculate the regression equation.

[0135] <Modification> In the first embodiment described above, the control system 100 may further include a circulation system 600 for water W supplied to and drained from the water tank AQ. The circulation system 600 includes, for example, a drain pan 61, a grating 62, a pump 63, a drain pipe 64, a water storage tank 65, a water supply pipe 66, a valve 67, a water supply and drainage control device 68, and a tank water level gauge 69, as shown in FIG.

[0136] The drain pan 61 stores the water W discharged from the water tank AQ.

[0137] The grating 62 has one or more legs 621 and a shelf 622. One vertical end of the leg 621 is attached to the bottom of the drain pan 61, and the other end is positioned higher than the upper end of the drain pan 61. The shelf 622 is a plate-shaped member, and is attached to the upper side of the other end of the leg 621 so that the plane of the member is approximately horizontal. The water tank AQ is provided on the upper surface of the shelf 622. As a result, a double floor is formed by the bottom surface of the drain pan 61 and the shelf 622 of the grating 62.

[0138] The pump 63 pumps up the water W contained in the drain pan 61 and sends it to the water storage tank 65 via the drain pipe 64.

[0139] The drain pipe 64 is a pipe that connects the pump 63 and the water storage tank 65. The water discharged from the pump 63 is transported to the water storage tank 65 through the drain pipe 64.

[0140] The water storage tank 65 stores the water W delivered from the pump 63 and transported through the drain pipe 64 .

[0141] The water supply pipe 66 is a pipe connected to the drain outlet of the water storage tank 65. Water W delivered from the water storage tank 65 passes through the water supply pipe 66 and is supplied to the water tank AQ.

[0142] Valve 67 is attached to water supply pipe 66. When valve 67 is opened under the control of water supply and drainage control device 68, water W is supplied to water tank AQ through water supply pipe 66. When valve 67 is closed under the control of water supply and drainage control device 68, the supply of water W to water tank AQ is stopped. Valve 67 can be a solenoid valve.

[0143] The water supply and drainage control device 68 controls the supply and discharge of water W in the water tank AQ. Specifically, the water supply and drainage control device 68 controls the pump 63 to pump up the water W stored in the drain pan 61 and send it out through the drain pipe 64. The water supply and drainage control device 68 also controls the valve 67 to open so that the water W is supplied from the water storage tank 65 to the water tank AQ, and controls the valve 67 to close so that the supply of water W from the water storage tank 65 to the water tank AQ is stopped.

[0144] The tank water level gauge 69 measures the water level d of the water W stored in the water storage tank 65. As a result, for example, the water supply and drainage control device 68 may control the pump 63 to stop sending the water W to the water storage tank 65 when the water level d of the water W stored in the water storage tank 65 is equal to or higher than a predetermined threshold value.

[0145] In addition, the control system 100-2 according to the third embodiment or the control system 100-3 according to the fourth embodiment may similarly further include a drain pan 61, a grating 62, a pump 63, a drain pipe 64, a water storage tank 65, a water supply pipe 66, a valve 67, a water supply and drainage control device 68, and a tank water level gauge 69.

[0146] <Program> The above-described control devices 3, 3-1, 3-2, and 3-3 and the measurement device 4 can be realized by a computer 101. Furthermore, a program for causing the above-described control devices 3, 3-1, 3-2, and 3-3 and the measurement device 4 to function may be provided. Furthermore, the program may be stored in a storage medium or provided via a network. FIG. 19 is a block diagram showing a schematic configuration of the computer 101 functioning as the control device 3. The computers functioning as the control devices 3-1, 3-2, and 3-3 and the measurement device 4 may also be configured similarly to the computer 101. Here, the computer 101 may be a general-purpose computer, a dedicated computer, a workstation, a PC (Personal Computer), an electronic notepad, or the like. The program instructions may be program code, code segments, or the like for executing necessary tasks.

[0147] 19, a computer 101 includes a processor 110, a read-only memory (ROM) 120, a random access memory (RAM) 130, a storage 140, an input unit 150, an output unit 160, and a communication interface (I / F) 170. Each component is connected to each other via a bus 180 so as to be able to communicate with each other. The processor 110 is specifically a central processing unit (CPU), a micro processing unit (MPU), a graphics processing unit (GPU), a digital signal processor (DSP), a system on a chip (SoC), or the like, and may be configured by a plurality of processors of the same type or different types.

[0148] The processor 110 controls each component and executes various arithmetic processes. That is, the processor 110 reads a program from the ROM 120 or the storage 140 and executes the program using the RAM 530 as a work area. The processor 110 controls each component and executes various arithmetic processes in accordance with the program stored in the ROM 120 or the storage 140. In the above-described embodiment, the program according to the present disclosure is stored in the ROM 120 or the storage 140.

[0149] The program may be stored in a storage medium readable by the computer 101. Using such a storage medium, the program can be installed in the computer 101. Here, the storage medium on which the program is stored may be a non-transitory storage medium. The non-transitory storage medium is not particularly limited, and may be, for example, a CD-ROM, a DVD-ROM, or a USB (Universal Serial Bus) memory. Furthermore, the program may be downloaded from an external device via a network.

[0150] The ROM 120 stores various programs and various data. The RAM 530 temporarily stores programs or data as a working area. The storage 140 is configured with an HDD (Hard Disk Drive) or an SSD (Solid State Drive) and stores various programs including the operating system and various data.

[0151] The input unit 150 includes one or more input interfaces that receive input operations from a user and acquire information based on the user operations. For example, the input unit 150 is, but is not limited to, a pointing device, a keyboard, a mouse, etc.

[0152] The output unit 160 includes one or more output interfaces that output information. For example, the output unit 160 is a display that outputs information as a video or a speaker that outputs information as an audio, but is not limited to these. Note that if the output unit 160 is a touch panel display, it also functions as the input unit 150.

[0153] The communication interface (I / F) 170 is an interface for communicating with an external device.

[0154] All publications, patent applications, and technologies mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, and technology was specifically and individually indicated to be incorporated by reference.

[0155] Although the above-described embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present disclosure. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications or alterations are possible without departing from the scope of the claims. [Explanation of symbols]

[0156] 1 Water level gauge 2 Receivers 3, 3-1, 3-2, 3-3 Control device 4. Measuring equipment 5. Soil moisture meter 31, 31-1, 31-2, 31-3 Input section (first input section) 32, 32-2 Received wave information acquisition unit (first received wave information acquisition unit) 33 Phase calculation section 34, 34-1 Regression equation calculation section 35 Judgment section 36, 36-2, 36-3 Output section (first output section) 37 Phase memory section 38 Detection range determination unit 39 Aquarium Decision Section 41 Input section (second input section) 42 received wave information acquisition unit (second received wave information acquisition unit) 43 Regression memory section 44 Soil moisture measurement unit 45 Output section (second output section) 61 Drain pan 62 Grating 63 Pump 64 Drain pipe 65 Water Tank 66 Water supply pipe 67 Valve 68 Water supply and drainage control device 69 Tank water level gauge 100, 100-1, 100-2 control system 101 Computer 110 processors 120 ROM 130 RAM 140 Storage 150 Input section 160 Output section 170 Communication Interface 180 Bus 600 Circulation System 621 Legs 622 Shelf AQ Aquarium AQs Aquarium Subunit GR ground IS installation stand PD direct wave Pr reflected wave SL soil ST satellite W water

Claims

1. an input unit that receives input of water level information indicating the water level of the water contained in the water tank; a received wave information acquiring unit that acquires received wave information indicating received waves based on direct waves of electromagnetic waves transmitted from a satellite and received by a receiver, and waves reflected by the surface of the water from the direct waves of electromagnetic waves; a phase calculation unit that calculates a phase of a sine function corresponding to the signal-to-noise ratio when the signal-to-noise ratio of the signal representing the received wave is fitted to the sine function with the satellite elevation angle as a variable; a regression equation calculation unit that calculates a regression equation that indicates the relationship between the water level and the phase; A control device comprising:

2. the input unit accepts input of condition information indicating conditions related to reception of electromagnetic waves from a satellite by a receiver; an output unit that outputs regression equation information including the regression equation and condition information corresponding to the regression equation; The control device according to claim 1 , wherein the condition information includes information indicating characteristics of the satellite and the electromagnetic wave, and information indicating the receiver and antenna.

3. the water tank is composed of a plurality of water tank sub-units for containing water; the received wave information acquisition unit acquires the received wave information each time water is drained from some of the water tank subunits that contained water; a phase storage unit that stores the phase calculated by the phase calculation unit each time the received wave information is acquired and water tank subunit information that identifies the water tank subunit containing water when the phase is calculated; 3. The control device according to claim 1, further comprising: a detection range determination unit that determines a detection range in which soil moisture content is detected based on the received wave information, based on the difference between the two phases most recently stored in the phase memory unit.

4. the water tank is composed of a plurality of water tank sub-units for containing water; the plurality of aquarium subunits are arranged around the receiver; a water tank determination unit that determines which of the plurality of water tank subunits will contain the water based on the position of the satellite; The control device according to claim 1 or 2, wherein the input unit receives input of water level information indicating the determined water level of the water contained in the water tank subunit.

5. In a control method executed by a control device, receiving input of water level information indicating the water level of the water contained in the water tank; a step of acquiring received wave information indicating received waves based on direct waves of electromagnetic waves transmitted from a satellite and received by a receiver and waves reflected by the surface of the water; a step of fitting a signal-to-noise ratio of the signal representing the received wave to a sine function having a satellite elevation angle as a variable, and calculating a phase of the sine function corresponding to the signal-to-noise ratio; calculating a regression equation showing a relationship between the water level and the phase; A control method comprising:

6. supplying water to a water tank containing soil until the soil is saturated with water; a measuring step of measuring a soil moisture content, which is the amount of moisture contained in the soil; an acquisition step of acquiring received wave information indicating the received wave when the soil moisture content was measured, based on a direct wave of an electromagnetic wave transmitted from a satellite and received by a receiver, and a wave reflected from the surface of the soil of the electromagnetic wave; a phase calculation step of calculating a phase of a sine function corresponding to the signal-to-noise ratio when the signal-to-noise ratio of the signal representing the received wave is fitted to the sine function with the satellite elevation angle as a variable; a regression equation calculation step of calculating a regression equation showing the relationship between the soil moisture content and the phase; a first determination step of determining whether the regression equation has been calculated a predetermined number of times or more; a second determination step of determining whether the soil moisture content is less than a predetermined soil moisture content threshold value when it is determined that the regression equation has not been calculated the predetermined number of times or more, a control method in which, when it is determined that the soil moisture content is equal to or greater than a predetermined soil moisture content threshold, the measurement step, the acquisition step, the phase calculation step, and the regression equation calculation step are repeated in order until it is determined that the regression equation has been calculated the predetermined number of times or more, or until it is determined that the soil moisture content is less than the predetermined soil moisture content.

7. A control system including a receiver for receiving electromagnetic waves transmitted from a satellite and a control device, The control device an input unit that receives input of water level information indicating the water level of the water contained in the water tank; a received wave information acquiring unit that acquires received wave information indicating received waves based on direct waves of electromagnetic waves transmitted from a satellite and received by a receiver, and waves reflected by the surface of the water from the direct waves of electromagnetic waves; a phase calculation unit that calculates a phase of a sine function corresponding to the signal-to-noise ratio when the signal-to-noise ratio of the signal representing the received wave is fitted to the sine function with the satellite elevation angle as a variable; a regression equation calculation unit that calculates a regression equation that indicates the relationship between the water level and the phase; A control system having:

8. A program for causing a computer to function as the control device according to claim 1 or 2.

Images