JP6184066B2 - Anti-air sign - Google Patents

Description

  The present invention relates to an anti-air sign detected by a synthetic aperture radar (SAR).

  In natural disasters such as earthquakes, tsunamis, and landslides caused by heavy rains, roads and communication infrastructure may become unusable, leading to isolated settlements, which may make it difficult to grasp the damage situation. In addition, when the disaster area covers a wide area, it is difficult to quickly grasp the entire picture. In such a case, it is effective to grasp the situation from above using an aircraft such as a helicopter.

  An earth observation satellite can also be used as a grasping means from above. In this regard, multiple space agencies around the world, including the Japan Aerospace Exploration Agency (JAXA), participated in the event of a large-scale disaster and contributed to mitigation of the crisis caused by the disaster by utilizing the resources of other organizations' earth observation satellites. There is a framework for international cooperation called “International Disaster Charter”.

  Earth observation satellites include optical satellites that perform imaging with visible light, and SAR satellites that include SAR that transmits radio waves toward the ground and analyzes the reflected waves.

  In past disasters, for example, in the schoolyard of the evacuation area, a letter of “SOS” requesting relief and a “H” mark for requesting landing of a helicopter are drawn to a relief sign for observation from the sky. In some cases, aircraft and optical satellites detected this, leading to early relief measures.

  In addition, as part of disaster prevention efforts, there are also training such as the formation of large relief characters by elementary school children.

  In this way, in order to convey the presence of victims and requests for relief to observations from above the disaster-stricken area, the ground surface (the surface of the feature, such as the rooftop, where there is a feature such as the ground or a building) It is effective to provide a sign.

  On the other hand, observation from above with an aircraft becomes difficult in bad weather or at night. Even in fine weather, there is a limit when the disaster area covers a wide area. In this regard, the Earth observation satellite can observe a wide area, but the optical satellite cannot capture the surface condition like an aircraft if the sky is covered with clouds or at night. In this respect, microwaves have a longer wavelength than visible light, and therefore pass through clouds. Therefore, the SAR satellite in the microwave band is not affected by the weather and can be observed even at night.

JP-A-8-166241

  There is a corner cube reflector as a device for reflecting the radio wave irradiated from the SAR to the ground surface to the SAR. The SAR satellite can detect the corner cube reflector based on the strong reflection. However, in order to return strong reflection, it is necessary to install the corner cube reflector with the opening surface facing the direction of arrival of radio waves. Therefore, when a corner cube reflector is to be used as an anti-air sign in a disaster-stricken area, the victims are generally installed without knowing the orbit of the SAR satellite. It will not be detected until a specific SAR satellite emits radio waves. In the worst case, even if there is no satellite that emits radio waves from the direction in which the aperture faces, it cannot be detected. Therefore, there is a problem that there is a possibility that the rescue cannot be performed quickly.

  The present invention has been made to solve the above problems, and an object thereof is to provide an anti-air sign that is easy to install and can be detected early after installation by a plurality of SAR satellites.

  (1) The anti-air sign according to the present invention is an anti-air sign that can be detected by a synthetic aperture radar, and a pillar portion standing on the ground surface, and a flat surface portion laid on the ground surface around the pillar portion, The column part and the flat part are made of a material that reflects electromagnetic waves transmitted by the synthetic aperture radar.

  (2) In the anti-air marker according to the above (1), the column part may be a cylinder or a shape in which a plurality of cylinders are bundled.

  (3) In the anti-air sign according to the above (1) or (2), the upper surface of the flat part has a color having a higher reflectance than the surrounding features, and can be detected by photographing visible light from the sky. can do.

  (4) In the antiaircraft sign according to the above (1) or (2), the planar portion is separable from the pillar portion, and it is possible to select which surface is laid as an upper surface, and one surface of the planar portion Is a color that can be detected by photographing with visible light from above, and the other surface has a reflectance different from that of the one surface and can be distinguished from the one surface by photographing with visible light. it can.

  (5) In the antiaircraft sign according to the above (1) to (4), the pillar part and the planar part can be separated, and the planar part is made of a flexible material and can be folded. Can have a cavity capable of accommodating the folded flat portion.

  (6) In the antiaircraft mark according to the above (1) to (5), the planar portion has a sheet-like main portion and a frame portion provided at an edge of the main portion and surrounding the main portion, The frame part may be inflated by injecting a fluid to make the edge of the flat part higher than the inside.

  (7) The anti-air marker according to the present invention includes the anti-air marker of the above (4) arranged on the ground surface, and the identification contents can be identified by a combination pattern of the plane directions of the plane portions. To do.

  Since the anti-air sign according to the present invention has a wide range of arrival directions of radio waves that can suitably return reflected waves, it is almost omnidirectional without considering the orbit of the SAR satellite (since the earth observation satellite SAR does not emit radio waves in the vertical direction, It can be installed against the arrival of radio waves from (except the above). This facilitates the installation of the anti-air sign and shortens the time until the anti-air sign is detected because the SAR satellite easily passes the position where the anti-air sign can be detected.

It is a schematic perspective view of the anti-air sign which is embodiment of this invention. It is a schematic plan view of the anti-air sign which is embodiment of this invention. It is a schematic diagram which shows the anti-air mark installed in the earth surface, and the SAR satellite and optical satellite which pass the sky. It is a schematic diagram which shows a mode that an anti-air sign reflects the irradiation wave from a SAR satellite. It is a general | schematic vertical sectional view at the time of use of the anti-air marker which can decompose | disassemble a pillar part. It is a general | schematic vertical sectional view at the time of non-use of the anti-air marker which can decompose | disassemble a pillar part. It is a schematic diagram explaining the plane part from which a color differs on both surfaces. It is a typical top view of the anti-air marker which combined four anti-air markers which consist of a pillar part and a plane part. It is a schematic perspective view of the anti-air sign which shows the other example of a pillar part.

  Hereinafter, an anti-air mark which is an embodiment of the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  FIG. 1 is a schematic perspective view of an anti-air sign 2 according to an embodiment. FIG. 2 is a schematic plan view of the anti-air sign 2. The anti-air sign 2 includes a column part 4 and a plane part 6. The column part 4 is a column shape that is erected basically perpendicular to the ground surface, and the planar shape (cross-sectional shape perpendicular to the axis of the column) is a circle or a rotationally symmetric shape having isotropic properties relatively close to a circle. And In the anti-air sign 2 shown in FIGS. 1 and 2, the pillar portion 4 is a cylinder. The flat portion 6 is laid on the ground surface around the pillar portion 4 and forms a basically flat upper surface. For example, the planar shape of the planar portion 6 can be a square or a circle. In this embodiment, the column part 4 and the plane part 6 are separable, and after the plane part 6 is laid on the ground surface, the anti-air sign 2 is constructed by installing the column part 4 near the center thereof.

  The part which becomes the surface of the pillar part 4 and the flat upper surface of the flat part 6 is made of a material that reflects electromagnetic waves transmitted by the SAR. The column part 4 can be made of a metal cylinder, for example. The flat portion 6 can be made of, for example, a vinyl sheet.

  Further, at least one surface of the flat portion 6 is white or yellow, and by laying this surface as an upper surface, the anti-air marker 2 can be detected by photographing visible light from above.

  Although the flat surface portion 6 may be only the flat sheet-like main portion 8, in the present embodiment, the flat portion 6 includes a frame portion 10 that is provided at an edge of the main portion 8 and surrounds the main portion 8. The frame 10 can be inflated by injecting a fluid such as water or air. A tab 12 is attached to the frame portion 10, and a peg can be driven into the tab 12 to fix the flat portion 6 to the ground surface.

  FIG. 3 is a schematic diagram showing the anti-air sign 2 installed on the ground surface 20 and the SAR satellites 22 (22a, 22b) and the optical satellite 24 passing through the sky. The two SAR satellites 22a and 22b are positioned in different azimuths as viewed from the anti-air marking 2, and irradiate microwave irradiation waves 26 (26a and 26b) at different incident angles. Since the SAR satellite orbits the earth in ascending and descending orbits and radiates radio waves toward the lower right or the lower left in the direction perpendicular to the traveling direction of the satellite, it has an incident angle of about 20 to 40 °. To shoot. The optical satellite 24 images the ground surface 20 with an optical sensor.

  FIG. 4 is a schematic diagram showing how the anti-air sign 2 reflects the irradiation waves 26a and 26b from the SAR satellites 22a and 22b. In the anti-air marking 2, the side surface of the column part 4 and the upper surface of the main part 8 of the plane part 6 are perpendicular to any direction. For example, when the irradiation wave 26 a transmitted from the SAR satellite 22 a in the direction toward the axis of the column part 4 is incident on the upper surface of the main part 8, the irradiation wave 26 a is reflected on the upper surface of the main part 8, and the reflected wave 28 a is reflected on the column part 4. Incident on the side of Then, the reflected wave 28a that has entered the region of the side surface of the column 4 that is substantially orthogonal to the direction in which the irradiation wave 26a has arrived is reflected in the direction in which the irradiation wave 26a has arrived to generate a reflected wave 30a. That is, the reflected wave 30a is on the same vertical plane as the irradiation wave 26a. Furthermore, since the upper surface of the main part 8 that generates the reflected wave 28a and the side surface of the column 4 that generates the reflected wave 30a are orthogonal to each other as described above, the reflected wave 30a is parallel to the irradiation wave 26a on the vertical plane and reverse. Proceed in the direction. Therefore, the reflected wave 30a reaches the SAR satellite 22a, and the anti-air marker 2 is detected based on the received signal.

  Although the reflection of the irradiation wave 26a has been described above, the same applies to the irradiation wave 26b having a different azimuth and incident angle. The reflected wave 30b of the anti-air sign 2 with respect to the irradiation wave 26b reaches the SAR satellite 22b, and the anti-air mark 2 Detected. Further, when the irradiation waves 26a and 26b are incident on the side surfaces of the column part 4, the microwaves reversely follow the above-described path and return to the SAR satellites 22a and 22b. In this case, the anti-air sign 2 is detected.

  Thus, since the anti-air marking 2 has a wide range of arrival directions of radio waves that can suitably return reflected waves to the SAR satellite 22, the orbit of the SAR satellite 22 is taken into consideration in the installation, or is matched to the orbit of the SAR satellite 22. There is no need to adjust the installation state, installation and handling are easy, and it is easy to use during a disaster. In addition, since the time until the SAR satellite reaches the position where the anti-air sign 2 can be detected is shortened, the anti-air sign 2 can be expected to be detected early, which is effective for early relief in the event of a disaster.

  Furthermore, the plane part 6 has a high reflectance and can be detected by photographing visible light from above, so that the anti-air sign 2 can be detected even in a visible light image photographed by the optical satellite 24.

  The height and thickness of the column part 4 of the anti-air sign 2 and the area of the plane part 6 are set so that the SAR satellite 22 and the optical satellite 24 can detect the anti-air sign 2. For example, the anti-air sign 2 can be detected by an X, C, and L band SAR satellite 22 with a ground sampled distance (GSD) of 3 m class, and can be detected by an optical satellite 24 with a GSD of 1 m class. Composed. In this case, the height of the column part 4 is about 1.5 to 2 m, the thickness is about 0.5 m, and when the plane part 6 is a square, one side thereof, and when it is a circle, the diameter is about 4 m each. can do.

  For the purpose of using the anti-air sign 2 as a rescue sign at the time of disaster, it is preferable that the anti-air sign 2 is temporarily installed in, for example, a schoolyard or a park when used, and can be stored when not in use. Therefore, in order to facilitate storage, the anti-air sign 2 can be separated from the column portion 4 and the plane portion 6 as described above, and can be folded by making the plane portion 6 from a flexible material. Yes. 5 and 6 are schematic views for explaining an example of the anti-air sign 2 that can be decomposed and made small when not in use, FIG. 5 is a schematic vertical sectional view of the anti-air sign 2 at the time of use, and FIG. It is a schematic vertical sectional view in use.

  This anti-air marking 2 can divide the cylinder constituting the column part 4 into a plurality of stages, and each part of the divided cylinder can be made into a cage structure to make it small. For example, the column part 4 of the anti-air marking 2 in FIG. 5 is divided into three stages of a lower part 40, a middle part 41, and an upper part 42. Each step is basically a cylinder, but the outer diameter of the middle step portion 41 is smaller than the inner diameter of the lower step portion 40, and the outer diameter of the upper step portion 42 is smaller than the inner diameter of the middle step portion 41. Thereby, when not in use, the inside step portion 41 is stored inside the lower step portion 40, and the upper step portion 42 is further stored inside the middle step portion 41, and the height can be made smaller than when used.

  In the example shown in FIGS. 5 and 6, the middle step portion 41 is formed on the upper end side of the lower step portion 40 so that the lower step portion 40, the middle step portion 41, and the upper step portion 42 can be simply stacked in order to form the column portion 4. A step 44 that is retracted inward is provided so that the lower end of the upper step portion 42 is placed. Similarly, a step 44 that is retracted inward is provided on the upper end side of the middle step portion 41 so that the lower end of the upper step portion 42 is placed. Further, a connecting portion 46 having an outer diameter smaller than the inner diameter of the middle step portion 41 is provided on the upper end side of the lower step portion 40, and similarly, a connecting portion 46 having an outer diameter smaller than the inner diameter of the upper step portion 42 is provided on the upper end side of the middle step portion 41. Is provided. When each step is stacked, each connecting portion 46 is inserted into a cylinder in the upper step, thereby preventing lateral displacement and dropping of the stacked middle step portion 41 and upper step portion 42.

  The stacked lower stage 40, middle stage 41, and upper stage 42 can be fixed by other means such as screws.

  The hollow in the cylinder which comprises the pillar part 4 can be utilized in order to accommodate the folded plane part 6 at the time of non-use. Thereby, the storage space of the anti-air sign 2 when not in use can be reduced. In the example shown in FIG. 6, a lump 48 in which the flat surface portion 6 is folded is housed in the inside of the pillar portion 4 that has been disassembled and put into a cage state, that is, in the space in the upper step portion 42. In this space, other parts and tools necessary for assembling the anti-air sign 2 can also be stored. For example, a peg 50 that fixes the flat surface portion 6 to the ground can also be stored.

  Now, as shown in FIG. 5, the plane part 6 is developed on the ground surface during use. For example, by injecting a liquid such as water into the frame portion 10 and inflating it, the frame portion 10 serves as a weight for making it difficult for the flat surface portion 6 to be turned up by wind or the like. Further, the expansion of the frame portion 10 can apply tension to the main portion 8 and increase the flatness of the main portion 8. In order to fix the flat portion 6, the tab 12 can be fixed to the ground surface 20 by driving in the peg 50 as already described.

  As the frame portion 10 expands, the edge of the flat portion 6 becomes higher than the inner region formed of the main portion 8. In this way, a liquid 52 such as water can be stored in a recess inside the flat portion 6 formed. The liquid surface is not affected by the unevenness of the ground surface 20 on which the flat part 6 is laid, and the flatness is increased and the scattering of microwaves is reduced compared to the case of the main part 8 alone. Since the total reflection on the liquid surface can be expected, this configuration is effective in securing the intensity of the reflected wave from the anti-air marker 2 to the SAR satellite 22.

  As described above, one surface of the flat portion 6 has a high reflectance such as white and is easily detected by visible light photographing from the sky, but the other surface has a lower reflectance than the one surface. It can also be a color that is difficult to detect in visible light photography from above. FIG. 7 is a schematic diagram for explaining the flat portion 6 having different colors on both sides. The state (a) shown on the left side of FIG. 7 is a perspective view of the flat portion 6 installed with the surface having high reflectance as the upper surface, and the state (b) shown on the right side is installed with the surface with low reflectance as the upper surface. It is a perspective view of the flat part 6 made. For example, the upper surface in the state of FIG. 7A can be white or yellow as described above. On the other hand, the upper surface in the state of (b) can be black or blue, for example. The arrows in both directions in the center of FIG. 7 indicate that it is possible to select which surface of the plane portion 6 is the upper surface when the anti-air sign 2 is installed.

  The SAR satellite 22 can basically detect the anti-air sign 2 equally even if the color of the upper surface of the plane portion 6 is different. On the other hand, in the visible light image of the optical satellite 24, the anti-air marker 2 in which the plane portion 6 is in the state of FIG. 7A is easy to detect, but the anti-air marker 2 in the state of FIG. Is difficult to detect. Therefore, by collating the detection result of the SAR satellite 22 with the image of the optical satellite 24, it is possible to distinguish and detect the anti-air sign 2 in two states. By pre-determining the contents of the marking for each of these two states, two meanings can be transmitted by the anti-air marking 2.

  It is also possible to arrange a plurality of the above-described anti-air signs 2 so that they can be distinguished from each other, and use the set as one anti-air sign. For example, different marking contents can be transmitted according to the number and arrangement pattern of the anti-air signs 2 constituting the anti-air sign group (the arrangement position of the anti-air signs, the orientation of the surface of the plane portion 6, and the combination thereof). FIG. 8 is a schematic plan view of an anti-air sign 60 composed of four anti-air signs 2. The anti-air marker 60 has a configuration in which the anti-air marker 2 is arranged in a 2 × 2 matrix. Each anti-air marker 2 constituting the anti-air marker 60 includes a plane portion 6 having different colors on both sides, and the anti-air marker 60 enables identification of the contents of the indication by a combination pattern of the plane directions of the plane portions 6. For example, 16 types of labeling contents are possible depending on the difference in brightness of the colors of the plane portions 6 of the four anti-air signs 2.

  If the anti-air sign 2 is not permanently installed, it will be installed in an emergency, so it may be overlooked if it is taken once in an emergency. For this reason, the installation location and installation location of the anti-air sign 2 are determined in advance, and the image of the state where it is not installed and the image of the state where it is installed are photographed in units of installation locations during normal times. In comparison with the observation image by the sign placement, the extraction accuracy of the anti-air sign 2 can be improved, so that early detection and early relief are possible.

  FIG. 9 is a schematic perspective view of the anti-air sign 2 showing another example of the pillar portion 4. In the above-described anti-air marking 2, the column part 4 is a cylinder, but a plurality of cylinders (three or more in the sense of a rotationally symmetric shape having an isotropic property relatively close to a circle) of the same thickness are used as their axes. Are preferably bundled so as to be arranged on the circumference. FIG. 9 shows a shape in which six cylinders 62 having the same thickness are bundled so that their axes are arranged on the circumference as an example of the column part 4. In FIG. 9, the cylinders are arranged on the circumference, and there are no cylinders inside. However, the cylinders may be arranged inside depending on the balance between the number of necessary cylinders and the installation strength against the crosswind. Is possible.

  In addition, when the anti-air marking 2 is permanently installed, the flat surface portion 6 does not need to be made of a flexible material. For example, the flat surface portion 6 is made of a material that is hard to be affected by the unevenness of the ground surface 20 and can easily ensure flatness. For example, the flat portion 6 can be made of a metal plate.

  2 Air markings, 4 pillars, 6 planes, 8 main parts, 10 frames, 12 tabs, 20 ground, 22, 22a, 22b SAR satellites, 24 optical satellites, 40 lower parts, 41 middle parts, 42 upper parts, 44 steps, 46 connections, 50 pegs, 60 anti-air signs, 62 cylinders.

Claims (3)

An anti-air sign for disaster areas that can be detected by synthetic aperture radar,
And the bar portion that will be erected perpendicular to the surface of the earth,
Before SL laid on the ground around the pillar portion, it consists of a flat portion having an upper surface that is orthogonal to the axis of the front Symbol pillar portion,
Surface and the upper surface of the planar portion of the front Symbol column portion is made of a material that reflects electromagnetic waves the synthetic aperture radar is transmitting,
Electromagnetic wave reflecting material provided on the plane portion is only pre-Symbol pillar portion,
Before SL pillar part cylindrical, or a plurality of shapes which a bundle of cylindrical, that is used for radio wave coming from all directions except directly above,
Anti-aircraft sign for disaster areas. In the anti-aircraft sign for disaster areas according to claim 1,
The said planar portion and front Symbol column portion are separable,
The flat portion is made of a flexible material and can be folded.
Before Symbol column portion can in cage placed is divided into a plurality of stages, and having a cavity capable of housing the flat portion which is folded in a state that said insertion cage structure,
Anti-aircraft sign for disaster areas. In the anti-aircraft sign for a disaster area according to any one of claims 1 and 2,
The plane part is
A sheet-shaped main part;
A frame portion provided at an edge of the main portion and surrounding the main portion;
Have
The frame part is inflated by injecting fluid, and the edge of the flat part is made higher than the inside;
Anti-aircraft sign for disaster areas.

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