JP5398637B2 - Wireless communication system - Google Patents

Description

  The present invention receives the information (ID and the situation in the manhole) transmitted from the wireless tag installed in the manhole with the reader on the ground, and the situation inside the manhole without performing the work of entering the manhole. The present invention relates to a wireless communication system that grasps and more effectively investigates the current state of manholes and internal communication facilities.

  As a wireless communication system that obtains information in a manhole in the ground, there is a long-distance wireless modem using a small area radio that remotely monitors a manhole pump (see, for example, Non-Patent Document 1). FIG. 18 is a schematic diagram showing a configuration of a wireless communication system for remotely monitoring a manhole pump according to the prior art.

  In FIG. 18, the state monitoring and management of the manhole pump installed as equipment in the manhole 500 in the suburbs are performed remotely. The manhole pump 501 in the manhole 500 is connected to the local control device 600 provided on the ground by a cable, and the manhole pump 501 is connected to the slave unit (radio unit main body) 602 housed in the waterproof protection case 601 ahead. Information is conveyed. The information of the manhole pump 501 is sent to the base unit 700 at another location in the suburbs within a distance range of about 1 km from the slave unit 602, and the status of the manhole pump 501 is monitored.

In addition, a control signal can be sent from the parent device 700 to the child device 602 in the reverse direction to control / manage the manhole pump 501. Incidentally, the base unit - For small areas radio between handset, the communication method is half-duplex communication is simplex, use frequency is used 348.56625～348.8000MHz, communication speed, 2400 bps, antenna power is 0.1 W / 1 W switching.

  A wireless relay device has been proposed as a technique for obtaining information in other manholes (see, for example, Patent Document 1). FIG. 19 is a cross-sectional view for explaining the operation of the wireless relay device according to the prior art. In FIG. 19, the radio device 5 installed in the manhole 1 transmits and receives radio waves. The radio wave transmitted from the wireless device 5 is reflected by a reflector (reflecting plate) 10 a installed directly under the lid 3 in the manhole 1. Reflected by the reflector 10a, the radiated power of the radio wave from the radio device 5 is strengthened and transmitted to the ground radio device (not shown in FIG. 19).

  As described above, the radio wave from the radio device 5 is reflected by the reflector 10a, so that the information on the manhole 1 can be obtained because the radio device on the ground can be easily received. Conversely, the radio wave from the ground radio is reflected by the same reflector 10a and reaches the radio 5, so that an instruction from outside the manhole 1, that is, from the ground can be sent into the manhole 1. .

JP 2010-50899 A

Long-distance wireless modem WM51 OMRON Small-area radio enables 1km long-distance communication, Internet <URL: http://www.fa.omron.co.jp/data_pdf/cat/wm51_sgsa-012f-1.pdf>

  In the case where information inside and outside the manhole 500 is transmitted / received by a cable (wired) as in Non-Patent Document 1 described above, a hole for passing the cable to the ceiling of the manhole 500 or to the ground is required. Such a hole has a problem in that the strength of the manhole 500 may be affected, or there may be an increase in water immersion in the manhole 500. In addition, cable laying work is necessary, and the cost of civil engineering work is enormous.

  Moreover, when installing the reflecting plate 10a under the manhole cover 3 as in Patent Document 1, when considering the position where the reflecting plate 10a is installed, the installation work and the case where an operator enters the manhole 1 Difficulty is expected. In particular, it is considered that the reflector 10a is required to have a large size in order to increase the radiation intensity of the radio wave transmitted from the wireless device 5.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a radio communication system that can easily improve the reception level of radio waves from a radio tag in a manhole in a reader on the ground. It is to provide.

  In order to solve the above-described problems, the present invention provides a wireless communication system that wirelessly transmits and receives information between a tag installed in a manhole and a reader on the ground, and is provided on the entire floor of the manhole. A radio communication system comprising an installed radio wave reflecting member.

  The present invention is characterized in that, in the above-mentioned invention, the radio wave reflecting member is further installed on one of the four side surfaces of the manhole in addition to the entire floor surface of the manhole.

  According to the present invention, in the above invention, in addition to the entire floor surface of the manhole, the radio wave reflecting member is further installed on the entire surface of two side surfaces parallel to the traveling direction of the vehicle traveling on the road. Features.

  According to the present invention, in the above invention, in addition to the entire floor surface of the manhole, the radio wave reflecting member further includes an entire surface of two side surfaces orthogonal to a traveling direction of a vehicle traveling on the road and a side surface on the roadway side. It is installed on the entire surface.

  The present invention is characterized in that, in the above invention, the radio wave reflecting member is installed on the entire surface of all side surfaces of the manhole in addition to the entire floor surface of the manhole.

  The present invention is characterized in that, in the above invention, the radio wave reflecting member is installed on the entire surface of all side surfaces and the entire surface of the manhole except for a part of the ceiling, in addition to the entire floor surface of the manhole. To do.

  The present invention is characterized in that, in the above invention, the radio wave reflecting member installed on the ceiling has a slit portion opened in a direction coinciding with a traveling direction of a vehicle traveling on the road.

  The present invention is characterized in that, in the above invention, the radio wave reflecting member installed on the ceiling has an opening opened in a part thereof.

  The present invention is characterized in that, in the above invention, the radio wave reflecting member is either a metal mesh or a reflective paint.

  In order to solve the above-described problem, the present invention is a wireless communication system that wirelessly transmits and receives information between a tag installed in a manhole and a reader on the ground, wherein the tag includes the tag A wireless communication system comprising a directional antenna having directivity corresponding to a reader's location or movement.

  According to this invention, the reception level of the radio wave from the radio tag in the manhole in the reader on the ground can be easily improved.

It is a schematic diagram which shows the structure inside the manhole using the radio | wireless communications system by 1st Embodiment of this invention. It is a conceptual diagram for demonstrating the basic principle of the electromagnetic wave condition in the conventional manhole. It is a conceptual diagram for demonstrating the basic principle of the electromagnetic wave condition in the manhole in the radio | wireless communications system by this 1st Embodiment. It is a conceptual diagram for demonstrating the manhole floor surface reflection in the radio | wireless communications system by this 1st Embodiment. It is a conceptual diagram for demonstrating the case where there is almost no manhole floor surface & side surface reflection. It is a conceptual diagram for demonstrating the manhole floor surface reflection in the radio | wireless communications system by this 1st Embodiment. It is a conceptual diagram which shows the simulation result of the reception level in the case where there is radio wave reflection on the floor in a manhole. It is a conceptual diagram for demonstrating the simulation conditions in the radio | wireless communications system by this 1st Embodiment. It is a schematic diagram which shows the structure in the manhole using the radio | wireless communications system by 2nd Embodiment of this invention. It is a schematic diagram which shows the structure of the manhole with the reflection from the manhole floor surface and three side surfaces by the 1st modification of this 2nd Embodiment. It is a schematic diagram which shows the structure of the manhole which has the reflection from the manhole floor surface and four side surfaces by the 2nd modification of this 2nd Embodiment. It is a schematic diagram which shows the structure of the manhole with reflection from the manhole floor surface, ceiling, and 4 side surfaces by the 3rd modification of this 2nd Embodiment. It is a schematic diagram which shows the structure of the manhole with reflection from the manhole floor surface, ceiling, and 4 side surfaces by the 4th modification of this 2nd Embodiment. It is a conceptual diagram which shows the structure in the manhole using the radio | wireless communications system by this 3rd Embodiment. It is a conceptual diagram which shows the structure and radiation directivity of the directional antenna 110 by this 3rd Embodiment. It is a conceptual diagram which shows an example of the reflective coating material by 4th Embodiment of this invention. It is a conceptual diagram which shows an example of the directional antenna by this 4th Embodiment. It is a schematic diagram which shows the structure of the radio | wireless communications system which monitors a manhole pump remotely by a prior art. It is sectional drawing for demonstrating operation | movement of the radio relay apparatus by a prior art.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

A. First Embodiment First, a first embodiment of the present invention will be described.
FIG. 1 is a schematic diagram showing an internal configuration of a manhole using the wireless communication system according to the first embodiment of the present invention. In FIG. 1, the radio wave from the radio tag 100 installed in the manhole 500 has a low level that can be received by the reader 200 possessed by the worker on the ground only by direct waves directed directly to the ground. May not be able to grasp the information.

  In the first embodiment, as shown in FIG. 1, in addition to the direct wave, the radio wave from the wireless tag 100 is reflected on the floor surface 510 (increase the ratio of the reflected wave on the floor surface 510) as described above. Even when the reception level of only the direct wave of the wireless tag 100 is low, the reflected waves are added together and can be received by the reader 200 on the ground (on the road).

  Therefore, in the first embodiment, the radio wave reflecting member 515 is provided on the entire surface of the floor 510 in order to reflect the radio wave on the floor surface 510 of the manhole 500. As the radio wave reflecting member 515, a metal net (mesh), a reflective paint, or the like is used. The metal net has a mesh shorter than the wavelength of the radio wave, and can be folded so as not to hinder the transportation to the inside of the manhole 500 before installation, and is installed on the floor 510 of the manhole 500. Sometimes a folded net is unfolded.

  Another example of the reflective paint is one that is applied to the inside of a plastic package of an electronic device (electromagnetic wave shield coating, conductive paint, Internet <URL: http://www.plascoat.co.jp/ shield_det.html>). This is a technique for reflecting electromagnetic waves by forming a coating film having a high conductivity on the surface of an object to be coated by applying a paint containing a metal filler by spraying.

  Here, regarding the radio wave transmitted from the wireless tag 100 installed in the manhole, the direct wave that travels straight to the ground and the reflected wave that is reflected by the floor 510 of the manhole 500 and reaches the ground, As described above, the basic principle will be described for each of the influences on the reception intensity of radio waves on the ground, and what effect the reflected waves on the side surface 520 of the manhole 500 will have when applied. .

  2A and 2B are conceptual diagrams for explaining the basic principle of a radio wave situation in a conventional manhole. FIG. 2A shows a case where there is a reflected wave only on the floor surface 510 of the normal manhole 500. FIG. 2B shows a case where a reflected wave from the side surface 520 of the normal manhole 500 is applied. In FIG. 2A, the ceiling 530 of the manhole 500 is at a depth Dm from the ground, and the floor surface 510 is at a position deeper by Hm. In the manhole 500, the wireless tag 100 is installed at a height ht from the floor 510. On the other hand, the reader 200 is at the height of the ground hr.

  In such a case, the distance from the wireless tag 100 to the reader 200 is Hm−ht + Dm + hr, and the direct wave of the radio wave transmitted from the wireless tag 100 is transmitted through this distance. On the other hand, the distance from the wireless tag 100 to the reader 200 via the floor 510 is Hm + ht + Dm + hr, and the reflected wave of the radio wave reflected on the floor travels this distance.

  For the reflected wave, if the reflectance at the floor 510 of the manhole 500 is γm (<< 1), the substantial distance until the reflected wave reaches the ground is considered to be (Hm + ht + Dm + hr) · 1 / γm. . Therefore, since the reflected wave has a very weak reception intensity when it reaches the ground compared to the direct wave, it does not differ from the reception intensity of only the direct wave on the ground. In addition, in the examination comparing the direct wave and the reflected wave shown in FIG. 2A, regarding the attenuation of each radio wave by the soil having a depth (Dm) hitting from the manhole ceiling 530 to the ground, the direct wave and the reflected wave are Both are the same and are considered offset in the comparison.

  2B, for the manhole 500, as in FIG. 2A, the manhole ceiling 530 has a depth Dm from the ground, and the Dm + Hm depth from the ground becomes the manhole floor 510, and the depth of Dm + Hm−ht. The wireless tag 100 is installed, and the reader 200 is at the ground height hr. The width of the manhole 500 is Wm. The manhole 500 is installed on the wireless tag 100 at a distance Wt from the position of one side surface 520 in the manhole 500, and the reader 200 is placed on the ground at a distance Wr from the position of the same side surface 520. There is.

In the above-described configuration, first, the direct wave A travels a linear distance from the wireless tag 100 to the reader 200, that is, √ {(Wr−Wt) ² + (hr + Dm + Hm−ht) ² }. Further, the distance from the wireless tag 100 to the reader 200 reflected by the floor surface 510 of the manhole 500 is {square root} {(Wr−Wt) ² + (hr + Dm + Hm + ht) ² }, and the reflected wave B of the floor surface 510 is this distance. Continue on.

However, since the reflectance of the radio wave on the floor 510 of the manhole 500 is as small as γm (<< 1), the substantial distance until the reflected wave B reaches the reader 200 from the wireless tag 100 is 1 / It is considered that γm · √ {(Wr−Wt) ² + (hr + Dm + Hm + ht) ² }. Furthermore, in FIG. 2B, there are two paths for the radio wave from the wireless tag 100 to be reflected by the side surface 520 of the manhole 500 and reach the reader 200, and the distance on one side is √ {(Wr + Wt) ² + (Hr + Dm + Hm−ht) ² }, and the other distance is √ {(2 Wm−Wr−Wt) ² + (hr + Dm + Hm−ht) ² }.

Since the reflected waves C and D traveling along these distances are reflected by the side surface 520 of the manhole 500, the reflectance is as small as γm (<< 1). Accordingly, the substantial distance between the reflected waves C and D described above is 1 / γm · √ {(Wr + Wt) ² + (hr + Dm + Hm−ht) ² } and 1 / γm · √ {(2Wm−Wr−Wt). ² + (hr + Dm + Hm−ht) ² }.

  The three reflected waves B, C, and D described above are extremely small when the intensity of reception by the reader 200 is compared with the direct wave A. Therefore, in the normal manhole 500, it is not expected that the reflected waves B, C, and D from the floor surface 510 and the side surface 520 are added directly to the wave A to increase the radio wave reception intensity at the ground reader 200.

  As in FIG. 2A, in the study comparing the direct wave A and the three reflected waves B, C, and D shown in FIG. 2B, the soil between the manhole ceiling 530 and the ground (Dm) Regarding the attenuation of each radio wave, the direct wave A and the three reflected waves B, C, and D are all compared under the same conditions, and the attenuation between the Dm is considered by subtracting the same amount for each radio wave comparison. Yes.

  FIGS. 3A and 3B are conceptual diagrams for explaining the basic principle of a radio wave situation in a manhole in the wireless communication system according to the first embodiment. FIG. 3A shows a manhole 500 having reflection on the floor 510. FIG. 3B shows a manhole 500 having reflection on the side surface 520 in addition to reflection on the floor surface 510.

  3A, as in FIG. 2A, there is a ceiling 530 of a manhole 500 at a depth Dm from the ground, a floor surface 510 at a depth Dm + Hm, and a manhole at a depth Dm + Hm-ht. The wireless tag 100 is installed, and the reader 200 is at a height hr on the ground. The distance from the wireless tag 100 to the reader 200 is Hm−ht + Dm + hr, the distance from which the radio tag 100 transmits a radio wave and the direct wave is transmitted to the reader 200. In addition, the distance from the wireless tag 100 via the floor 510 to the reader 200 is Hm + ht + Dm + hr, which is the distance traveled by the reflected wave of the radio wave reflected by the floor 510.

  As for the reflected wave, since the reflective paint is applied to the floor surface 510 of the manhole 500 or a metal mesh is installed, the reflectance is high (here, it is assumed that the reflectance is approximately 1). The substantial distance to reach the ground is also the same as Hm + ht + Dm + hr. Here, compared with the sum of the depth of the manhole 500, the height of the floor 510 to the ceiling 530, and the height of the reader 200 on the ground, the height from the floor 510 to the wireless tag 100 is sufficiently small (ht << Hm + Dm + hr) can also be assumed, and the distance that the reflected wave reaches the ground is almost the same as the direct wave, and the direct wave and the reflected wave are combined, and the reception intensity at the reader 200 is expected to be improved. The

3B, similarly to FIG. 2B, there is a manhole ceiling 530 at a depth Dm from the ground, a floor surface 510 at a depth Dm + Hm, and the wireless tag 100 at a height ht from the floor. There is a reader at the height hr. In addition, the width of the manhole 500 is Wm, the wireless tag 100 is located at a position Wt from one side 520, and the ground reader 200 is located at a distance Wr from the same side 520. Under this condition, the distance wirelessly from the tag 100 to the reader 200 direct wave a is ^{√ {(Wr-Wt) 2} + (hr + Dm + Hm-ht) 2}, the reflected wave b on the floor 510, √ { The distance of (Wr−Wt) ² + (hr + Dm + Hm + ht) ² } is advanced.

Here, the floor 510 of the manhole 500 in FIG. 3B is coated with a reflective paint or is provided with a metal mesh, and almost reflects radio waves (reflectance ≈ 1). The reflected wave b becomes a substantial distance from √ {(Wr−Wt) ² + (hr + Dm + Hm + ht) ² } to reach the reader 200 from the wireless tag 100 (this point is shown in FIG. 2B). Different from the reflected wave B). Further, in FIG. 3B, the radio wave transmitted from the wireless tag 100 and reflected by the side surface 520 of the manhole 500 reaches the reader 200 through two paths. One distance is √ {(Wr + Wt) ² + (hr + Dm + Hm−ht) ² }, and the other is √ {(2 Wm−Wr−Wt) ² + (hr + Dm + Hm−ht) ² }.

The reflected waves c and d traveling along these distances are reflected by the side surface 520 of the manhole 500, but the side surface 520 is coated with a reflective paint or a metal mesh is installed to reflect most radio waves. Therefore, for the reflected waves c and d, √ {(Wr + Wt) ² + (hr + Dm + Hm−ht) ² } and √ {(2 Wm−Wr−Wt) ² + (hr + Dm + Hm−ht) ² } is a substantial distance. From the description so far, the distance from the wireless tag 100 to which the direct wave a travels to the reader 200 and the substantial distance traveled by the three reflected waves b, c, and d are almost the same.

  Assuming here, the height of the wireless tag 100 from the floor 510 is sufficiently smaller than the total depth of the manhole 500, the height of the floor 510 to the ceiling 530, and the height of the reader 200 above ground (ht << Hm + Dm + hr). ). As another assumption, the position where the wireless tag 100 and the reader 200 are installed is about half the width of the manhole 500 from one side of the manhole 500 (Wr≈Wt≈Wm / 2).

  That is, it is assumed that it is in the center of the manhole 500. Therefore, the intensity of reception by the reader 200 with these four radio waves, that is, the direct wave a and the reflected waves b, c, and d, is approximately the same. Therefore, in the normal manhole 500, it is expected that the reflected waves b, c, and d from the floor surface 510 and the side surface 520 are added to the direct wave a to increase the radio wave reception intensity at the ground reader 200.

  FIG. 4 is a conceptual diagram for explaining manhole floor surface reflection in the wireless communication system according to the first embodiment. Also in FIG. 4, similarly to FIG. 1, the radio wave of the wireless tag 100 installed in the manhole 500 is reflected by the floor surface 510 provided with the radio wave reflection member 515 (the intensity of the reflected wave is increased). By reflecting the radio wave from the wireless tag 100 on the floor surface 510, the reception range of the reader 200 can be expanded on the ground (on the road).

  As a result, considering that the reader 200 mounted on the traveling vehicle (automobile) 300 receives radio waves from the wireless tag 100, information from the wireless tag 100 can be transmitted to the vehicle 300 even when the traveling speed of the vehicle 300 is high. It can be acquired by the installed reader 200.

  In order to reflect radio waves on the floor surface 510 of the manhole 500, as described above, the radio wave reflecting member (reflective paint, metal mesh having a mesh shorter than the wavelength of the radio wave) is provided on the floor surface 510. . As the reflective paint, the electromagnetic wave shielding coating and conductive paint described in FIG. 1 are preferable, and the metal mesh is preferably one that can be folded during transportation before installation and can be unfolded during use. .

  Here, FIG. 5 is a conceptual diagram for explaining a case where there is almost no manhole floor and side reflection. In FIG. 5, as shown in FIG. 4, the radio wave of the wireless tag 100 is reflected by the floor surface 510 of the manhole 500. This shows a case where there is no reflection of radio waves from the tag 100, or a case where there is little reflection of radio waves even if there is a reflection on the floor surface 510.

  In such a case, the radio wave from the wireless tag 100 by the reader 200 on the ground is almost only a straight wave, or most of the radio wave reflected by the floor 510 is a straight wave. The reception level of radio waves from the wireless tag 100 on the ground is weakened. For this reason, the range in which the reader 200 can receive radio waves from the wireless tag 100 on the ground is limited to a narrow range (solid circle). That is, the reader 200A located sufficiently close to the manhole 500 can receive radio waves from the wireless tag 100, but the reader 200B far from the manhole 500 cannot receive radio waves from the wireless tag 100. .

  FIG. 6 is a conceptual diagram for explaining manhole floor surface reflection in the wireless communication system according to the first embodiment. 6 shows the manhole 500 on the road in the same place as FIG. 5, but the point where the radio wave from the wireless tag 100 is reflected on the floor surface 510 of the manhole 500, or the radio wave reflected on the floor surface 510. Are different in that they have the same strength as radio waves traveling straight from the wireless tag 100 to the ground.

  Radio waves transmitted by the wireless tag 100 include radio waves that are reflected on the floor 510 of the manhole 500 and transmitted to the ground in addition to radio waves that travel straight to the ground. As a result, the reception range of the reader 200 on the ground, that is, on the road, can be expanded by the amount of radio waves reflected by the floor 510 of the manhole 500. That is, the radio wave from the wireless tag 100 can be received by either the reader 200 </ b> A located sufficiently close to the manhole 500 or the reader 200 </ b> B far from the manhole 500.

  FIG. 7 is a conceptual diagram showing a simulation result of the reception level when there is / without radio wave reflection on the floor in a manhole. That is, FIG. 7 shows the difference in the reception level obtained by simulation when there is / without reflection on the floor 510 of the manhole 500. The horizontal axis of the graph shown in FIG. 7 is the reception level of the radio wave transmitted from the wireless tag 100, and the vertical axis is the height from the floor 510 of the manhole 500 and indicates the position of the receiving antenna.

  The dashed line in the graph shown in FIG. 7 indicates that the floor 510 of the manhole 500 is concrete, that is, the radio wave 100 is slightly reflected on the floor 510 and the position of the wireless tag 100 transmitting the radio wave is the floor of the manhole 500. The case of 510 to 2.06 m is shown. The solid line indicates a case where the floor surface 510 of the manhole 500 is copper and the position of the wireless tag 100 that transmits radio waves is 2.06 m from the floor surface 510 of the manhole 500.

  The dotted line indicates that the floor surface 510 of the manhole 500 is copper, and the position of the wireless tag 100 that transmits radio waves is ¼ of the wavelength from the floor surface 510 of the manhole 500, that is, a height of 3.4 cm. Is shown. Further, the broken line indicates a case where the free space, that is, no radio wave is reflected on the floor 510 of the manhole 500 and the position of the wireless tag 100 transmitting the radio wave is 2.06 m from the floor 510 of the manhole 500.

  When a copper plate is arranged on the dotted manhole floor 510 with respect to the free space indicated by the broken line and the transmitting antenna is installed at a height of ¼ wavelength, it is 4 m or more from the floor 510 of the manhole 500, that is, 1 m above the ground. When there is a receiving antenna at the above height, the reception level of radio waves exceeds all, and the difference in the reception level increases as the position of the receiving antenna increases.

  When the copper plate is placed on the solid manhole floor 510 and the transmitting antenna is installed at a height of 2.06 m as compared with the one-dot chain line concrete, the receiving antenna slightly differs from the floor 510 of the manhole 500 by 3 m. In other words, at the point exceeding 4 to 6 m, in other words, the reception level is high in the range of a slight height above the ground and from 1 to 3 m above the ground.

  In addition, a transmission antenna is installed at a height of 2.06 m even on the same copper floor surface indicated by a solid line as opposed to a transmission antenna placed at a quarter wavelength height on the copper floor surface indicated by a dotted line. In this case, the reception level is high at a height of 3 m from the floor 510 of the manhole 500 and around 4-5 m, in other words, in a range close to the ground and 1-2 m above the ground.

  From these simulation results, by placing a material that reflects radio waves such as copper on the floor 510 of the manhole 500, the reception level on the ground can be improved, or by devising the height at which the transmission antenna is installed, It can be seen that there is a difference in the reception level.

  FIG. 8 is a conceptual diagram for explaining simulation conditions in the wireless communication system according to the first embodiment. FIG. 8 shows a situation such as a manhole size parameter used in the simulation shown in FIG. First, as shown in FIG. 8, the manhole 500 has a lid, a doorway, a ceiling, a side surface, and a floor surface 510. However, in order to obtain the strongest reflection effect by a simple simulation, there is only the floor surface 510. Is assumed. The floor 510 is made of concrete, which is a material of a general manhole 500, a reflective paint as the radio wave reflecting member 515, copper as a metal mesh, or a free space (floor surface as a situation where no radio wave is reflected). Is a simulation condition example.

  The floor position of a typical manhole 500 may be considered to be 3 m from the ground. The position where the wireless tag 100 is installed with respect to such a manhole 500 determines the height from the floor 510, and the position of the wireless tag 100 is the height of the transmitting antenna. Moreover, since the height of the reader 200 is the reception Rx antenna height, and this height is also used as a reference for the floor surface of the manhole 500, it is only necessary to confirm a height of 3 m or more above the ground.

  The height of the reception Rx antenna is changed, and the reception level of the radio wave (a combination of the direct wave and the reflected wave) from the transmission antenna described above is obtained at the height of the reception Rx antenna. Thus, under the simulation conditions shown in FIG. 8, in the simulation results shown in FIG. 7, four examples, that is, the floor surface 510 is concrete (transmitting antenna height = 2.06 m), and the floor surface is copper (transmission). Antenna height = 2.06 m) as a solid line, copper (transmitting antenna height = 3.4 cm (1/4 wavelength)) as a dotted line, and free space (transmitting antenna height = 2.06 m) as a broken line Is shown.

  According to the first embodiment described above, the radio wave reflecting member (reflective paint or metal mesh) 515 that reflects the radio waves of the wireless tag 100 installed in the manhole 500 is installed on the floor 510 of the manhole 500. As described above, it is possible to easily collect information in the manhole and give instructions from the ground without a cable from the inside of the manhole 500 to the ground.

B. Second Embodiment Next, a second embodiment of the present invention will be described.
FIG. 9 is a schematic diagram showing a configuration in a manhole using the wireless communication system according to the second embodiment. In the second embodiment, radio waves from the wireless tag 100 are reflected on the manhole floor and side surfaces. In FIG. 9, in a manhole 500, a radio wave reflecting member (paint or mesh) 515 that reflects radio waves is installed on the floor 510 and two side surfaces 520A and 520C that are parallel to the direction in which the vehicle 300 travels on the road.

  On the left side of FIG. 9, a development view of the inner surface of the manhole 500 is shown. In the developed view, there is an entrance / exit in the center of the ceiling 530, and side surfaces 520A, 520B, 520C, and 520D are shown clockwise with respect to the floor surface 510. The radio wave reflecting member (paint or mesh) 515 is installed on the floor surface 510 and side surfaces 520A and 520C parallel to the direction in which the vehicle 300 travels on the road.

  As described above, since the radio wave reflecting member (paint or mesh) 515 is installed, the radio wave transmitted from the wireless tag 100 installed in the manhole 500 includes a direct wave to the ground, The floor surface 510 and the reflected waves from the two side surfaces 520A and 520C are added. By adding the direct wave to the floor surface 510 and the reflected waves from the two side surfaces 520A and 520C, the reception range where the radio wave of the wireless tag 100 reaches in the traveling direction of the vehicle 300 is expanded.

B-1. First Modification FIG. 10 is a schematic diagram showing a configuration of a manhole with reflection from the manhole floor and three side surfaces according to a first modification of the second embodiment. As shown in FIG. 9 described above, the radio wave reflecting member (paint or mesh) 515 is installed on the floor 510 in the manhole 500 and the two side surfaces 520A and 520C parallel to the traveling direction of the vehicle 300. In the first modification, as shown in FIG. 10, a radio wave reflecting member (paint or mesh) 515 is installed on the floor 510 in the manhole 500 and the three side surfaces 520A, 520B, and 520D excluding the sidewalk. Has been. In other words, the radio wave reflecting member (paint or mesh) 515 is provided with the radio wave reflecting member (paint or mesh) 515 on the two side surfaces 520B and 520D orthogonal to the traveling direction of the vehicle 300 and the side surface 520A on the roadway side. Yes.

  As in FIG. 9, a development view is shown on the left side of FIG. 10, the ceiling 530, the floor surface 510, and the side surfaces 520A, 520B, 520C, and 520D are at the same positions as in FIG. In FIG. 10, radio wave reflecting members (paint or mesh) 515 are installed on the floor surface 510 and the side surfaces 520A, 520B, and 520D in the developed view. Thereby, the radio wave from the wireless tag 100 installed in the manhole 500 is reflected on the floor 510 of the manhole 500 and the radio wave reflecting member (paint or mesh) 515 on the three side surfaces 520A, 520B, and 520D. Reach a wide area in the direction of the sidewalk. As a result, the radio wave from the wireless tag 100 inside the manhole 500 can easily reach the telephone BOX 400 on the sidewalk.

B-2. Second Modification Example FIG. 11 is a schematic diagram showing a configuration of a manhole with reflection from the manhole floor surface and four side surfaces according to a second modification example of the second embodiment. In FIG. 11, a manhole 500 is provided with a radio wave reflecting member (paint or mesh) 515 on a floor surface 510 other than the ceiling 530 and all side surfaces 520A, 520B, 520C, and 520D.

  Similarly to FIG. 9 and FIG. 10, a development view is shown on the left side of FIG. 11. A radio wave reflecting member (paint or mesh) 515 is installed on the floor 510 of the manhole 500 and all of the side surfaces 520A, 520B, 520C, and 520D. Thereby, the radio wave from the wireless tag 100 installed in the manhole 500 is reflected on the floor 510 of the manhole 500 and the radio wave reflecting members (paint or mesh) 515 of all the side surfaces 520A, 520B, 520C, and 520D. As a result, the intensity of radio waves increases to the ground above the manhole 500. As a result, radio waves from the wireless tag 100 inside the manhole 500 are easily received on the ground in the range above the manhole 500.

  Accordingly, when the inspection worker holds the reader 200 on the ground above the manhole 500 and receives the radio wave from the radio tag 100 installed in the manhole 500, the inspection worker transmits the radio wave transmitted from the radio tag 100. In addition to the direct wave, the reflected wave of the radio wave by the floor surface 510 of the manhole 500 and the reflected waves by all the side surfaces 520A, 520B, 520C, and 520D are also received. For this reason, compared to a level where only the direct wave of the radio wave from the wireless tag 100 is received, the reception level of the reflected waves from all the side surfaces 520A, 520B, 520C, and 520D of the floor surface 510 is improved, so that it is more accurate. Then, the signal from the wireless tag 100 can be received.

B-3. Third Modification FIG. 12 is a schematic diagram showing the configuration of a manhole having reflections from the manhole floor, ceiling, and four side surfaces according to a third modification of the second embodiment. In FIG. 12, in a manhole 500, a radio wave reflecting member (paint or mesh) 515 is installed on a floor surface 510 and all side surfaces 520A, 520B, 520C, and 520D including a ceiling 530. In the perspective view of FIG. 12, the side surfaces 520B and 520D and the radio wave reflecting member (paint or mesh) 515 installed on the ceiling 530 are omitted.

  The manhole 500 shown in FIG. 11 has a radio wave reflecting member (paint or mesh) 515 installed on the floor surface 510 below the ceiling 530 and all the side surfaces 520A, 520B, 520C, and 520D. The manhole 500 shown in FIG. Further, a radio wave reflecting member (paint or mesh) 515 is also installed on the ceiling 530 except for the line-shaped slit portion 516. When viewed from the entire interior of the manhole 500, it appears that the line-shaped slit portion 516 of the ceiling 530 is open. The direction of the slit portion 516 coincides with the traveling direction of the vehicle 300 on the road.

  As in FIGS. 9 to 11, a development view is shown on the left side of FIG. As is clear from the developed view shown on the left side of FIG. 12, the radio wave reflecting member (paint or mesh) 515 is formed on all surfaces of the manhole 500, that is, the floor surface 510, the four side surfaces 520A, 520B, 520C, 520D and the ceiling 530. Is installed. However, only the slit portion 516 is cut in the longitudinal direction of the ceiling 530, and the side surfaces 520B and 520D corresponding to the extending direction of the slit portion 516 also have slit ends. The ceiling 530 and the slit portions (end portions) 516 of the side surfaces 520B and 520D are in a range where there is no radio wave reflecting member (paint or mesh) 515.

  Therefore, the radio wave is reflected by the radio wave reflecting member (paint or mesh) 515 installed on the floor 510, the side surfaces 520A, 520B, 520C, and 520D, which is the most part of the manhole 500, and the inside of the manhole 500. Returned. Then, only through the slit portion 516, the radio wave transmitted from the wireless tag 100 goes out of the manhole 500. Further, since radio waves reflected at various locations inside the manhole 500 are also added, the transmission level of the radio waves coming out of the manhole 500 from the slit portion 516 becomes strong.

  In other words, the radio wave of the wireless tag 100 installed inside the manhole 500 is confined inside the manhole 500 to the most extent, but is only transmitted from the slit portion 516 to the outside of the manhole 500. Is in a state. Therefore, the range in which radio waves from the wireless tag 100 can be received on the ground above the manhole 500 is expanded in a direction that coincides with the slit portion 516, and is received by the reader 200 mounted on the vehicle 300 traveling on the road. In addition, even the vehicle 300 moving at a faster speed can receive the signal of the wireless tag 100.

B-4. Fourth Modified Example FIG. 13 is a schematic diagram showing a configuration of a manhole having reflections from the manhole floor, ceiling, and four side surfaces according to a fourth modified example of the second embodiment. Also in FIG. 13, as shown in FIG. 12, a radio wave reflecting member (paint or mesh) 515 is installed on the floor 510 of the manhole 500, all the side surfaces 520A, 520B, 520C, 520D, and the ceiling 530 except for a part thereof. In the perspective view of FIG. 12, the side surfaces 520B and 520D and the radio wave reflecting member (paint or mesh) 515 installed on the ceiling 530 are omitted.

  The fourth modification is different from the configuration shown in FIG. 10 in that an opening 517 in which a radio wave reflecting member (paint or mesh) 515 is not installed is provided in a part of the ceiling 530 as shown in FIG. There is in doing. In FIG. 12, the slit portion 516 has a shape that matches the traveling direction of the road. However, in the fourth modification, as shown in FIG. 13, the radio wave reflecting member is provided at one corner of the ceiling 530. (Paint or mesh) 515 is not installed.

  As in FIGS. 9 to 12, a development view is shown on the left side of FIG. As shown on the left side of FIG. 13, a radio wave reflecting member (paint or mesh) 515 is installed on almost the entire inner surface of the manhole 500, that is, the floor 510, the four side surfaces 520A, 520B, 520C, and 520D, and most of the ceiling 530. Has been. However, in the manhole 500, a part of the ceiling 530 is provided with an opening 517 that does not have a radio wave reflecting member (paint or mesh) 515 and is permeable to radio waves.

  Most of the radio waves from the wireless tag 100 installed in the manhole 500 are reflected by the radio wave reflecting member (paint or mesh) 515 installed inside the manhole 500, and all from the opening 517 that is transparent to the radio waves. It will be discharged out of the manhole 500. Accordingly, the intensity of the radio wave from the wireless tag 100 that is transmitted from the opening 517 that is formed in a part of the ceiling 530 and does not have the radio wave reflecting member (paint or mesh) 515 is increased. The radio wave of the wireless tag 100 can be received by the reader 200 at a position on the ground that hits the opening 517 where the radio wave reflecting member (paint or mesh) 515 of the ceiling 530 is not installed.

  According to the above-described second embodiment, in addition to the floor 510 of the manhole 500, the radio wave reflecting member (paint or mesh) 515 is also installed on the side surfaces 520A and 520C parallel to the direction in which the vehicle 300 travels on the ground road. Or by installing a radio wave reflecting member (paint or mesh) 515 on the floor 510 of the manhole 500 or any of the side surfaces 520A, 520B, 520C, and 520D, from the wireless tag 100 only in a specific direction. The manhole 500 is also used when the radio wave (direct wave, reflected wave) is transmitted and the vehicle 300 traveling at a high speed on the road, the reader 200 installed on the telephone BOX 400 on the road, or receiving directly above the ground. It is possible to easily and reliably receive radio waves from the wireless tag 100.

  Further, a radio wave reflecting member (paint or mesh) 515 is disposed in a range excluding the floor 510 inside the manhole 500, all of the side surfaces 520A to 520D, and a part of the ceiling 530, and a part of the manhole ceiling 530 is By forming slits 516 or openings 517 that coincide with the traveling direction of the vehicle 300 on the ground road, workers on the leader 200 mounted on the vehicle 300 traveling at a higher speed or on the ground on the manhole Can easily and reliably receive radio waves from the wireless tag 100 of the manhole 500.

C. Third Embodiment Next, a third embodiment of the present invention will be described.
FIG. 14 is a conceptual diagram showing a configuration in a manhole using the wireless communication system according to the third embodiment. In the third embodiment, the wireless tag 100 includes an antenna 110 having directivity. The directivity of the antenna 110 is wide in the direction in which the vehicle 300 on the road travels and narrow in the vertical direction. As described with reference to FIG. 9 and FIG. 12, the radio wave reflecting member (paint or mesh) 515 is disposed on the floor surface 510, the side surfaces 520 </ b> A to 520 </ b> D of the manhole 500, and the ceiling 530. This has the same effect as the embodiment.

  That is, by connecting a directional antenna 110 as shown in FIG. 14 to the wireless tag 100, when the wireless tag 100 having the same output and transmission power is used, the vehicle 300 traveling at a higher speed on the road. It becomes easy to receive the radio wave of the wireless tag 100 by the reader 200 mounted on the. As an example of the antenna 110 having this directivity, there is a bi-directional patch / slot combined antenna (BNPSA). This BNPSA has a configuration in which a bidirectional slot antenna (BSA) and a bidirectional narrow patch antenna (BNPA) are combined.

  FIGS. 15A and 15B are conceptual diagrams showing the structure and radiation directivity of the directional antenna 110 according to the third embodiment. Fig. 15 (a) shows the structure of BNPSA, and Fig. 15 (b) shows the radiation directivity of the BNPSA (Reference 1: Chokeizo Naga, Toshikazu Hori, Hajime Serizawa "Polarized service with bi-directionality". Base station antenna ", Internet <URL: http://ci.nii.ac.jp/naid/110003339814>). As shown in FIG. 15B, the radiation directivity of the antenna is wide in a certain linear direction (left-right direction in FIG. 15B) and narrow in the vertical direction (up-down direction in FIG. 15B). Have

  According to the above-described third embodiment, the wireless tag 100 installed in the manhole 500 has a directivity adapted to the location of the reader 200 that receives the antenna and the movement. The radio signal transmitted by the wireless tag 100 can be easily received by the reader 200 on the ground.

D. Fourth Embodiment Next, a fourth embodiment of the present invention will be described.
In the first and second embodiments described above, the reflective paint has been described as one of the radio wave reflecting members 515. In the third embodiment described above, the example in which the antenna 110 having directivity is connected to the wireless tag 100 has been described. The fourth embodiment shows a specific example of the reflective paint and another example of a directional antenna.

  FIG. 16 is a conceptual diagram showing an example of a reflective paint according to the fourth embodiment. FIG. 16 shows the inside of a package 800 of an electronic device to which the reflective paint 515a is applied. As shown in FIG. 16, the electronic noise generated from the electronic device is prevented from leaking outside by applying a reflective paint 515a inside the package 800. By applying the same reflective paint 515 a to the floor 510, the side surfaces 520 </ b> A to 520 </ b> D, or the ceiling 530 of the manhole 500, the radio wave transmitted from the wireless tag 100 installed inside the manhole 500 can be reflected. The advantage of the reflective paint 515a is that it can be applied uniformly without being affected by the object to be applied, in this case, the wall shape of the manhole 500.

  FIG. 17 is a conceptual diagram showing an example of a directional antenna according to the fourth embodiment. As the directional antenna, in addition to the patch / slot composite antenna (BNPSA) 110 shown in FIG. 15, as shown in FIG. 17, an active array using a collinear antenna 110a (reference 2: from antenna basics to applications, Internet <URL: http://www.interq.or.jp/blue/rhf333/ANT-K.htm>, Reference 3: Traveling Wave Antenna Low Wave Antenna Frequency Band Characteristics Termination Resistance Resonance State Ronbivic Antenna-1 AM Radio Engineering in the year of August 2016, the Internet <URL: http://www.gxk.jp/elec/musen/1ama/H16/html/H1608A19_.html>).

  According to the above-described fourth embodiment, the antennas 110 and 110a having various directivities shown in FIG. 15 and FIG. 17 are connected to the wireless tag 100 installed in the manhole 500 as shown in FIG. By applying the reflective paint 515a to the floor 510 in the manhole 500, the side surfaces 520A to 520D, and the ceiling 530, the radio wave transmitted by the wireless tag 100 can be easily received by the reader 200 on the ground.

  According to the present invention, information in a manhole can be easily collected on the ground, and maintenance and inspection of various devices related to social infrastructure such as electricity, gas, water, and communication used by manhole facilities can be facilitated. . This also makes it possible to detect in advance a sign of an abnormal manhole condition.

100 wireless tag 110 antenna 110a collinear antenna 200, 200A, 200B reader 300 vehicle 400 telephone BOX
500 Manhole 510 Floor 515 Radio wave reflecting member 515a Reflective paint 520 Side 520A Side A
520B Side B
520C Side C
520D Side D
530 Ceiling

Claims (9)

A wireless communication system that wirelessly transmits and receives information between a tag installed in a manhole and a reader on the ground,
A radio communication system comprising a radio wave reflecting member installed on the entire floor of the manhole. The radio wave reflecting member is:
The wireless communication system according to claim 1, wherein the wireless communication system is installed on one of four side surfaces of the manhole in addition to the entire floor of the manhole. The radio wave reflecting member is:
3. The wireless communication system according to claim 2, wherein the wireless communication system is installed on the entire surface of two side surfaces parallel to the traveling direction of the vehicle traveling on the road in addition to the entire floor surface of the manhole. The radio wave reflecting member is:
In addition to the entire floor of the manhole, it is further installed on the entire surface of the two side surfaces orthogonal to the traveling direction of the vehicle traveling on the road and the entire surface of the side surface on the roadway side. The wireless communication system described. The radio wave reflecting member is:
The wireless communication system according to claim 2, wherein the wireless communication system is installed on the entire surface of all side surfaces of the manhole in addition to the entire floor surface of the manhole. The radio wave reflecting member is:
Further, the wireless communication system according to claim 3 in any one of 5, characterized in that installed on the entire surface except a part of the ceiling of the manhole. The radio wave reflecting member installed on the ceiling is
The wireless communication system according to claim 6 , further comprising a slit portion that opens in a direction that coincides with a traveling direction of the vehicle traveling on the road. The radio wave reflecting member installed on the ceiling is
The wireless communication system according to claim 6, further comprising an opening that is opened at a part thereof. The radio wave reflecting member is:
9. The wireless communication system according to claim 1, wherein the wireless communication system is one of a metal mesh and a reflective paint.