CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 U.S.C. 371 and claims the benefit of PCT Application No. PCT/JP2018/016007 having an international filing date of 18 Apr. 2018, which designated the United States, which PCT application claimed the benefit of Japanese Patent Application No. 2017-109917 filed 2 Jun. 2017, the entire disclosures of each of which are incorporated herein by reference.

TECHNICAL FIELD

The present technology relates to a sensor device, a water amount measurement device, a water amount measurement method, an information processing device, and an information processing method that are used for measuring a water amount in a medium such as soil.

BACKGROUND ART

Time-domain reflectometry (TDR) is known as a method for measuring a water amount in a medium. This method includes transmitting an electromagnetic wave along a metallic probe embedded in a medium, and calculating a water amount in the medium from relative permittivity measured using its reflection response (for example, refer to Patent Literature 1).

CITATION LIST

Patent Literature

Patent Literature 1: Japanese PatentApplication Laid-open No. H10-90201

DISCLOSURE OF INVENTION

Technical Problem

However, there is a problem in which, since the TDR measures relative permittivity using the characteristics of a propagation of an electromagnetic wave in the vicinity of a probe in a medium, a gap produced in the vicinity of the probe has a great impact on the measurement, and thus it is not possible to measure relative permittivity correctly.

In view of the circumstances described above, it is an object of the present technology to provide a sensor device, a water amount measurement device, a water amount measurement method, an information processing device, and an information processing method that make it possible to improve accuracy in the measurement of relative permittivity of a medium or a water amount in the medium.

Solution to Problem

A sensor device according to an embodiment of the present technology includes a sensor head and a measurement unit.

The sensor head includes a first probe and a second probe, the first probe including a first antenna section used for transmission, the second probe including a second antenna section used for reception, the second probe being situated at a specified distance from the first probe and facing the first probe.

The measurement unit includes a signal generator that generates a measurement signal that includes information regarding characteristics of a propagation of an electromagnetic wave in a medium between the first and second antenna sections.

The sensor device obtains the characteristics of a propagation of an electromagnetic wave in a medium between the first probe and the second probe that respectively perform transmission and reception of an electromagnetic wave. The impact that a gap produced in the vicinity of each probe has on the measurement of relative permittivity or a water amount, can be made small sufficiently to ignore, by making a distance between the first and second probes sufficiently larger than the gap.

The sensor device transmits and receives an electromagnetic wave through the first and second antenna sections, and this prevents the measurement accuracy from being decreased due to resonances of the probes.

The first and second probes may be each constituted of a coaxial cable that includes a core wire portion and a shield portion. In this case, the first and second antenna sections may be each configured as a hole provided in a portion of the shield portion.

This makes it possible to obtain a simple configuration of a probe including an antenna section.

The first and second probes may each include an end resistance that is electrically connected between an end of the core wire portion and the shield portion.

This prevents undesired reflections of a transmission signal and a reception signal at the ends of probes.

The sensor head may further include an electromagnetic wave absorption material. The electromagnetic wave absorption material is provided in each of the first and second probes to cover a portion around the hole in the shield portion.

This prevents a transmission signal and a reception signal from being leaked from a region other than the hole.

The electromagnetic wave absorption material may include ferrite.

The sensor head may further include a support substrate that includes a first arm, a second arm, and a coupling portion that couples the first arm to the second arm, and the first and second probes may be respectively constituted of striplines respectively provided in the first and second arms. This makes it possible to obtain a simple and tough configuration of the sensor head, and to improve the handleability.

In this case, the measurement unit may be mounted on the coupling portion.

This enables the sensor head and the measurement unit to be integral with each other.

The sensor head may further include a temperature detector. The temperature detector is provided in at least one of the first probe or the second probe and is capable of detecting a temperature of the medium.

This makes it possible to obtain information regarding a temperature of a medium that is used to correct measurement data.

The sensor head may further include an electric conductivity detector. The electric conductivity detector is provided in at least one of the first probe or the second probe and is capable of detecting electric conductivity of the medium.

This makes it possible to obtain information regarding electric conductivity of a medium that is used to correct measurement data.

The signal generator may include a signal creating section and a quadrature detector. The signal creating section inputs a pulse signal of a specified frequency to the first probe. The quadrature detector performs quadrature detection on an output from the second probe.

This makes it possible to generate information regarding a propagation delay time of an electromagnetic wave that propagates between probes.

The measurement unit may further include a communication section that is capable of transmitting the measurement signal to an information processing device.

This makes it possible to provide the measurement signal to the information processing device arranged in a location different from an observation point.

A water amount measurement device according to an embodiment of the present technology includes a sensor head, a measurement unit, and a signal processing section.

The sensor head includes a first probe and a second probe, the first probe including a first antenna section used for transmission, the second probe including a second antenna section used for reception, the second probe being situated at a specified distance from the first probe and facing the first probe.

The measurement unit generates a measurement signal that includes information regarding characteristics of a propagation of an electromagnetic wave in a medium between the first and second antenna sections.

The signal processing section measures a water amount in the medium using the measurement signal.

The signal processing section may include a delay time calculator, a relative permittivity calculator, and a water amount calculator. The delay time calculator calculates a propagation delay time of an electromagnetic wave between the first and second probes using the measurement signal. The relative permittivity calculator calculates relative permittivity of a medium using the propagation delay time. The water amount calculator calculates a water amount in the medium using the relative permittivity.

The sensor head may further include a temperature detector that is capable of detecting a temperature of the medium, and the signal processing section may be configured to correct the water amount according to an output from the temperature detector.

The sensor head may further include an electric conductivity detector that is capable of detecting electric conductivity of the medium, and the signal processing section may be configured to correct the water amount according to an output from the electric conductivity detector.

A water amount measurement method according to an embodiment of the present technology includes receiving, by a second antenna section of a second probe, an electromagnetic wave transmitted from a first antenna section of a first probe arranged in a medium, and generating a measurement signal that includes information regarding characteristics of a propagation of the electromagnetic wave, the second probe being arranged in the medium to be situated at a specified distance from the first probe. A water amount in the medium is measured using the measurement signal.

The measuring the water amount may include calculating a propagation delay time of the electromagnetic wave that is measured using the measurement signal, calculating relative permittivity of the medium using the propagation delay time, and calculating a water amount in the medium using the relative permittivity.

The medium may be soil.

An information processing device according to an embodiment of the present technology includes a delay time calculator, a relative permittivity calculator, and a water amount calculator.

The delay time calculator calculates a propagation delay time of an electromagnetic wave between a first probe and a second probe using an electromagnetic wave transmitted from a first antenna section of the first probe and received by a second antenna section of the second probe, the first probe being arranged in a medium, the second probe being arranged in the medium to be situated at a specified distance from the first probe.

The relative permittivity calculator calculates relative permittivity of the medium using the propagation delay time.

The water amount calculator calculates a water amount in the medium using the relative permittivity.

An information processing method according to an embodiment of the present technology includes calculating a propagation delay time of an electromagnetic wave between a first probe and a second probe using an electromagnetic wave transmitted from a first antenna section of the first probe and received by a second antenna section of the second probe, the first probe being arranged in a medium, the second probe being arranged in the medium to be situated at a specified distance from the first probe.

Relative permittivity of the medium is calculated using the propagation delay time.

A water amount in the medium is calculated using the relative permittivity.

Advantageous Effects of Invention

As described above, the present technology makes it possible to improve accuracy in the measurement of relative permittivity of a medium or a water amount in the medium.

Note that the effect described here is not necessarily limitative and may be any effect described in the present disclosure.

