Measurement device, measurement system, and measurement method

Abstract

To provide a measurement device for measuring the moisture content in a medium that improves the accuracy in measuring the moisture content.SOLUTION: A transmitter transmits via a cable an electrical signal including incident waves to one of a pair of probes each having the cable embedded. A receiver receives via the cable reflection waves which are the incident waves reflected on the one of the pair of probes and transmission waves that have transmitted through a medium between the pair of probes. A processor calculates a back-and-forth delay time which is a time taken for the electrical signal to travel back and forth through the cable, and performs processing for measuring the moisture content included in the medium on the basis of the back-and-forth delay time and a propagation transmission time which is a time for electromagnetic waves and the electrical signal to propagate and transmit through the medium and the cable.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present technology relates to a measurement device, a measurement system, and a measurement method, and more particularly to a measurement device, a measurement system, and a measurement method provided with a pair of probes. [Background technology]

[0002] Conventionally, devices and instruments for measuring the moisture content in a medium such as soil have been widely used in fields such as agriculture and environmental surveys. For example, a sensor device has been proposed that measures the moisture content from the propagation delay time of electromagnetic waves propagating through a medium between a pair of probes (see, for example, Patent Document 1). This sensor device connects the pair of probes to a transmitter and a receiver via a cable, transmits an electrical signal from the transmitter to the receiver, and calculates the delay time from transmission to reception. The sensor device then stores in advance the transmission time of the electrical signal through the cable as a fixed error, and calculates the propagation delay time of the electromagnetic wave propagating through the medium by subtracting this error from the calculated delay time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 221051 Summary of the Invention [Problem to be solved by the invention]

[0004] The sensor device described above aims to improve the accuracy of moisture content measurement by subtracting the error when calculating the propagation delay time of the electromagnetic wave. However, the length of the cable may change due to thermal expansion, and the error may also fluctuate due to this change in length. Therefore, in the sensor device described above, where the error is a fixed value, there is a risk that the moisture content measurement accuracy will decrease when the cable thermally expands.

[0005] This technology was developed in light of these circumstances, and aims to improve the accuracy of moisture content measurement in a measuring device that measures the moisture content in a medium. [Means for solving the problem]

[0006] The present technology has been made to solve the above-mentioned problems, and a first aspect thereof is a measurement device and a measurement method thereof, including: a transmitter that transmits an electric signal including an incident wave via a cable to one of a pair of probes, each having a cable embedded in the cable; a receiver that receives via the cable a reflected wave obtained by reflecting the incident wave from one of the pair of probes and a transmitted wave that has transmitted through a medium between the pair of probes; and a processing unit that calculates a round-trip delay time, which is the time it takes for the electric signal to go round trip through the cable, and measures the amount of moisture contained in the medium based on the round-trip delay time and a propagation transmission time, which is the time it takes for the electromagnetic wave and the electric signal to propagate and transmit through the medium and the cable. This provides the effect of measuring the amount of moisture from the round-trip delay time and the propagation transmission time.

[0007] In addition, in this first aspect, an outer shell may be further provided that isolates the pair of probes from the medium, thereby providing the effect of making the round trip delay time constant regardless of the amount of moisture.

[0008] In addition, in this first aspect, the outer shell may be formed of an electromagnetic wave transmitting material, thereby providing the effect of allowing electromagnetic waves to pass through the outer shell.

[0009] In addition, in this first aspect, a spacer that keeps the distance between the pair of probes constant can be further provided, thereby providing the effect of defining the distance between the probes.

[0010] In addition, in this first aspect, the spacer may be made of an electromagnetic wave transmitting material, thereby providing the effect of allowing electromagnetic waves to pass through the spacer.

[0011] In addition, in the first aspect, an outer edge of the spacer that extends between the pair of probes and is closer to the antenna portion of each of the pair of probes may be arc-shaped, thereby providing an effect of reducing noise.

[0012] In this first aspect, the distance from each of the antenna portions of the pair of probes to the lower end of the spacer may be greater than the inter-antenna distance, which is the distance between the antenna portions, preferably greater than twice the inter-antenna distance, more preferably greater than three times the inter-antenna distance, and may be less than the length of the probes, thereby providing an effect of reducing noise.

[0013] In addition, in this first aspect, the device may further include a control unit that performs control to transmit the incident wave, a process of calculating a ratio of the complex amplitudes of the incident wave and the reflected wave as a reflection coefficient, and a process of calculating a ratio of the complex amplitudes of the incident wave and the transmitted wave as a transmission coefficient, and the processing unit may calculate the round-trip delay time and the propagation transmission time based on the reflection coefficient and the transmission coefficient, thereby providing the effect of measuring the moisture content based on the round-trip delay time and the propagation transmission time calculated from the reflection coefficient and the transmission coefficient.

[0014] In addition, in this first aspect, the control unit and the processing unit may be provided on a predetermined semiconductor chip, thereby providing an effect of reducing the number of chips in the measuring device.

[0015] In addition, in this first aspect, the control unit may be provided on a predetermined semiconductor chip, and the processing unit may be provided on a semiconductor chip different from the semiconductor chip, thereby providing an effect that the moisture content is measured in a measurement device provided with multiple semiconductor chips.

[0016] In addition, in this first aspect, the device may further include a communication unit that wirelessly transmits the reflection coefficient and the transmission coefficient to the processing unit, thereby providing an effect that the moisture content can be measured even if the processing unit is located in a remote location.

[0017] In addition, in this first aspect, a directional coupler may be further provided that separates the electrical signal transmitted through the cable into the incident wave and the reflected wave, thereby providing the effect of allowing each of the separated incident wave and reflected wave to be received.

[0018] In addition, in this first aspect, the receiver may include an incident wave receiver that receives the incident wave, a reflected wave receiver that receives the reflected wave, and a transmitted wave receiver that receives the transmitted wave, thereby achieving the effect of receiving each of the incident wave, the reflected wave, and the transmitted wave.

[0019] Moreover, in this first aspect, the incident wave may include first and second incident waves having different directions from each other, the reflected wave may include a first reflected wave corresponding to the first incident wave and a second reflected wave corresponding to the second incident wave, the transmitted wave may include a second transmitted wave corresponding to the first incident wave and a first transmitted wave corresponding to the second incident wave, the directional coupler may include a first directional coupler that separates the electrical signal into the first incident wave and the first reflected wave and a second directional coupler that separates the electrical signal into the second incident wave and the second reflected wave, the transmitter may include a first transmitter that transmits the first incident wave and a second transmitter that transmits the second incident wave, and the receiver may include a first receiver that sequentially receives the first reflected wave and the first transmitted wave and a second receiver that sequentially receives the second reflected wave and the second transmitted wave. This brings about the effect that the first and second incident waves in different directions and the corresponding reflected and transmitted waves are received.

[0020] In addition, in this first aspect, the round trip delay time may include a first round trip delay time corresponding to one of the pair of probes and a second round trip delay time corresponding to the other of the pair of probes, and the processing unit may calculate the first round trip delay time from the first incident wave and the first reflected wave, and calculate the second round trip delay time from the second incident wave and the second reflected wave. This brings about an effect that the round trip delay times corresponding to each of the pair of probes can be obtained.

[0021] In addition, in this first aspect, the processing unit may calculate a propagation delay time, which is the time it takes for the electromagnetic wave to propagate through the medium, from the round-trip delay time and the propagation transmission time, and measure the moisture content corresponding to the propagation delay time. This brings about an effect that the moisture content corresponding to the propagation delay time is measured.

[0022] In addition, in this first aspect, the processing unit may store a predetermined coefficient indicating a relationship between the propagation delay time and the moisture content, and measure the moisture content from the calculated propagation delay time and the coefficient, thereby providing an effect that the moisture content is measured from the propagation delay time and the coefficient.

[0023] A second aspect of the present technology is a measurement system including: a transmitter that transmits an electrical signal including an incident wave via a cable to one of a pair of probes, each of which is connected to a cable; a receiver that receives via the cable a reflected wave obtained by reflecting the incident wave from one of the pair of probes and a transmitted wave that has transmitted through a medium between the pair of probes; a control unit that performs processing to control the transmission of the incident wave and to calculate a ratio of the complex amplitudes of the incident wave and the reflected wave as a reflection coefficient; and a processing unit that performs processing to calculate a round-trip delay time, which is the time it takes for the electrical signal to travel back and forth through the cable, from the reflection coefficient and to measure the amount of moisture contained in the medium based on the round-trip delay time and a propagation transmission time, which is the time it takes for the electromagnetic wave and the electrical signal to propagate and transmit through the medium and the cable. This provides the effect of measuring the amount of moisture based on the round-trip delay time and the propagation transmission time obtained from the reflection coefficient. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a block diagram showing an example of the configuration of a measurement device according to a first embodiment of the present technology; [Figure 2] 1 is an example of an external view of a sensor head according to a first embodiment of the present technology; [Figure 3] 1 is a diagram illustrating an example of an antenna unit and an equivalent circuit according to a first embodiment of the present technology. [Figure 4] 4 is a graph showing an example of a waveform of an impulse response of a reflection coefficient according to the first embodiment of the present technology. [Figure 5] 10 is a graph showing an example of a waveform of an impulse response of a reflection coefficient in a comparative example. [Figure 6] 1 is a block diagram showing an example of the configuration of a measurement unit according to a first embodiment of the present technology. [Figure 7] 1 is a diagram illustrating an example of a configuration of a directional coupler according to a first embodiment of the present technology. [Figure 8] 1 is a circuit diagram showing an example configuration of a transmitter and a receiver according to a first embodiment of the present technology. [Figure 9] 3 is a block diagram showing a configuration example of a control unit according to the first embodiment of the present technology. FIG. [Figure 10] 1 is a block diagram showing an example of the configuration of a signal processing unit according to a first embodiment of the present technology. [Figure 11] 2A to 2C are diagrams for explaining propagation paths and transmission paths of electromagnetic waves and electric signals in the first embodiment of the present technology. [Figure 12] 4 is a graph showing an example of a waveform of an impulse response of a reflection coefficient according to the first embodiment of the present technology. [Figure 13] 4 is a graph showing an example of a waveform of an impulse response of a transmission coefficient according to the first embodiment of the present technology. [Figure 14] 4 is a graph showing an example of the relationship between the round-trip delay time and the propagation transmission time and the moisture content in the first embodiment of the present technology. [Figure 15] 4 is a graph showing an example of the relationship between propagation delay time and moisture content in the first embodiment of the present technology. [Figure 16] 10 is a block diagram showing an example of the configuration of a measurement device in which the cable is further extended according to the first embodiment of the present technology. FIG. [Figure 17] 5 is a flowchart showing an example of the operation of the measurement device according to the first embodiment of the present technology. [Figure 18] FIG. 10 is a block diagram showing an example of the configuration of a measurement device according to a second embodiment of the present technology. [Figure 19] FIG. 10 is a block diagram showing an example configuration of a measurement unit according to a second embodiment of the present technology. [Figure 20] FIG. 10 is a block diagram showing an example configuration of a measurement system according to a third embodiment of the present technology. [Figure 21] FIG. 13 is a block diagram showing an example configuration of a measurement unit according to a fourth embodiment of the present technology. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, modes for carrying out the present technology (hereinafter referred to as embodiments) will be described in the following order. 1. First embodiment (example of calculating round trip delay time and propagation transmission time) 2. Second embodiment (example of determining round trip delay time and propagation transmission time using one semiconductor chip) 3. Third embodiment (example of wireless communication to determine round trip delay time and propagation transmission time) 4. Fourth embodiment (example of finding round-trip delay time and propagation transmission time by changing transmission direction)

[0026] <1. First embodiment> [Example of measurement device configuration] 1 is a block diagram showing an example configuration of a measurement device 100 according to a first embodiment of the present technology. The measurement device 100 measures the amount of moisture contained in a medium M, and includes a sensor device 110 and a signal processing unit 400. The medium M may be, for example, soil for growing agricultural crops.

[0027] The sensor device 110 acquires data necessary for measuring the moisture content as measurement data. The contents of the measurement data will be described later. The sensor device 110 transmits the measurement data to the signal processing unit 400 via a signal line 409. The signal processing unit 400 measures the moisture content using the measurement data.

[0028] The sensor device 110 also has a sensor head 200 and a measurement unit 300. The sensor head 200 is a component made up of probes 201 and 202. These probes 201 and 202 are connected to the measurement unit 300 via cables 308 and 309. Coaxial cables, for example, are used as the cables 308 and 309. These cables 308 and 309 are connected to the probes 201 and 202 by embedding their respective tips inside the probes 201 and 202. The measurement unit 300 generates measurement data by causing one of the probes 201 and 202 to transmit electromagnetic waves EW and causing the other probe to receive the electromagnetic waves EW.

[0029] Furthermore, the measurement unit 300 and the signal processing unit 400 are implemented on different semiconductor chips. As will be described later, the circuits of the measurement unit 300 and the signal processing unit 400 can also be implemented on the same semiconductor chip.

[0030] Furthermore, the measurement unit 300 may be configured to include an electronic circuit board with a wiring layer and a semiconductor chip mounted on the electronic circuit board. The measurement unit 300 may be configured to include the electronic circuit board, the semiconductor chip, and a housing that houses them. The cables 308 and 309 may be connected to the semiconductor chip via the wiring layer provided on the electronic circuit board.

[0031] The size of the measurement unit 300, which is composed of an electronic circuit board and a semiconductor chip, or the housing that houses it, may be such that (1) its size in the direction of extension (the board plane direction of the electronic circuit board) fits into an approximately rectangular shape with one side being 1 to 20 centimeters (cm) long and the other side perpendicular to this being 1 to 40 centimeters (cm) long, and (2) its thickness may be, for example, 2 to 20 millimeters (mm).

[0032] The measuring unit 300 may be arranged in at least two ways. That is, (1) the measuring unit 300 may be arranged so that the direction in which the measuring unit 300 extends is parallel to the direction in which the probes 201 and 202 extend. Alternatively, (2) the measuring unit 300 may be arranged so that the direction in which the measuring unit 300 extends is perpendicular to the direction in which the probes 201 and 202 extend.

[0033] When the signal processing unit 400 is placed in a housing different from that of the sensor device 110, a system including the sensor device 110 and the signal processing unit 400 can also be treated as a measurement system.

[0034] [Sensor head configuration example] 2 is an example of an external view of a sensor head 200 according to the first embodiment of the present technology. The sensor head 200 has probes 201 and 202. The length of each of the probes 201 and 202 is, for example, 75 to 150 millimeters (mm). The thickness of each of the probes 201 and 202 (diameter, or width of the probe cross section) is, for example, 3 to 30 millimeters (mm). These probes 201 and 202 are disposed in a medium such as soil, and each have an antenna unit 210 capable of transmitting and receiving electromagnetic waves of a predetermined frequency between the probes 201 and 202.

[0035] The probes 201 and 202 are embedded in the medium so that the distance between their respective antenna portions 210 is a predetermined value D. For example, these probes are embedded in the medium in a substantially vertical orientation. Note that, as long as the distance between the antenna portions 210 is D, their orientation is not limited to a vertical orientation.

[0036] Antenna unit 210 is provided at or near the tip end (in other words, the end) of probes 201 and 202, and transmits and receives electromagnetic waves. Although antenna unit 210 is provided at the tip end of probes 201 and 202, the configuration is not limited to this. For example, antenna unit 210 can also be provided at the center of probes 201 and 202.

[0037] Furthermore, the antenna section 210 is configured as a minute antenna formed to a size that does not cause resonance in the probes 201 and 202. This makes it possible to suppress a decrease in measurement accuracy due to resonance in the probes 201 and 202.

[0038] 1 (coaxial cables) are embedded inside probes 201 and 202, respectively, as described above. A portion of this coaxial cable is opened and used as antenna section 210. The outer periphery of the coaxial cable other than antenna section 210 is covered with electromagnetic wave absorbing material 240. Electromagnetic wave absorbing material 240 can suppress leakage of electromagnetic waves from areas other than the opening.

[0039] Although Ni-Zn ferrite is mainly used as the electromagnetic wave absorbing material 240, it is not limited to this and other high permeability materials such as sendust or permalloy may be used depending on the frequency of the electromagnetic waves EW, etc. Furthermore, the electromagnetic wave absorbing material 240 may be omitted as necessary, or may be provided only on one of the probes 201 and 202.

[0040] The size of the distance D between the antenna units 210 is not particularly limited. If the distance D is too large, the electromagnetic waves EW propagating through the medium M will be attenuated to a large extent, and sufficient reception strength may not be obtained. On the other hand, if the distance D is too small, observation may become technically difficult. Taking these factors into consideration, the distance D is set to an appropriate value. For example, the distance D is 25 to 75 millimeters (mm).

[0041] A spacer 260 is disposed between the probes 201 and 202 to define the distance between the antenna units 210. The outer periphery of each of the probes 201 and 202 is covered with an outer shell 225 having a thickness of 1 to 3 millimeters (mm) to isolate the probes from the medium. The spacer 260 and the outer shell 225 are made of an electromagnetically transparent material. Examples of the electromagnetically transparent material include polymeric materials, glass, and inorganic materials such as PTEF (PolyTEtraFluoroethylene). Examples of polymeric materials include PC (PolyCarbonate), PES (PolyEtherSulfone), PEEK (PolyEtherEtherKetone), and PSS (PolyStyrene Sulfonic Acid). Other polymeric materials include PMMA (PolyMethylMethAcrylate) and PET (PolyEthylene Terephthalate).

[0042] The thickness of the spacer 260 may be smaller than the size and thickness of the measurement unit 300, which is configured to include an electronic circuit board and a semiconductor chip. For example, when the measurement unit 300 is arranged so that the direction in which the measurement unit 300 extends is parallel to the direction in which the probes 201 and 202 extend, the thickness of the spacer 260 may be smaller than the thickness of the measurement unit 300, preferably smaller than 1 / 2, and more preferably smaller than 1 / 3. Alternatively, when the measurement unit 300 is arranged so that the direction in which the measurement unit 300 extends is perpendicular to the direction in which the probes 201 and 202 extend, the thickness of the spacer 260 may be smaller than the length of one direction in which the measurement unit 300 extends, preferably smaller than 1 / 2, and more preferably smaller than 1 / 3. The thickness of the spacer 260 may be smaller than, preferably smaller than 1 / 2, and more preferably smaller than 1 / 3 the thickness (diameter or width of the probe cross section) of at least one of the probes 201 and 202. The thickness of the spacer 260 may be, for example, 1 to 3 millimeters (mm).

[0043] The configuration in which the thickness of the spacer 260 is smaller than the thickness of the measurement unit 300, or smaller than the length of the measurement unit 300 in one direction, or smaller than the thickness (diameter or width of the probe cross section) of at least one of the probes 201 and 202, provides an effect unique to a moisture sensor that measures the propagation delay time of electromagnetic waves between antennas. Even if the spacer 260 is made of an electromagnetically transparent material, depending on the material, the electromagnetic waves radiated from the transmitting antenna may be reflected by the spacer and received by the receiving antenna, resulting in noise. By configuring the thickness of the spacer 260 as described above, the noise reflected by the spacer 260 can be reduced compared to a configuration that does not include this configuration. This effect of reducing the noise by reducing the spacer thickness does not occur in moisture sensors other than those that measure the propagation delay time of electromagnetic waves between antennas, but is an effect that occurs only in a moisture sensor that measures the propagation delay time of electromagnetic waves between antennas.

[0044] Note that the distance d from the antenna portions (210 and 220) of the pair of probes (201 and 202) to the bottom end of the spacer 260 is preferably greater than the distance D between the antennas. In particular, the distance d is preferably greater than twice the distance D between the antennas. Furthermore, the distance d is more preferably greater than three times the distance D between the antennas and less than the length of each of the probes 201 and 202. Even if the spacer 260 between the probes 201 and 202 is formed of an electromagnetically transparent material, depending on the material, microwaves radiated from the transmitting antenna may be reflected by the spacer and received by the receiving antenna, resulting in noise. As described above, this noise can be reduced by moving the spacer 260 away from the antenna. This "effect of reducing noise by moving the spacer 260 away from the antenna" does not occur in moisture sensors other than those that measure propagation delay between antennas, but occurs only in a moisture sensor that measures propagation delay between antennas, as in the present technology.

[0045] Furthermore, among the outer edges of spacer 260 that extend between the pair of probes (201 and 202), the outer edge closer to the antenna units (210 and 220) is arc-shaped as shown in the figure. When the outer edge is arc-shaped rather than straight, noise caused by microwaves radiated from the transmitting antenna being reflected by spacer 260 and received by the receiving antenna can be reduced more effectively. This "noise reduction effect achieved by making spacer 260 arc-shaped" does not occur in moisture sensors other than those that measure propagation delay between antennas, but occurs precisely because this is a moisture sensor that measures propagation delay between antennas.

[0046] [Antenna configuration example] 3 is a diagram showing an example of the antenna unit 210 and an equivalent circuit according to the first embodiment of the present technology. In the drawing, "a" is an enlarged view of the antenna unit 210. In the drawing, "b" is an example of the equivalent circuit of the antenna unit 210.

[0047] The cable 308 (such as a coaxial cable) embedded in the probe 201 has a core 211 and a shield 212. The thickness and length of the cable are not particularly limited and may be of any thickness and length. As shown in the example of a in the figure, the core 211 is made of a copper wire and the shield 212 is made of a copper pipe, but the shield 212 may also be made of a copper wire mesh.

[0048] An opening is made in a portion near the tip of cable 308 (such as a coaxial cable), and electrode portion 213 is attached. This allows antenna portion 210 of each of probes 201 and 202 to function as a minute dipole antenna with a length of approximately 4 to 10 millimeters (mm). The opening has an opening shape such as rectangular, circular, elliptical, or oval. The major axis of the opening can be set appropriately depending on the wavelength of the electromagnetic wave used.

[0049] As shown in FIG. 1B, the equivalent circuit of the antenna section 210 is represented by a circuit in which a resistor 511 is connected in parallel with fringing capacitances 512 and 513. The capacitance value of the fringing capacitance 512 is determined by the dielectric constant ε c The capacitance value of the fringing capacitance 513 is a value according to the dielectric constant ε of the material surrounding the electrode 513. * The value corresponds to

[0050] When an electrical signal is sent to either probe 201 or 202, part of the signal is reflected at the end, causing the electrical signal to travel back and forth within the coaxial cable. Of this electrical signal, the wave within the input signal is called the "incident wave," and the reflected wave of that incident wave is called the "reflected wave."

[0051] Here, a comparative example is considered in which the outer shell 225 is not provided. In this comparative example, the round trip delay time required for an electric signal to go round trip inside the coaxial cable is a function of the temperature and the dielectric constant ε * It fluctuates due to the following.

[0052] The higher the temperature, the longer the coaxial cable becomes due to thermal expansion, and the longer the delay time. * When σ changes, the fringing capacitance 512 changes accordingly, and the peak time of the impulse response of the reflection coefficient changes accordingly. Here, the reflection coefficient is the ratio of the complex amplitudes of the incident wave and the reflected wave.

[0053] 4 is a graph showing an example of the waveform of the impulse response of the reflection coefficient in the first embodiment of the present technology. In the figure, the vertical axis represents the impulse response of the reflection coefficient, and the horizontal axis represents time. The solid curve represents the waveform of the impulse response when the medium is air, and the dashed-dotted curve represents the waveform of the impulse response when the medium is water.

[0054] 5 is a graph showing an example of the waveform of the impulse response of the reflection coefficient in a comparative example in which the outer shell 225 is not provided. The vertical axis in the figure represents the impulse response of the reflection coefficient, and the horizontal axis represents time. The solid curve represents the waveform of the impulse response when the medium is air, and the dashed-dotted curve represents the waveform of the impulse response when the medium is water.

[0055] As shown in FIG. 5, when the outer shell 225 is not provided, the dielectric constant ε * fluctuates, changing the fringing capacitance 512. This causes the peak value of the impulse response to fluctuate. This fluctuation causes an error in the calculation of the round trip delay time.

[0056] In contrast, when the antenna unit 210 is isolated from the medium by providing the outer shell 225, the fringing capacitance 512 is constant, and the peak value of the impulse response does not fluctuate, as shown in Fig. 4. This allows the round-trip delay time to be calculated with high accuracy.

[0057] 6 is a block diagram showing an example configuration of a measurement unit 300 according to the first embodiment of the present technology. The measurement unit 300 includes a directional coupler 310, a transmitter 320, an incident wave receiver 330, a reflected wave receiver 340, a transmitted wave receiver 350, a communication unit 360, and a control unit 370. A vector network analyzer, for example, is used as the measurement unit 300.

[0058] Directional coupler 310 separates the electrical signal transmitted through cable 308 into an incident wave and a reflected wave. The incident wave is the wave of the electrical signal transmitted by transmitter 320, and the reflected wave is the incident wave reflected at the end of probe 201. Directional coupler 310 supplies the incident wave to incident wave receiver 330 and supplies the reflected wave to reflected wave receiver 340.

[0059] The transmitter 320 transmits an electrical signal of a predetermined frequency as a transmission signal to the probe 201 via the directional coupler 310 and the cable 308. For example, a continuous wave (CW) wave is used as the incident wave in the transmission signal. The transmitter 320 transmits the transmission signal by sequentially switching the frequency in steps of 50 megahertz (MHz) within a frequency band of, for example, 1 to 9 gigahertz (GHz).

[0060] The incident wave receiver 330 receives the incident wave from the directional coupler 310. The reflected wave receiver 340 receives the reflected wave from the directional coupler 310. The transmitted wave receiver 350 receives the transmitted wave from the probe 202. Here, the transmitted wave is an electromagnetic wave that has transmitted through the medium between the probes 201 and 202 and has been converted into an electric signal by the probe 202.

[0061] Incident wave receiver 330, reflected wave receiver 340, and transmitted wave receiver 350 perform quadrature detection and AD (Analog to Digital) conversion on the received incident wave, reflected wave, and transmitted wave, and supply the data to control unit 370 as received data.

[0062] The incident wave receiver 330, the reflected wave receiver 340, and the transmitted wave receiver 350 are examples of receivers described in the claims.

[0063] The control unit 370 controls the transmitter 320 to transmit a transmission signal including an incident wave, and performs processing to determine the reflection coefficient and transmission coefficient. Here, the reflection coefficient is the ratio of the complex amplitudes of the incident wave and the reflected wave, as described above. The transmission coefficient is the ratio of the complex amplitudes of the incident wave and the transmitted wave. The control unit 370 supplies the determined reflection coefficient and transmission coefficient to the communication unit 360.

[0064] The communication section 360 transmits data indicating the reflection coefficient and transmission coefficient as measurement data to the signal processing unit 400 via a signal line 409 .

[0065] In order to measure the reflection coefficient and transmission coefficient accurately, the frequency characteristics of the directional coupler 310, transmitter 320, and receiver (such as incident wave receiver 330) are calibrated before the measurement.

[0066] [Configuration example of directional coupler] 7 is a diagram showing an example configuration of a directional coupler 310 according to the first embodiment of the present technology. This directional coupler 310 includes transmission lines 311, 312, and 313, and termination resistors 314 and 315. This directional coupler 310 can be implemented by, for example, a bridge coupler, which is suitable for miniaturization.

[0067] One end of transmission line 311 is connected to transmitter 320, and the other end is connected to probe 201 via cable 308. Transmission line 312 is a line that is shorter than transmission line 311 and electromagnetically coupled to transmission line 311. One end of transmission line 312 is connected to termination resistor 314, and the other end is connected to reflected wave receiver 340. Transmission line 313 is a line that is shorter than transmission line 311 and electromagnetically coupled to transmission line 311. One end of transmission line 313 is connected to termination resistor 315, and the other end is connected to incident wave receiver 330.

[0068] With the above configuration, directional coupler 310 separates the electrical signal into an incident wave and a reflected wave, and supplies them to incident wave receiver 330 and reflected wave receiver 340 .

[0069] [Example of transmitter and receiver configuration] 8 is a circuit diagram showing an example configuration of a transmitter 320 and a receiver according to the first embodiment of the present technology. In the figure, "a" is a circuit diagram showing an example configuration of the transmitter 320, and "b" is a circuit diagram showing an example configuration of the incident wave receiver 330. "c" is a circuit diagram showing an example configuration of the reflected wave receiver 340, and "d" is a circuit diagram showing an example configuration of the transmitted wave receiver 350.

[0070] As illustrated in FIG. 3A, the transmitter 320 includes a transmission signal oscillator 322 and a driver 321.

[0071] The transmission signal oscillator 322 generates an electric signal as a transmission signal under the control of the control unit 370. The driver 321 outputs the transmission signal to the directional coupler 310. This transmission signal S(t) is expressed, for example, by the following equation: S(t)=|A|cos(2πft+θ) In the above equation, t represents time, and its unit is, for example, nanoseconds (ns). |A| represents the amplitude of the transmission signal. cos() represents the cosine function. f represents frequency, and its unit is, for example, hertz (Hz). θ represents phase, and its unit is, for example, radians (rad).

[0072] As shown in FIG. 1B, the incident wave receiver 330 includes a mixer 331, a bandpass filter 332, and an analog-to-digital converter 333.

[0073] The mixer 331 performs quadrature detection by mixing two local signals with a phase difference of 90 degrees with the transmission signal. I and the quadrature component Q I The complex amplitudes of these in-phase components I I and the quadrature component Q I is expressed, for example, by the following equation: Mixer 331 supplies the complex amplitude to analog-to-digital converter 333 via band-pass filter 332 . I I = |A|cos(θ) Q I =|A|sin(θ) In the above equation, sin( ) represents the sine function.

[0074] The bandpass filter 332 passes components in a predetermined frequency band. The analog-to-digital converter 333 performs AD conversion. This analog-to-digital converter 333 generates data indicating complex amplitude through AD conversion and supplies it to the control unit 370 as received data.

[0075] As shown in Fig. 1c, the reflected wave receiver 340 includes a mixer 341, a bandpass filter 342, and an analog-to-digital converter 343. The configurations of the mixer 341, the bandpass filter 342, and the analog-to-digital converter 343 are similar to those of the mixer 331, the bandpass filter 332, and the analog-to-digital converter 333. The reflected wave receiver 340 performs quadrature detection on the reflected wave to extract an in-phase component I R and the quadrature component Q R and supplies reception data indicating the complex amplitude to the control unit 370.

[0076] As illustrated in d of the figure, the transmitted wave receiver 350 includes a receiver 351, a local signal oscillator 352, a mixer 353, a band-pass filter 354, and an analog-to-digital converter 355. The configurations of the mixer 353, the band-pass filter 354, and the analog-to-digital converter 355 are similar to those of the mixer 331, the band-pass filter 332, and the analog-to-digital converter 333.

[0077] The receiver 351 receives an electrical signal including a transmitted wave via the cable 309 and outputs the signal to the mixer 353. The local signal oscillator 352 generates two local signals that are 90 degrees out of phase with each other.

[0078] The transmitted wave receiver 350 performs quadrature detection on the transmitted wave to extract the in-phase component I T and the quadrature component Q T and supplies data indicating the complex amplitude to the control unit 370 as received data.

[0079] The circuits of transmitter 320 and receiver (incident wave receiver 330, etc.) are not limited to the circuits illustrated in the figure, as long as they are capable of transmitting and receiving incident waves, etc.

[0080] [Controller configuration example] 9 is a block diagram showing an example configuration of the control unit 370 according to the first embodiment of the present technology. The control unit 370 includes a transmission control unit 371, a reflection coefficient calculation unit 372, and a transmission coefficient calculation unit 373.

[0081] The transmission control section 371 controls the transmitter 320 to transmit a transmission signal.

[0082] The reflection coefficient calculation unit 372 calculates the reflection coefficient Γ for each frequency. The reflection coefficient calculation unit 372 receives the complex amplitudes of the incident wave and the reflected wave from the incident wave receiver 330 and the reflected wave receiver 340, respectively, and calculates the ratio of these as the reflection coefficient Γ using the following equation. Γ=(I R +jQ R ) / (I I +jQ I )...Equation 1 In the above equation, j is the imaginary unit.

[0083] The reflection coefficient calculation unit 372 calculates the reflection coefficients of N (N is an integer) frequencies f1 to f N The reflection coefficient is calculated for each of these N reflection coefficients Γ1 to Γ2 using Equation 1. N The reflection coefficient calculation unit 372 supplies these reflection coefficients to the communication unit 360.

[0084] The transmission coefficient calculation unit 373 calculates the transmission coefficient T for each frequency. The transmission coefficient calculation unit 373 receives the complex amplitudes of the incident wave and the transmitted wave from the incident wave receiver 330 and the transmitted wave receiver 350, respectively, and calculates the ratio between them as the transmission coefficient T using the following equation. T=(I T +jQ T ) / (I I +jQ I )...Equation 2

[0085] The transmission coefficient calculation unit 373 calculates the N frequencies f1 to f N The transmission coefficient is calculated for each of these N reflection coefficients T1 to T2 using Equation 2. N The transmission coefficient calculation section 373 supplies these transmission coefficients to the signal processing unit 400 via the communication section 360.

[0086] [Example of signal processing unit configuration] 10 is a block diagram showing an example configuration of a signal processing unit 400 according to the first embodiment of the present technology. The signal processing unit 400 includes a communication unit 410, a round-trip delay time calculation unit 420, a propagation transmission time calculation unit 430, a moisture amount measurement unit 440, and a coefficient storage unit 450.

[0087] The communication section 410 receives the measurement data from the measurement unit 300. The communication section 410 receives the reflection coefficients Γ1 to Γ2 in the measurement data. N is supplied to the round trip delay time calculation unit 420, and the transmission coefficients T1 to T N is supplied to the propagation transmission time calculation unit 430.

[0088] The round trip delay time calculation unit 420 calculates the time it takes for an electrical signal to travel back and forth through the cable 308 as a round trip delay time based on the reflection coefficients. N By performing an inverse Fourier transform on Γ Then, the round trip delay time calculation unit 420 calculates the impulse response h Γ The time difference between the peak value timing of (t) and the transmission timing of the CW wave is called the round trip delay time τ 11 and supplied to the moisture content measuring unit 440.

[0089] The propagation / transmission time calculation unit 430 calculates the time it takes for the electromagnetic waves and the electric signals to propagate and transmit through the medium and the cables 308 and 309 based on the transmission coefficients.N By performing an inverse Fourier transform on T Then, the propagation time calculation unit 430 calculates the impulse response h T The time difference between the peak value of (t) and the transmission timing of the CW wave is called the propagation transmission time τ 21 and supplied to the moisture content measuring unit 440.

[0090] The moisture content measurement unit 440 measures the round trip delay time τ 11 and propagation transmission time τ 21 The moisture content measurement unit 440 first calculates the round-trip delay time τ 11 and propagation transmission time τ 21 from propagation delay time τ d Here, the propagation delay time is the time it takes for an electromagnetic wave to propagate through the medium between the probes 201 and 202. The propagation delay time τ d is calculated by the following formula: τ d =τ 21 -τ 11 ...Formula 3 In the above equation, the round trip delay time τ 11 , propagation transmission time τ 21 and propagation delay time τ d The units of each of these are, for example, nanoseconds (ns).

[0091] Then, the moisture amount measurement unit 440 reads out the coefficients a and b that indicate the relationship between the moisture amount and the propagation delay time τd from the coefficient storage unit 450, and calculates the propagation delay time τ d is substituted into the following equation to measure the moisture content x: Then, moisture content measuring section 440 outputs the measured moisture content to an external device or instrument as needed. τ d =a·x+b···Formula 4 In the above formula, the unit of the water content x is, for example, volume percent (%).

[0092] The coefficient holding unit 450 holds the coefficients a and b. A non-volatile memory or the like is used as the coefficient holding unit 450.

[0093] FIG. 11 is a diagram for explaining propagation paths and transmission paths of electromagnetic waves and electric signals in the first embodiment of the present technology.

[0094] As described above, the transmitter 320 transmits an electrical signal including an incident wave as a transmission signal to the probe 201 via the cable 308 whose tip is embedded in the probe 201 .

[0095] The incident wave is reflected at the end of the probe 201, and the reflected wave is received by the reflected wave receiver 340. As a result, an electrical signal including the incident wave and the reflected wave travels back and forth within the cable 308. The thick solid arrow in the figure indicates the route taken by the electrical signal in the cable 308. The time it takes for the electrical signal to travel back and forth along this route is the round trip delay time τ 11 This applies to:

[0096] Furthermore, the electric signal including the incident wave is converted into an electromagnetic wave EW by the probe 201, and passes through (in other words, propagates) the medium between the probes 201 and 202. The probe 202 converts the electromagnetic wave EW into an electric signal. The transmitted wave receiver 350 receives the transmitted wave within the electric signal via the cable 309. That is, the electric signal including the incident wave propagates through the cable 308, is converted into an electromagnetic wave EW, propagates through the medium, is converted into an electric signal including a transmitted wave, and is transmitted through the cable 309. The thick dotted arrows in the figure indicate the paths along which the electromagnetic wave and the electric signal (the incident wave and the transmitted wave) propagate and are transmitted through the medium and the cables 308 and 309. The time it takes for the electromagnetic wave and the electric signal to propagate and be transmitted through this path is called the propagation transmission time τ 21 This applies to:

[0097] The control unit 370 in the measurement unit 300 calculates the reflection coefficient Γ and the transmission coefficient T using Equations 1 and 2. Then, the signal processing unit 400 calculates the round-trip delay time τ 11 and propagation transmission time τ 21 Ask for.

[0098] Here, the path from the transmission of the incident wave to the reception of the transmitted wave includes the medium and the cables 308 and 309. Therefore, the propagation delay time τ d is the propagation transmission time τ 21 and the delay time of the electrical signal traveling through the cables 308 and 309. If it is assumed that the lengths of the cables 308 and 309 are the same, the delay time traveling through the cable 308 will be the same as the delay time traveling through the cable 309. In this case, the total delay time of the electrical signal traveling through the cables 308 and 309 is the round-trip delay time τ 11 Therefore, Equation 3 holds, and the signal processing unit 400 calculates the propagation delay time τ d can be calculated.

[0099] Then, the signal processing unit 400 calculates the calculated round trip delay time τ 11 and propagation transmission time τ 21 and performs processing to measure the amount of moisture contained in the medium from the propagation delay time and the coefficients a and b. Note that the signal processing unit 400 is an example of a processing unit described in the claims.

[0100] 12 is a graph showing an example of a waveform of an impulse response of a reflection coefficient according to the first embodiment of the present technology, in which the vertical axis represents the impulse response of the reflection coefficient and the horizontal axis represents time.

[0101] Assume that four types of Toyoura standard sand with different moisture contents are prepared as media, and the impulse response of the reflection coefficient is obtained by the measuring device 100. The moisture contents of the respective sands are 0.0, 10.1, 19.7, and 32.9 volume percent (%).

[0102] As shown in the figure, even if the moisture content changes, the peak value of the reflection coefficient does not change. In other words, the round trip delay time is constant. This is because, as mentioned above, probes 201 and 202 are separated by outer shell 225.

[0103] 13 is a graph showing an example of the waveform of the impulse response of the transmission coefficient in the first embodiment of the present technology. The vertical axis in the figure represents the impulse response of the transmission coefficient, and the horizontal axis represents time. In the figure, the medium to be measured is the same four types of Toyoura standard sand as in FIG. 12.

[0104] As shown in the figure, the greater the moisture content, the later the timing of the peak value of the transmission coefficient, which results in a longer propagation delay time.

[0105] 14 is a graph showing an example of the relationship between the round-trip delay time and propagation transmission time and the moisture content according to the first embodiment of the present technology, where the vertical axis represents the round-trip delay time or the propagation transmission time, and the horizontal axis represents the moisture content.

[0106] The dotted line in Fig. 14 shows the relationship between the round-trip delay time obtained from Fig. 12 and the moisture content. The solid line in Fig. 14 shows the relationship between the propagation transmission time obtained from Fig. 13 and the moisture content. As shown in Fig. 14, the round-trip delay time is constant regardless of the moisture content. On the other hand, the propagation transmission delay time increases as the moisture content increases.

[0107] 15 is a graph showing an example of the relationship between propagation delay time and moisture content in the first embodiment of the present technology. The vertical axis in the figure represents propagation delay time, and the horizontal axis represents moisture content. The straight line in the figure is obtained by calculating the difference between the propagation transmission time and the round-trip delay time for each moisture content in FIG. 14.

[0108] As shown in Figure 15, the propagation delay time increases as the moisture content increases, and the two are proportional to each other. Therefore, Equation 4 holds true. Coefficient a in Equation 4 is the slope of the line in the figure, and coefficient b is the intercept.

[0109] 16 is a block diagram showing an example configuration of a measurement device according to the first embodiment of the present technology in which the cables 308 and 309 are further extended. By lengthening the cables 308 and 309, the measurement unit 300 and the signal processing unit 400 can be disposed farther away than the probes 201 and 202.

[0110] However, the longer the cables 308 and 309, the greater the fluctuation in the round-trip delay time due to temperature changes. Therefore, if measuring device 100 measures the moisture content using a fixed round-trip delay time, the error between the true value and the fixed value will increase, and the moisture content measurement accuracy may decrease.

[0111] However, measuring device 100 receives the reflected wave and calculates the round-trip delay time from the reflection coefficient. Therefore, even if the round-trip delay time fluctuates due to temperature changes, measuring device 100 can obtain the value at the time of fluctuation. This allows for more accurate moisture content measurement than when the round-trip delay time is a fixed value.

[0112] [Example of measurement device operation] 17 is a flowchart showing an example of the operation of the measurement device 100 according to the first embodiment of the present technology. The operation in the drawing is started, for example, when a predetermined application for measuring moisture content is executed.

[0113] The pair of probes 201 and 202 transmit and receive electromagnetic waves (step S901). The measurement unit 300 calculates a reflection coefficient from the incident wave and the reflected wave (step S902), and calculates a transmission coefficient from the incident wave and the transmitted wave (step S903).

[0114] Next, signal processing unit 400 calculates a round trip delay time from the reflection coefficient (step S904), and calculates a propagation transmission time from the transmission coefficient (step S905). Signal processing unit 400 calculates a propagation delay time from the round trip delay time and the propagation transmission time (step S906), and calculates the moisture content from the propagation delay time and coefficients a and b (step S907). After step S907, measurement device 100 ends the operation for measurement.

[0115] Thus, according to the first embodiment of the present technology, the measuring device 100 calculates the round-trip delay time for the electrical signal to travel back and forth through the cable 308 and measures the moisture content from that round-trip delay time, so that the moisture content can be measured with high accuracy even if the round-trip delay time fluctuates.

[0116] <2. Second embodiment> In the first embodiment described above, the measurement unit 300 and the signal processing unit 400 are mounted on different semiconductor chips. However, this configuration requires an interface for communication between the semiconductor chips, which may increase the circuit size of the measurement device 100. The measurement device 100 of this second embodiment differs from the first embodiment in that the functions of the measurement unit 300 and the signal processing unit 400 are each realized on a single semiconductor chip.

[0117] 18 is a block diagram showing an example configuration of a measurement device 100 according to a second embodiment of the present technology. The measurement device 100 according to the second embodiment differs from the first embodiment in that it includes a measurement unit 301 instead of the measurement unit 300 and the signal processing unit 400.

[0118] The measurement unit 301 has the functions of the signal processing unit 400 in addition to the functions of the measurement unit 300 of the first embodiment.

[0119] 19 is a block diagram showing an example configuration of a measurement unit 301 according to a second embodiment of the present technology. The measurement unit 301 according to the second embodiment differs from the first embodiment in that it includes a signal processing unit 380 instead of the communication unit 360. The configuration of the signal processing unit 380 is similar to that of the signal processing unit 400 according to the first embodiment. In addition, in the same figure, the function of the control unit 370 is realized by, for example, a DSP (Digital Signal Processing) circuit.

[0120] Furthermore, the measurement unit 301 is implemented on a single semiconductor chip. This allows the functions of the measurement unit 300 and the signal processing unit 400 to be realized on a single semiconductor chip. This eliminates the need for an interface (such as the communication unit 360) for communication between semiconductor chips, and allows the circuit scale of the measurement device 100 to be reduced.

[0121] As described above, according to the second embodiment of the present technology, the functions of the measurement unit 300 and the signal processing unit 400 are implemented on a single semiconductor chip, and therefore the circuit size of the measurement device 100 can be reduced compared to when they are implemented on different semiconductor chips.

[0122] <3. Third Embodiment> In the first embodiment described above, the measurement unit 300 and the signal processing unit 400 are connected by a wired connection via a signal line 409. However, this configuration makes it difficult to place the signal processing unit 400 in a remote location away from the measurement location. The measurement unit 300 of this third embodiment differs from the first embodiment in that it transmits measurement data wirelessly.

[0123] 20 is a block diagram showing an example of the configuration of a measurement system according to the third embodiment of the present technology. The measurement system according to the third embodiment includes a sensor device 110 and a signal processing unit 400.

[0124] The sensor device 110 of the third embodiment includes a measurement unit 302 instead of the measurement unit 300. A communication unit 360 of the measurement unit 302 is different from that of the first embodiment in that it wirelessly transmits measurement data to a signal processing unit 400 via an antenna 390.

[0125] The signal processing unit 400 is connected to a base station network or the Internet, and receives measurement data wirelessly transmitted via these networks via wired or wireless connections.

[0126] As shown in the figure, the measurement unit 302 and the signal processing unit 400 are connected wirelessly, so that the signal processing unit 400 can be placed in a remote location away from the measurement location.

[0127] As described above, according to the third embodiment of the present technology, the measurement unit 302 wirelessly transmits measurement data to the signal processing unit 400, so that the signal processing unit 400 can be located in a remote location.

[0128] <4. Fourth embodiment> In the first embodiment described above, the moisture content was measured under the assumption that the delay times for transmitting electrical signals through cables 308 and 309 were the same. However, if cables 308 and 309 were different lengths, the delay times would be different, which could undermine the assumption and result in a measurement error. Measuring device 100 of this fourth embodiment differs from the first embodiment in that it calculates the round-trip delay times for both cables 308 and 309 to measure the moisture content.

[0129] 21 is a block diagram showing an example configuration of a measurement unit 300 according to the fourth embodiment of the present technology. The measurement unit 300 according to the fourth embodiment includes directional couplers 310 and 391, transmitters 320 and 393, incident wave receivers 330 and 394, transmitted wave / reflected wave receivers 392 and 395, a communication unit 360, and a control unit 370.

[0130] The transmitter 320 transmits an incident wave I1 via a cable 308. The transmitter 393 transmits an incident wave I2 via a cable 309. The control unit 370 controls the transmitters 320 and 393 to transmit the incident waves I1 and I2 in sequence.

[0131] The incident wave receiver 330 receives the incident wave I1 when the incident wave I1 is transmitted, and the incident wave receiver 394 receives the incident wave I2 when the incident wave I2 is transmitted.

[0132] The directional coupler 310 separates the electrical signal of the cable 308 into an incident wave and a reflected wave. When an incident wave I1 is transmitted, the directional coupler 310 separates the electrical signal of the cable 308 into the incident wave I1 and a reflected wave R1 corresponding to the incident wave I1. On the other hand, when an incident wave I2 is transmitted, the directional coupler 310 outputs a transmitted wave Tr1 corresponding to the incident wave I2.

[0133] The directional coupler 391 separates the electrical signal of the cable 309 into an incident wave and a reflected wave. When an incident wave I2 is transmitted, the directional coupler 391 separates the electrical signal of the cable 308 into the incident wave I2 and a reflected wave R2 corresponding to the incident wave I2. On the other hand, when an incident wave I1 is transmitted, the directional coupler 391 outputs a transmitted wave Tr2 corresponding to the incident wave I1.

[0134] The transmitted wave / reflected wave receiver 392 receives the transmitted wave and the reflected wave in sequence. When the incident wave I1 is transmitted, the transmitted wave / reflected wave receiver 392 receives the reflected wave R1 from the directional coupler 310, and when the incident wave I2 is transmitted, the transmitted wave Tr1 from the directional coupler 310.

[0135] The transmitted wave / reflected wave receiver 395 receives the transmitted wave and the reflected wave in sequence. When the incident wave I1 is transmitted, the transmitted wave / reflected wave receiver 395 receives the transmitted wave Tr2 from the directional coupler 391, and when the incident wave I2 is transmitted, the transmitted wave / reflected wave receiver 395 receives the reflected wave R2 from the directional coupler 391.

[0136] The incident waves I1 and I2 are examples of the first and second incident waves set forth in the claims, and the reflected waves R1 and R2 are examples of the first and second reflected waves set forth in the claims. The transmitted waves Tr1 and Tr2 are examples of the first and second transmitted waves set forth in the claims. The directional couplers 310 and 391 are examples of the first and second directional couplers set forth in the claims, and the transmitters 320 and 393 are examples of the first and second transmitters. The transmitted wave / reflected wave receivers 392 and 395 are examples of the first and second receivers set forth in the claims.

[0137] The control unit 370 calculates the reflection coefficient Γ from the complex amplitudes of the incident wave I1 and the reflected wave R1 in the same manner as in the first embodiment. 11 The transmission coefficient T is calculated from the complex amplitudes of the incident wave I1 and the transmitted wave Tr2. 21 In addition, the control unit 370 calculates the reflection coefficient Γ from the complex amplitudes of the incident wave I2 and the reflected wave R2 in the same manner as in the first embodiment. 22 Calculate the transmission coefficient T from the complex amplitudes of the incident wave I2 and the transmitted wave Tr1. 12 Calculate.

[0138] The signal processing unit 400 at the subsequent stage calculates the reflection coefficient Γ in the same manner as in the first embodiment. 11 and the transmission coefficient T 12 to the round trip delay time τ 11 and propagation transmission time τ 12 Furthermore, the signal processing unit 400 calculates the reflection coefficient Γ in the same manner as in the first embodiment. 22 and the transmission coefficient T 12 to the round trip delay time τ 22 and propagation transmission time τ 21 Calculate.

[0139] Then, the signal processing unit 400 calculates the propagation delay time τ d Calculate. τ d =(τ 21 +τ12 -τ 11 -τ 22 ) / 2...expression 5

[0140] Next, the signal processing unit 400 calculates the propagation delay time τ d is substituted into Equation 4 to measure the moisture content. 11 and τ 22 are examples of the first and second round trip delay times described in the claims.

[0141] If the lengths of the cables 308 and 309 are different, the delay times of the electrical signals transmitted through the cables may differ. However, even in this case, the round-trip delay time τ 11 In addition to the round trip delay time τ 22 By performing the calculation using the same, it is possible to reduce measurement errors caused by the difference in length between the cables 308 and 309.

[0142] It should be noted that the second and third embodiments can be applied to the fourth embodiment.

[0143] In this way, according to the fourth embodiment of the present technology, the round trip delay time τ corresponding to the cable 308 11 and the round trip delay time τ corresponding to the cable 309 22 Since the moisture content is measured using the cable length measuring device, it is possible to reduce measurement errors caused by differences in the lengths of the cables.

[0144] Note that the above-described embodiment shows an example for realizing the present technology, and the matters in the embodiment and the matters specifying the invention in the claims correspond to each other. Similarly, the matters specifying the invention in the claims and the matters in the embodiment of the present technology having the same name correspond to each other. However, the present technology is not limited to the embodiment, and can be realized by applying various modifications to the embodiment within the scope of the gist thereof.

[0145] The processing procedures described in the above embodiments may be regarded as a method having a series of these procedures, or as a program for causing a computer to execute the series of procedures or a recording medium for storing the program. Examples of recording media that can be used include a CD (Compact Disc), an MD (MiniDisc), a DVD (Digital Versatile Disc), a memory card, and a Blu-ray (registered trademark) Disc.

[0146] The effects described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0147] The present technology can also be configured as follows. (1) a transmitter that transmits an electrical signal including an incident wave to one of a pair of probes, each of which has a cable embedded therein, via the cable; a receiver that receives, via the cable, a reflected wave that is the incident wave reflected by one of the pair of probes and a transmitted wave that is transmitted through a medium between the pair of probes; a processing unit that calculates a round-trip delay time, which is the time it takes for the electric signal to go back and forth through the cable, and measures the amount of moisture contained in the medium based on the round-trip delay time and a propagation / transmission time, which is the time it takes for the electromagnetic wave and the electric signal to propagate and transmit through the medium and the cable; A measuring device comprising: (2) further comprising an outer shell isolating the pair of probes from the medium. The measuring device according to (1) above. (3) The outer shell is made of an electromagnetic wave transmitting material. The measuring device according to (2) above. (4) A spacer is further provided to maintain a constant distance between the pair of probes. The measuring device according to (3) above. (5) The spacer is made of an electromagnetic wave transmitting material. The measuring device according to (4) above. (6) The outer edge of the spacer, which extends between the pair of probes, has an arc shape on the side closer to the antenna portion of each of the pair of probes. The measuring device according to (5) above. (7) The distance from each of the antenna portions of the pair of probes to the lower end of the spacer is greater than the antenna distance, which is the distance between the antenna portions; Preferably, it is greater than twice the distance between the antennas, More preferably, it is greater than three times the distance between the antennas, less than the length of the probe The measuring device according to (6) above. (8) A control unit is further provided which performs control to transmit the incident wave, a process of calculating a ratio of the complex amplitudes of the incident wave and the reflected wave as a reflection coefficient, and a process of calculating a ratio of the complex amplitudes of the incident wave and the transmitted wave as a transmission coefficient, The processing unit calculates the round-trip delay time and the propagation transmission time based on the reflection coefficient and the transmission coefficient. The measuring device according to any one of (1) to (7). (9) The control unit and the processing unit are provided on a predetermined semiconductor chip. The measuring device according to any one of (1) to (8). (10) The control unit is provided on a predetermined semiconductor chip. The processing unit is provided on a semiconductor chip different from the semiconductor chip. The measuring device according to (8) above. (11) Further comprising a communication unit that wirelessly transmits the reflection coefficient and the transmission coefficient to the processing unit. The measuring device according to (8) above. (12) The optical fiber further includes a directional coupler that separates the electrical signal transmitted through the cable into the incident wave and the reflected wave. The measuring device according to any one of (8) to (11) above. (13) The receiver is an incident wave receiver for receiving the incident wave; a reflected wave receiver for receiving the reflected wave; a transmitted wave receiver for receiving the transmitted wave; The measuring device according to (12) above, (14) The incident wave includes a first incident wave and a second incident wave having different directions from each other, the reflected waves include a first reflected wave corresponding to the first incident wave and a second reflected wave corresponding to the second incident wave; the transmitted waves include a second transmitted wave corresponding to the first incident wave and a first transmitted wave corresponding to the second incident wave, the directional coupler includes a first directional coupler that splits the electrical signal into the first incident wave and the first reflected wave, and a second directional coupler that splits the electrical signal into the second incident wave and the second reflected wave; the transmitter includes a first transmitter that transmits the first incident wave and a second transmitter that transmits the second incident wave; The receiver includes a first receiver that sequentially receives the first reflected wave and the first transmitted wave, and a second receiver that sequentially receives the second reflected wave and the second transmitted wave. The measuring device according to (12) above. (15) The round trip delay time includes a first round trip delay time corresponding to one of the pair of probes and a second round trip delay time corresponding to the other of the pair of probes; The processing unit determines the first round-trip delay time from the first incident wave and the first reflected wave, and determines the second round-trip delay time from the second incident wave and the second reflected wave. The measuring device according to (14) above. (16) The processing unit calculates a propagation delay time, which is the time it takes for the electromagnetic wave to propagate through the medium, from the round-trip delay time and the propagation transmission time, and measures the amount of moisture according to the propagation delay time. The measuring device according to any one of (1) to (15) above. (17) The processing unit stores a predetermined coefficient indicating a relationship between the propagation delay time and the moisture content, and measures the moisture content from the calculated propagation delay time and the coefficient. The measuring device according to (16) above. (18) a transmitter that transmits an electrical signal including an incident wave to one of a pair of probes, each of which is connected to a cable, via the cable; a receiver that receives, via the cable, a reflected wave that is the incident wave reflected by one of the pair of probes and a transmitted wave that is transmitted through a medium between the pair of probes; a control unit that performs control to transmit the incident wave and processing to calculate a ratio of the complex amplitudes of the incident wave and the reflected wave as a reflection coefficient; a processing unit that calculates a round-trip delay time, which is the time it takes for the electric signal to go round trip through the cable, from the reflection coefficient, and measures the amount of moisture contained in the medium based on the round-trip delay time and a propagation / transmission time, which is the time it takes for the electromagnetic wave and the electric signal to propagate and transmit through the medium and the cable; A measurement system comprising: (19) a transmitting step of transmitting an electrical signal including an incident wave to one of a pair of probes each having a cable embedded therein, via the cable; a receiving step of receiving, via the cable, a reflected wave obtained by reflecting the incident wave from one of the pair of probes and a transmitted wave that has transmitted through a medium between the pair of probes; a processing procedure for calculating a round-trip delay time, which is the time it takes for the electric signal to travel back and forth through the cable, and measuring the amount of moisture contained in the medium based on the round-trip delay time and a propagation / transmission time, which is the time it takes for the electromagnetic wave and the electric signal to propagate and transmit through the medium and the cable; A measuring method comprising: [Explanation of symbols]

[0148] 100 Measuring Device 110 Sensor device 200 sensor head 201, 202 probes 210 Antenna section 211 Core section 212 Shield section 213 Electrode section 225 Outer Shell 240 Electromagnetic wave absorbing material 260 Spacer 300, 301, 302 measuring units 308, 309 Cable 310, 391 Directional coupler 311, 312, 313 Transmission lines 314, 315 Termination resistor 320, 393 transmitter 321 Driver 322 Transmit Signal Oscillator 330, 394 Incident wave receiver 331, 341, 353 Mixer 332, 342, 354 bandpass filters 333, 343, 355 Analog-to-Digital Converters 340 Reflected Wave Receiver 350 Through-wave receiver 351 Receiver 352 Local Signal Oscillator 360, 410 Communications Department 370 Control Unit 371 Transmission control section 372 Reflection coefficient calculation unit 373 Transmission coefficient calculation section 380 Signal Processing Unit 390 Antenna 392, 395 Transmitted wave and reflected wave receiver 400 Signal Processing Unit 420 Round-trip delay time calculation unit 430 Propagation transmission time calculation unit 440 Moisture measurement unit 450 Coefficient storage unit

Claims

1. a transmitter that transmits an electrical signal including an incident wave via a cable to one of a pair of probes, each of which has a cable embedded therein; a receiver that receives, via the cable, a reflected wave that is the incident wave reflected by one of the pair of probes and a transmitted wave that is transmitted through a medium between the pair of probes; a communication unit that transmits measurement data generated by the receiver to a processing unit that calculates a round-trip delay time, which is the time it takes for the electrical signal to travel back and forth through the cable, and measures the amount of moisture contained in the medium based on the round-trip delay time and a propagation / transmission time, which is the time it takes for the electromagnetic wave and the electrical signal to propagate and transmit through the medium and the cable; an outer shell covering each of the pair of probes; Equipped with The outer shell has a pointed tip, a spacer for maintaining a constant distance between the pair of probes; The thickness of the spacer is smaller than the thickness of at least one of the pair of probes. Measuring equipment.

2. The outer shell is made of an electromagnetic wave transmitting material. The measuring device according to claim 1.

3. The spacer is made of an electromagnetic wave transmitting material. The measuring device according to claim 1.

4. The outer edge of the spacer, which extends between the pair of probes, has an arc shape on the side closer to the antenna portion of each of the pair of probes. The measuring device according to claim 3.

5. a distance from each of the antenna portions of the pair of probes to a lower end of the spacer is greater than an antenna distance between the antenna portions, less than the length of the probe 5. The measuring device according to claim 4.

6. a distance from each of the antenna portions of the pair of probes to a lower end of the spacer is greater than twice the inter-antenna distance, which is the distance between the antenna portions; less than the length of the probe 5. The measuring device according to claim 4.

7. a distance from each of the antenna portions of the pair of probes to a lower end of the spacer is greater than three times the inter-antenna distance, which is the distance between the antenna portions; less than the length of the probe 5. The measuring device according to claim 4.

8. a control unit that performs control to transmit the incident wave, a process to calculate a ratio of the complex amplitudes of the incident wave and the reflected wave as a reflection coefficient, and a process to calculate a ratio of the complex amplitudes of the incident wave and the transmitted wave as a transmission coefficient, The processing unit calculates the round-trip delay time and the propagation transmission time based on the reflection coefficient and the transmission coefficient. The measuring device according to claim 1.

9. The control unit and the processing unit are provided on a predetermined semiconductor chip.

9. The measuring device according to claim 8.

10. The control unit is provided on a predetermined semiconductor chip. The processing unit is provided on a semiconductor chip different from the semiconductor chip.

9. The measuring device according to claim 8.

11. The optical fiber further includes a directional coupler that separates the electrical signal transmitted through the cable into the incident wave and the reflected wave.

9. The measuring device according to claim 8.

12. The receiver includes: an incident wave receiver for receiving the incident wave; a reflected wave receiver for receiving the reflected wave; a transmitted wave receiver for receiving the transmitted wave. The measuring device according to claim 11.

13. the incident waves include a first incident wave and a second incident wave having different directions from each other; the reflected waves include a first reflected wave corresponding to the first incident wave and a second reflected wave corresponding to the second incident wave; the transmitted waves include a second transmitted wave corresponding to the first incident wave and a first transmitted wave corresponding to the second incident wave, the directional coupler includes a first directional coupler that splits the electrical signal into the first incident wave and the first reflected wave, and a second directional coupler that splits the electrical signal into the second incident wave and the second reflected wave; the transmitter includes a first transmitter that transmits the first incident wave and a second transmitter that transmits the second incident wave; The receiver includes a first receiver that sequentially receives the first reflected wave and the first transmitted wave, and a second receiver that sequentially receives the second reflected wave and the second transmitted wave. The measuring device according to claim 11.

14. the incident waves include a first incident wave and a second incident wave having different directions from each other; the reflected waves include a first reflected wave corresponding to the first incident wave and a second reflected wave corresponding to the second incident wave; the round trip delay times include a first round trip delay time corresponding to one of the pair of probes and a second round trip delay time corresponding to the other of the pair of probes; The processing unit determines the first round-trip delay time from the first incident wave and the first reflected wave, and determines the second round-trip delay time from the second incident wave and the second reflected wave. The measuring device according to claim 11.

15. The processing unit calculates a propagation delay time, which is the time it takes for the electromagnetic wave to propagate through the medium, from the round-trip delay time and the propagation transmission time, and measures the amount of moisture according to the propagation delay time. The measuring device according to claim 1.

16. The processing unit stores a predetermined coefficient indicating a relationship between the propagation delay time and the moisture content, and measures the moisture content from the propagation delay time and the coefficient.

16. The measuring device according to claim 15.

17. a transmitter that transmits an electrical signal including an incident wave via a cable to one of a pair of probes, each of which is connected to a cable; a receiver that receives, via the cable, a reflected wave that is the incident wave reflected by one of the pair of probes and a transmitted wave that is transmitted through a medium between the pair of probes; a control unit that performs control to transmit the incident wave and processing to calculate a ratio of the complex amplitudes of the incident wave and the reflected wave as a reflection coefficient; a communication unit that transmits measurement data generated by the receiver to a processing unit that calculates a round-trip delay time, which is the time it takes for the electrical signal to travel back and forth through the cable, from the reflection coefficient, and measures the amount of moisture contained in the medium based on the round-trip delay time and a propagation / transmission time, which is the time it takes for the electromagnetic wave and the electrical signal to propagate and transmit through the medium and the cable; an outer shell covering each of the pair of probes; Equipped with The outer shell has a pointed tip, a spacer for maintaining a constant distance between the pair of probes; The thickness of the spacer is smaller than the thickness of at least one of the pair of probes. Measurement system.

18. a transmitter that transmits an electrical signal including an incident wave via a cable to one of a pair of probes, each of which is connected to a cable; a receiver that receives, via the cable, a reflected wave that is the incident wave reflected by one of the pair of probes and a transmitted wave that is transmitted through a medium between the pair of probes; a communication unit that transmits the measurement data generated by the receiver to a processing device that calculates a round-trip delay time, which is the time it takes for the electrical signal to travel back and forth through the cable, from a reflection coefficient that is the ratio of the complex amplitudes of the incident wave and the reflected wave, and measures the amount of moisture contained in the medium based on the round-trip delay time and a propagation / transmission time, which is the time it takes for the electromagnetic wave and the electrical signal to propagate and transmit through the medium and the cable; and a directional coupler that separates the electrical signal transmitted through the cable into the incident wave and the reflected wave; an outer shell covering each of the pair of probes; Equipped with The receiver includes: an incident wave receiver for receiving the incident wave; a reflected wave receiver for receiving the reflected wave; a transmitted wave receiver for receiving the transmitted wave; one of the pair of probes includes a first antenna unit that converts the electrical signal including the incident wave into the electromagnetic wave; the other of the pair of probes includes a second antenna unit that converts the electromagnetic wave into the electrical signal including the transmitted wave; the measurement data is data indicating a reflection coefficient obtained based on an output of the incident wave receiver and an output of the reflected wave receiver, and a transmission coefficient calculated based on an output of the incident wave receiver and an output of the transmitted wave receiver, The outer shell has a pointed tip, a spacer for maintaining a constant distance between the pair of probes; The thickness of the spacer is smaller than the thickness of at least one of the pair of probes. Measurement system.

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