JP4943391B2 - Wireless relay device - Google Patents

Description

    The present invention relates to a wireless relay device, and more particularly, to a wireless relay device used when wireless communication is performed between a wireless device installed underground in a place where a manhole cover is installed and a wireless device installed on the ground.

    In the basement (underground), various underground objects such as water and sewage troughs, gas pipes, power cables, and optical fiber cables are laid. These underground objects are configured to be monitored for conditions such as whether or not they normally operate. For example, Patent Document 1 shows an example in which the state of a branch pipe having a fire hydrant in which an underground buried object is buried in the ground is monitored. That is, a wireless measuring device that measures water pressure, water quality, flow rate, and the like is provided at the end of the branch pipe, and radio waves (signals) including measurement data transmitted from the antenna of the measuring device are made of cast iron. It is configured to be received by a base station installed on the ground via a manhole cover. Therefore, on the ground side, it is possible to monitor the state of the branch pipe laid underground without an operator entering the manhole. The cast iron manhole cover of Patent Document 1 is configured to be connected to the cover receiving portion via an electrically insulating member. As a result, the manhole cover is not at the same potential as the lid receiving portion, and the shielding effect of radio waves on the manhole cover is reduced, so that wireless communication between a radio installed in the basement and a base station installed on the ground can be performed. It can be carried out.

  Regarding wireless communication between the underground and the ground via a cast iron manhole cover, in addition to Patent Document 1, the manhole cover itself is operated as an antenna, and a slot antenna is provided in a keyhole provided in the manhole cover. One that is installed and operates as an antenna, One that installs an antenna near the hole on the back of the manhole cover, radiates electromagnetic waves to the ground, and uses it for wireless connection In addition, a reflector that is installed at a branch point in a manhole and used for wireless connection with the ground has been proposed.

Non-Patent Document 1 discloses a wireless relay device that does not use a manhole cover. That is, here, a wireless relay device is disclosed that is configured to perform radio communication by allowing radio waves to pass through an asphalt or concrete pavement provided around a manhole cover.
FIG. 6 is a cross-sectional view showing a schematic configuration of a manhole portion to which this wireless relay device is applied. Further explanation will be made with reference to FIG. 6. A water pipe 21 is embedded in the soil 20, and A branch pipe 22 is branched from a part of the water pipe 21. In addition, a manhole 23 made of concrete and having a sufficient space inside is embedded in the branch pipe 22 so as to surround the upper portion of the branch pipe 22. A cast iron manhole cover 24 is provided above the manhole 23. As shown in the enlarged upper part of FIG. 6, the manhole 24 has a cast iron frame 24a in which the surface position of the concrete layer 25 constituting the ground surface coincides with the upper surface, and is attached to and detached from the frame 24a. It is comprised from the lid 24b made from cast iron provided freely.

  In FIG. 6, reference numeral 26 denotes an air valve provided at the tip of the branch pipe 22 in the manhole 23. A sensor for detecting various data such as water pressure and flow velocity is not shown at the position of the air valve. A group is provided. The radio waves including data detected by these sensor groups are configured to be transmitted toward the ground space via the underground radio device 27 provided in the manhole 23. This underground radio apparatus 27 is provided with a rod-like λ / 4 antenna 27a (λ; wavelength) whose longitudinal direction is directed toward the center of the lid 24b, and a lower portion of the λ / 4 antenna 27a. Reflector 27b that suppresses the primary radiation toward soil 20 and increases the radiation power directed upward, radio device main body case 27c, and data detected by the sensor group are processed and a signal is transmitted to radio device main body case 27c. And a processing device 27d.

Radio waves are transmitted from the underground radio device 27 toward the ground surface. The transmitted radio wave radiation characteristics are the geometric structure of underground structures such as the manhole 23, the structure of the λ / 4 antenna 27a, It depends on the arrangement position and direction, the frequency (wavelength) of the radio wave used, the nature of the soil 20, the dielectric properties of the concrete layer (asphalt layer) 25 and the like. When a ground radio device (not shown in FIG. 6) is placed on the surface of the concrete layer 25, that is, a predetermined position on the ground around the manhole cover 24, radio waves from the underground radio device 27 are received. can do.
JP-A-11-61867 Mizuna Shizuo, Adachi Akira, Watanabe Nao, "Radiation from 430MHz antenna in manhole", Proceedings of 2007 General Conference BS-5-4, IEICE, March 7, 2007, p. S-33 to S-34

However, the wireless relay device using the conventional manhole cover shown in Patent Document 1 needs to add an electric insulation structure to the manhole cover, and has a drawback that the structure is complicated and is transmitted to the ground surface side. There was a drawback that the radio signal level was low.
In addition, other wireless relay devices using a conventional manhole cover have design problems such as the need to match the impedance of the antenna when the manhole cover is used as an antenna, and a manhole inner cover is required. When the feeding point and the feeding cable are provided near the back of the manhole cover, the cable may be damaged by opening and closing the manhole cover, and the slot antenna is attached to the keyhole of the manhole cover Not only does the opening / closing operation of the manhole cover become complicated, but it also requires a connection cable to the slot antenna, and when the keyhole is small, there is a drawback that the amount of attenuation due to electromagnetic wave blocking becomes large. When installing the unit, complicated processing such as drilling holes in the manhole cover is required. There was that drawback.
Further, in the wireless relay device that does not use the manhole cover described in Non-Patent Document 1, the radio wave radiated from the λ / 4 antenna 27a is reflected by the manhole cover 24 and has a complicated electromagnetic field distribution in the space in the manhole 23. In order to make it, it is necessary to perform a complicated three-dimensional electromagnetic field numerical analysis to predict the radiation characteristics, and there is a drawback that the radio signal level transmitted to the ground surface is low.

    Therefore, the present invention has been made to eliminate the above-described drawbacks, and the purpose of the present invention is to provide a radio installed in the basement without a manhole cover at a place where the manhole cover is installed and a radio installed on the ground. An object of the present invention is to provide a wireless relay device that can perform wireless communication with a machine and can increase the level of a wireless signal transmitted to the ground surface.

In order to achieve the above object, a wireless relay device according to the present invention is used when wireless communication is performed between a wireless device installed underground in a place where a manhole cover is installed and a wireless device installed on the ground. The relay device includes a reflector that reflects radio waves radiated from the wireless device toward the back side of the manhole cover toward a predetermined position on the ground surface around the manhole cover.
In the wireless relay device having the above configuration, the radio wave irradiated toward the back side of the manhole cover is reflected by the reflector and is a predetermined position on the ground surface around the manhole cover, that is, a specific position on the ground surface around the manhole cover Irradiated towards. When radio waves are emitted from a specific position on the surface of the earth toward the ground, the radio waves are reflected by a reflector and received by a radio set in the basement.

Further, the wireless relay device according to the present invention is characterized in that the reflector is provided with an attachment angle adjusting mechanism for arbitrarily changing the reflection direction of the radio wave emitted from the wireless device.
In the wireless relay device having the above configuration, the reflector can arbitrarily change the reflection direction of the radio wave by the attachment angle adjusting mechanism, and the radio wave is directed in a desired direction.
Furthermore, the wireless relay device according to the present invention is characterized in that the surface shape for receiving the radio wave irradiated from the reflector wireless device is formed flat.
The wireless relay device according to the present invention is characterized in that the surface shape of the reflector that receives the radio wave irradiated from the wireless device has a concave shape.
Moreover, the wireless relay device according to the present invention is characterized in that the reflector is constituted by a grid.
Furthermore, the wireless relay device according to the present invention is characterized in that the reflector is made of a mesh such as a perforated plate.
The wireless relay device according to the present invention is characterized in that the reflector is made of metal.
In the wireless relay device according to the present invention, the reflector is configured by covering a base made of synthetic resin with a material that reflects radio waves.

The radio relay device according to the present invention directs radio waves radiated from the radio toward the back side of the manhole cover toward a predetermined position on the ground surface around the manhole cover, that is, a specific position on the ground surface around the manhole cover. Since it has a reflector to reflect, wireless communication can be performed between a wireless device installed underground and a wireless device installed on the ground without using a manhole cover. This makes it easy to handle the manhole cover, does not require complicated processing such as drilling holes in the manhole cover, and does not impair the robustness of the manhole cover. can do. Furthermore, since the radio waves irradiated toward the specific position on the ground surface can be collected by the reflector, the radio signal level transmitted to the ground surface side can be increased.
Moreover, since the attachment angle adjusting mechanism is provided in the reflector, the wireless relay device according to the present invention can easily reflect toward a specific position on the ground surface around the manhole cover.
In the wireless relay device according to the present invention, the reflector has a flat or concave surface shape, the reflector is made of a grid or a mesh, and the reflector is made of a metal or a synthetic resin base. Since it can be configured by coating a material that reflects radio waves, a reflector can be easily obtained.

The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of a manhole portion to which a radio relay apparatus according to an embodiment of the present invention is applied, and FIG. 2 is an enlarged cross-sectional view taken along line X ₁ -X ₁ in FIG.

  In the figure, reference numeral 1 denotes a concrete manhole embedded in the soil 2, and a sufficient space in which an operator can work is provided. The bottom of the manhole 1 is opposed to a part of a predetermined underground object (not shown) such as a water pipe. And the manhole cover 3 is provided in the upper part so that attachment or detachment is possible. Although this manhole cover 3 is not shown in the figure, as in FIG. 6 described above, a cast iron frame body in which the surface position of the asphalt layer (which may be a concrete layer) 4 constituting the ground surface coincides with the upper surface position; It is comprised from the cover body provided in the frame body so that attachment or detachment was possible. In the example shown in the drawing, the planar shape of the manhole cover 3 is circular, but the manhole cover may be a rectangular shape.

  In the figure, reference numeral 5 denotes a wireless device installed in the manhole 1, that is, in the basement, and directs radio waves including various data acquired from underground objects via a reflector, which will be described later, toward the ground, that is, the manhole 1. It is comprised so that it can send out toward the back surface side of the manhole cover 3 provided in the upper part side. The wireless device 5 includes a function of processing various data detected from the underground object via a sensor (not shown) and a function of transmitting the processed data to the outside by wireless communication. For example, when the underground buried object is a water pipe as in FIG. 6 described above, the wireless device 5 is configured to be able to send radio waves including various data such as water pressure and flow velocity toward the ground.

The radio wave used in the wireless device 5 is UHF (ultra-high frequency) having a frequency of 300 MHz to 3 GHz, and even if the material around the manhole cover 3 is the asphalt layer 4 (or concrete layer), the asphalt layer 4 There is a feature that wireless communication can be easily performed through the network. This is because the radio wave absorption rate of asphalt or concrete in this frequency band is lower than that of soil. If the material is asphalt, wireless communication can be performed without any problem even if the thickness is 10 cm to 30 cm. Is possible. Even if the material around the manhole cover 3 is soil, radio communication can be performed because radio waves are collected by a reflector described later.
As described above, in the wireless relay device of the present invention, the reflector 10a and the wireless device, which will be described later, so that the radio waves can actively pass through the radio wave transmitting structural material such as asphalt and concrete around the manhole cover 3. Is arranged.

  As indicated by broken line arrows in FIG. 1, the wireless device 5 is configured not only to transmit radio waves from the underground toward the ground but also to receive radio waves from the ground. Of course, the wireless device 5 may be a one-way type that transmits radio waves only from the underground toward the ground. As shown in the figure, when the wireless device 5 is a two-way type, there is a feature that data of underground objects can be transmitted to the ground according to a data request signal from the ground side.

  In the figure, reference numeral 10a denotes a reflector that forms a part of the main body of the wireless relay device of the present invention, the planar shape is a rectangular metal plate, and the surface that receives radio waves emitted from the wireless device 5 is flat. It is configured. The reflector 10 a is attached to the lower end side of the support rod 11 whose upper end side is fixed to the back surface of the manhole cover 3 via the attachment angle adjusting mechanism 12. The size of the surface of the reflector 10a that receives radio waves is determined so that the radio waves emitted from the wireless device 5 can be efficiently reflected. That is, the length of one side of the reflector 10a is determined to be ½ or more, preferably 3 to 5 wavelengths of the radio wave used. The reflector 10a passes through a part of the asphalt layer 4 around the manhole cover 3 and does not collide with the manhole cover 3 when the radio wave emitted from the radio device 5 collides with the manhole cover 3. As shown (see the broken line arrow in FIG. 1), it is attached to the support bar 11 with a predetermined angle. At a predetermined position on the surface of the asphalt layer 4 through which radio waves pass, that is, a specific position P on the surface of the ground, a predetermined mark indicating a position suitable for communication with the radio device 5 installed underground is provided.

  The specific position on the ground surface is set as close as possible to the manhole cover 3 in order to shorten the passing distance of radio waves in the asphalt layer 4. The setting of the specific position P can be easily performed by adjusting the mounting angle of the reflector 10a via the mounting angle adjusting mechanism 12. That is, the attachment angle adjustment mechanism 12 is configured in the same manner as a known attachment angle adjustment mechanism. For example, the attachment angle adjusting mechanism 12 is provided with a sphere on one attachment portion between the attachment portion on the lower end side of the support bar 11 and the attachment portion of the reflector 10a, and the sphere can be moved on the other attachment portion. It can be configured by providing a sandwiching portion that surrounds.

  In FIG. 1, the reflector 10 a is attached to a support bar 11 fixed to the manhole cover 3. It can also be attached to the inner wall. In this case, since the installation position of the support bar 11 is fixed, the feature that the specific position P on the ground surface does not change can be obtained.

  When wireless communication is performed between the wireless device 5 installed underground and a wireless device (not shown) installed on the ground using the wireless relay device having the above-described configuration, the antenna of the ground wireless device is the above-mentioned ground surface. Is placed at a specific position P. In this specific position P, since the radio waves are concentrated by the reflector 10a, the radio signal level transmitted to the ground surface is high, and wireless communication from the ground to the ground can be performed with high accuracy, and from the ground to the ground. Wireless communication can be performed with high accuracy.

  Since the wireless relay device having the above-described configuration includes the reflector 10a, not only can radio waves be concentrated and highly accurate wireless communication can be performed, but also the wireless device 5 installed in the basement without the manhole cover 3 and Since wireless communication can be performed with a radio installed on the ground, the manhole cover 3 can be easily handled, and complicated processing such as making a hole in the manhole cover 3 is not required. The wireless relay device can be easily designed and constructed without impairing the robustness of 3. In addition, since the wireless relay device having the above-described configuration is provided with the attachment angle adjusting mechanism 12 in the reflector 10a, the specific position P can be set at an arbitrary position on the ground surface around the manhole cover 3.

  The reflector 10b shown in FIGS. 3 (a) and 3 (b) is a reflector having another shape, and the surface receiving the radio wave is formed in a concave shape. That is, the reflector 10b is made of metal and is formed in a parabolic antenna type. Since the reflector 10b has a concave surface for receiving radio waves, the effect of collecting radio waves with respect to the specific position P can be further enhanced.

  The reflector 10c shown in FIGS. 4 (a) and 4 (b) is a reflector having another shape. The reflector 10c is composed of a metal grid having a rectangular planar shape, and the surface receiving the radio wave emitted from the wireless device 5 is flat. The pitch of the grid is determined to be one tenth or less of the radio wave used, and the reflection loss of the radio wave is suppressed. Since the reflector 10c has a grid configuration, it has a feature that the reflector can be reduced in weight. The reflector 10c having this grid configuration can be a parabolic antenna type similar to that shown in FIGS. 3 (a) and 3 (b).

  The reflector 10d shown in FIGS. 5A and 5B is a reflector having another shape. The reflector 10d is composed of a mesh of a metal perforated plate having a rectangular planar shape, and the surface that receives radio waves emitted from the wireless device 5 is flat. One side of the mesh is determined to be one-tenth or less of the radio wave used, and the reflection loss of the radio wave is suppressed. Since the reflector 10d has a mesh configuration, it has a feature that can reduce the weight of the reflector. The reflector 10d having this mesh configuration can be a parabolic antenna type similar to that shown in FIGS. 3 (a) and 3 (b).

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above-described embodiment, and a design change or the like is possible without departing from the gist of the present invention. It is.
For example, in the above example, the reflectors 10a, 10b, 10c, and 10d are made of metal, but the base of the reflector is made of synthetic resin, and a material that reflects radio waves is coated on the base by plating or vapor deposition. May be. In this case, a lighter reflector can be obtained at a low cost.
In the above example, the flat reflector 10a is used as the flat reflector, but the planar shape is not limited to this, and the planar shape is not circular, elliptical, or quadrangular. A polygonal reflector (triangular, pentagonal, etc.) may be used.
Further, in the above-described example, the reflector 10b having a concave surface for receiving radio waves and a circular shape in plan view is used. However, the present invention is not limited thereto, and the surface for receiving radio waves is concave and the plan view is elliptical. Or polygonal (triangular, quadrangular, pentagonal, etc.) reflectors may be used.
In the above-described example, the manhole 1 is a large-sized example in which an operator enters and exits. However, the manhole 1 may be a so-called handhole in which only the operator's hand enters and exits. Therefore, in the present invention, the term “manhole” includes such a type that a worker does not go in and out.
Furthermore, in the above-described example, the material around the manhole cover 3 is the asphalt layer 4 or the concrete layer, but the periphery of the manhole cover 3 may be a dielectric material such as rubber or synthetic resin. For example, the periphery of the manhole cover 3 may be covered with rubber as a buffer material, and even in this case, radio waves can be passed efficiently.

It is sectional drawing which shows schematic structure of the manhole part to which the radio relay apparatus which concerns on one embodiment of this invention is applied. It is X ₁ -X ₁ line enlarged cross section of FIG. 1. (A) is a perspective view when a surface shaped to receive a radio wave reflector in a concave shape, a X ₂ -X ₂ line cross-sectional view of (b) is (a). (A) is a front view when constituting the reflector with the grid, an X ₃ -X ₃ line cross-sectional view of (b) is (a). (A) is a front view when constituting the reflector mesh, a X ₄ -X ₄ line cross-sectional view of (b) is (a). It is sectional drawing which shows schematic structure of the manhole part to which the conventional radio relay apparatus is applied.

Explanation of symbols

1 ... Manhole, 2 ... Underground, 3 ... Manhole cover, 4 ... Concrete layer, 5 ... Radio, 10a, 10b, 10c, 10d ... Reflector, 11 ... Support rod, 12 ... Mounting angle adjustment mechanism, P ... Specific position (predetermined position on the ground surface)

Claims (8)

A wireless relay device used when wirelessly communicating between a radio installed underground and a radio installed on the ground at a manhole cover installation location,
A radio relay apparatus comprising: a reflector that reflects radio waves radiated from the radio toward the back side of the manhole cover toward a predetermined position on the ground surface around the manhole cover.   The wireless relay device according to claim 1, wherein the reflector is provided with an attachment angle adjustment mechanism that arbitrarily changes a reflection direction of a radio wave emitted from the wireless device.   The wireless relay device according to claim 1, wherein a surface shape of the reflector that receives radio waves emitted from the wireless device is flat.   The wireless relay device according to claim 1 or 2, wherein a surface shape of the reflector that receives radio waves emitted from the wireless device is concave.   The wireless relay device according to claim 1, wherein the reflector is configured by a grid.   The wireless relay device according to claim 1, wherein the reflector is made of a mesh.   The wireless relay device according to claim 1, wherein the reflector is made of metal.   The wireless relay device according to claim 1, wherein the reflector is configured by covering a base made of synthetic resin with a material that reflects radio waves.

Images