JP2009217613A - Measurement system, buoy, receiver and measurement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology for preventing electric wave interference between a radio wave transmitted by a measuring buoy and a radio wave transmitted by another wireless equipment. <P>SOLUTION: This measurement system has: the buoy having a measurement instrument, and transmitting measurement information showing a measurement value of the measurement instrument by a radio wave whose orientation of horizontal directivity is controlled based on a transmission direction to which the radio wave is to be transmitted; and a receiver receiving the radio wave transmitted from the buoy to acquire the measurement information. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for acquiring measurement data from a measurement buoy.

A buoy that is dropped from an aircraft and collects measurement data indicating measurement values measured in water can transmit the measurement data by radio waves. This buoy assigns a radio frequency to each sensor in order to avoid interference between buoys when performing ocean measurements over a wide area. For this reason, when a large number of sensors are used, radio bands corresponding to the number of sensors to be used are used, but the radio frequency band is limited. In a limited frequency band, like the configuration disclosed in Patent Document 1, the buoy may be forced to transmit radio waves using the same frequency as the land radio equipment.
JP 7-191137 A

  However, in the configuration disclosed in Patent Document 1, since the buoy transmits radio waves in an omnidirectional manner in the horizontal direction, as shown in FIG. 15, the buoy radio waves dropped near the coast are directly transmitted to land radios. May also cause radio interference.

  In view of the above problems, an object of the present invention is to provide a technique for preventing radio wave interference between a radio wave transmitted by a measurement buoy and a radio wave transmitted by another radio.

  In order to achieve the above object, the measurement system of the present invention has a measuring instrument, and the measurement information indicating the measurement value of the measuring instrument is changed to the horizontal directivity direction based on the transmission direction in which the radio wave should be transmitted. A buoy that transmits with a controlled radio wave; and a receiver that receives the radio wave transmitted from the buoy and acquires the measurement information.

  The buoy of the present invention includes a measuring instrument and transmission means for transmitting measurement information indicating the measurement value of the measuring instrument using radio waves in which the directivity direction of horizontal directivity is controlled based on a transmission direction for transmitting radio waves. .

  The receiver of the present invention is a transmission means for transmitting azimuth information indicating a transmission direction in which radio waves are to be transmitted to the buoy, and a reception means for receiving a radio wave whose horizontal directivity is controlled from the buoy; Have

  In the measuring method of the present invention, a buoy having a measuring instrument transmits measurement information indicating the measurement value of the measuring instrument by radio waves in which the directivity direction of horizontal directivity is controlled based on the transmission direction in which the radio waves are to be transmitted, The radio wave is received by a receiver arranged at a position where the radio wave of which the directing direction is controlled can be received, and the measurement information is acquired.

  According to the present invention, the buoy transmits a radio wave in which the directivity of the horizontal directivity is controlled. Therefore, if the directivity direction is a direction that does not cause radio wave interference between its own transmission radio wave and other radio waves, the radio wave Interference can be prevented.

(First embodiment)
A first embodiment for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an overall view showing the configuration of the measurement system 1. The measurement system 1 is a system that performs underwater measurement by dropping a buoy for underwater measurement from an aircraft and receiving measurement information indicating a measurement value from the buoy. Referring to FIG. 1, the measurement system 1 includes an aircraft 10 and a buoy 20.

  The aircraft 10 drops the buoy 20 onto the water and wirelessly transmits azimuth information indicating the azimuth from the buoy 20 to a position within the radio wave reception range of the aircraft 10. Then, the aircraft 10 receives the measurement information transmitted by the buoy 20 and records the measurement value indicated by the measurement information. When the aircraft 10 receives a radio wave to which measurement information is added from the buoy 20, the aircraft 10 flies in an area where the radio wave interference is unlikely to occur between the radio wave and a radio wave from another wireless device (for example, at sea).

  In addition, not only an aircraft but a ship may drop the buoy 20 and transmit / receive radio waves to / from the buoy 20. Further, the transmission / reception of radio waves with the buoy 20 is not limited to an aircraft or a ship, but may be ground radio equipment.

  Furthermore, the aircraft or the like that transmits azimuth information to the buoy 20 and the aircraft or the like that receives measurement information from the buoy 20 need not be the same. If the aircraft 10 transmits the azimuth information and another aircraft or the like receives the measurement information, the azimuth indicated by the azimuth information is an azimuth to an aircraft or the like different from the aircraft 10. When there are a plurality of aircrafts or the like that can receive radio waves from the buoy 20 or when the range of radio waves received by the aircraft 10 is wide to some extent, the aircraft 10 will interfere with radio waves from other radios out of the directions to them. Select an azimuth that is unlikely to occur and transmit the azimuth. Whether the azimuth is less likely to cause radio wave interference depends on the distance from the position of the buoy 20 to the radio device where radio wave interference may occur, the transmission range of radio waves transmitted from the radio device, and the frequency band of the radio waves The aircraft 10 determines based on the above.

  The buoy 20 is dropped from the aircraft 10, decelerates with a parachute, etc., and lands. The buoy 20 has a floating part 21 and an underwater sensor 23. The floating portion 21 and the underwater sensor 23 are integrated when dropped and separated after landing. The flying portion 21 has an antenna 22 and a radio circuit 24. The floating portion 21 floats on the water surface such that the antenna 22 jumps to the water surface by obtaining buoyancy by spreading the float with carbon dioxide gas or the like.

  The antenna 22 is an array antenna, for example, and includes antenna elements 22A, 22B, 22C, and 22D. The antenna 22 receives direction information from the aircraft 10 and transmits a radio wave having horizontal directivity in a predetermined direction. The antenna elements 22A, 22B, 22C, and 22D are arranged so as to be perpendicular to the water surface when the floating portion 21 floats on the water surface.

  The configuration of the antenna 22 will be described with reference to FIG. This figure is a top view of the floating part 21. Referring to the figure, the buoy 20 has a circular shape when viewed from above when it floats on the water surface, and the antenna elements 22A, 22B, 22C, and 22D are equidistant from the center of the floating portion 21. , Are arranged at positions where their distances are equal. The radio circuit 24 gives a phase difference to each of the antenna elements 22A, 22B, 22C, and 22D to supply power, and changes the timing of radio wave transmission of each antenna element, so that the antenna 22 has directions A, B, C, and A radio wave having horizontal directivity in one of the four directions D is transmitted. The directions A, B, C, and D are directions from the center of the flying portion 21 to the antenna elements 22A, 22B, 22C, and 22D, respectively. Moreover, the antenna 22 transmits omnidirectional radio waves in the horizontal direction by supplying power without giving a phase difference. In the figure, a one-dot chain line indicates a transmission range of a radio wave transmitted from each antenna element.

  In this embodiment, four antenna elements are provided. However, the number of antenna elements and the type of antenna are not limited as long as radio wave transmission can be performed by switching the horizontal directivity in a plurality of directions. In addition, the azimuth for providing horizontal directivity is not limited to four directions, and transmission may be performed by switching to two azimuths or eight azimuths by adjusting the type of antenna, the number of antenna elements, or the phase difference.

  Returning to FIG. 1, the underwater sensor 23 includes one or more measuring devices such as a temperature sensor, a sonar, and a pressure gauge, and measures a water temperature, a position of a school of fish, a water pressure, and the like. Then, the underwater sensor 23 transmits measurement information indicating the measurement value to the wireless circuit 24.

  Note that the buoy 20 may have a configuration that includes a sensor for measuring temperature, wind speed, and the like on the water in addition to the underwater sensor 23.

  The radio circuit 24 receives the measurement information from the underwater sensor 23, and transmits the measurement information to the antenna 22 using radio waves whose horizontal directivity is controlled toward a predetermined direction.

  The configuration of the radio circuit 24 will be described in detail with reference to FIG. FIG. 2 is a block diagram showing the configuration of the radio circuit 24. Referring to the figure, the radio circuit 24 includes a receiving unit 241 and a transmitting unit 243. The receiving unit 241 receives the measurement information 2411 from the underwater sensor 23, receives the azimuth information 2412 from the aircraft 10 via the antenna 22, and stores these pieces of information.

  The transmission unit 243 includes an azimuth selection unit 2431 and a directivity circuit 2432. The azimuth selection unit 2431 selects an azimuth having the smallest angle difference from the azimuth indicated by the azimuth information 2412 among the candidate azimuths A, B, C, and D that give the horizontal directivity. Specifically, the azimuth | direction selection part 2431 acquires any absolute azimuth | direction (for example, any azimuth | direction of the east, west, south, and north) from the buoy 20 with a azimuth magnet. The azimuth selection unit 2431 determines a reference azimuth fixed with respect to the buoy 20 in advance, and obtains an angle of the reference azimuth with respect to the acquired absolute azimuth. The reference azimuth is, for example, azimuth A. The azimuth selection unit 2431 selects an azimuth having the smallest angle difference from the azimuth indicated by the azimuth information 2412 among the azimuths A, B, C, or D corrected with the obtained angle.

  For example, as shown in FIG. 4A, when the angle between the reference azimuth (azimuth A) and the north absolute azimuth is 0 degrees, the azimuths A, B, C, and D corrected by this angle are North, east, south, and west orientations, respectively. Here, when azimuth information indicating the north azimuth is received, the azimuth selection unit 2431 selects the azimuth A that minimizes the angular difference from the north azimuth.

  Next, as shown in FIG. 4 (b), a case is considered in which the buoy 20 on the water rotates 90 degrees counterclockwise from the state of FIG. . In this case, the angle of the north absolute azimuth with respect to the reference azimuth (azimuth A) is 90 degrees, and the azimuths A, B, C, and D corrected by this angle are the west, north, east, and south azimuths, respectively. It becomes. Here, when azimuth information indicating the west azimuth is received, the azimuth selection unit 2431 selects the azimuth A that minimizes the angular difference from the west azimuth.

  The directivity circuit 2432 supplies phase difference power to the antenna 22 so that a radio wave having directivity in the direction selected by the direction selection unit 2431 is transmitted. The transmission unit 243 transmits the measurement information 2411 by radio waves.

  Thus, the radio circuit 24 receives the direction information 2412 from the aircraft 10 via the antenna 22 and receives the measurement information 2411 from the underwater sensor 23. The radio circuit 24 selects the azimuth closest to the azimuth indicated by the azimuth information 2412 from the azimuths A, B, C, and D, and adds the measurement information 2411 to the selected azimuth. Transmits radio waves with controlled.

  Next, the operation of the wireless circuit of this embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing the operation of the radio circuit 24. When the wireless circuit 24 lands and power is supplied from a battery (not shown) built in the buoy 20 or the like, the wireless circuit 24 starts the operation shown in FIG. Referring to the figure, the receiving unit 241 receives measurement information 2411 from the underwater sensor 23 (step S5). The receiving unit 241 receives the direction information 2412 from the aircraft 10 (step S10). The azimuth selection unit 2431 obtains the absolute azimuth and the rotation angle of the buoy 20 from the reference position (step S15). The azimuth selection unit 2431 selects the azimuth having the smallest angle difference from the azimuth indicated by the azimuth information 2412 among the azimuths A, B, C, and D from the absolute azimuth and the rotation angle (step S20). The directivity circuit 2432 supplies phase difference power so that a radio wave having horizontal directivity in the direction selected in step S15 is transmitted. The transmission unit 243 transmits the measurement information 2411 by radio waves (step S25). After step S25, the radio circuit 24 ends the operation. The aircraft 10 receives and acquires the measurement information 2411 transmitted from the buoy 20.

  With reference to FIG. 6, the operation example of the measurement system 1 of this embodiment is demonstrated. Referring to the figure, the aircraft 10 that dropped the buoy 20 is flying, for example, in a region in the west direction as viewed from the buoy 20. On the other hand, a ground radio equipment 30 is installed in the east direction as viewed from the buoy 20. The frequency band of the radio wave transmitted by the wireless facility 30 is close to the frequency band of the radio wave transmitted by the buoy 20, and these radio waves may interfere with each other.

  Therefore, the aircraft 10 transmits azimuth information indicating the west direction from the buoy 20 to the buoy 20. The buoy 20 receives the azimuth information (step S10), and transmits a radio wave whose horizontal directivity is controlled toward the azimuth (for example, the azimuth A) that has the smallest angular difference from the west azimuth indicated by the azimuth information (step S25). ).

  Since the radio wave transmitted by the buoy 20 has horizontal directivity in the west direction, the measurement system 1 can avoid interference between the radio wave and the radio wave transmitted by the radio equipment 30 in the east direction.

  As described above, according to the present embodiment, when the buoy 20 wirelessly transmits the measurement information 2411, the buoy 20 controls the horizontal directivity direction and transmits the radio wave. If the direction is such that there is no radio wave interference with other radio waves, radio wave interference can be prevented.

  In addition, the buoy 20 controls the horizontal directivity direction based on the direction information 2431 received from the aircraft 10, so that it is not necessary to obtain the direction in which radio waves should be transmitted.

  The buoy 20 controls the horizontal directivity direction based on the angle of its own reference azimuth with respect to the absolute azimuth and the azimuth indicated by the azimuth information 2414. Therefore, even when the buoy 20 rotates, radio wave interference does not occur. Radio waves can be transmitted so as not to occur.

  Since the azimuth indicated by the azimuth information 2414 is an azimuth that does not cause radio wave interference, the aircraft 10 can perform measurement while preventing radio wave interference.

  Since the azimuth indicated by the azimuth information 2414 is the azimuth from the buoy 20 to the aircraft 10, the aircraft 10 can receive radio waves from the buoy 20 and acquire measurement information 2412.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is an overall view showing the configuration of the radio circuit 24a of the second embodiment. Referring to the figure, the radio circuit 24 does not have the azimuth information 2412 but has the map information 245 and the GPS (Global Positioning System) 247 as compared with the radio circuit 24 of the first embodiment. The second embodiment differs from the first embodiment in that the buoy 20 does not receive the direction information 2412 and has the map information 245 and the GPS 247. Other configurations of the measurement system of the second embodiment are the same as those of the first embodiment.

  The map information 245 is information indicating a map around the area where the buoy 20 is dropped. The map information 245 is a radio wave of the radio equipment (30) that transmits a radio wave that may interfere with the radio wave transmitted by the buoy 20. Includes information indicating the transmission range of.

  The GPS 247 acquires the current position where the buoy 20 is floating. For example, the GPS 247 transmits / receives radio waves to / from a plurality of satellites in orbit, performs three-dimensional positioning based on the difference in transmission / reception time, and obtains the current position.

  The azimuth selection unit 2431 selects (determines) one of the azimuths A, B, C, and D that does not interfere with radio waves transmitted by itself and radio waves from other wireless equipment. For example, the direction in which the radio wave transmitted from the current position of the buoy 20 does not overlap the transmission range of the transmission radio wave of another wireless facility is obtained.

  FIG. 8 is a flowchart showing the operation of the radio circuit 24a of this embodiment. Referring to the figure, after receiving the measurement information 2411 (step S5), the radio circuit 24a reads the transmission range of the transmission radio wave of the other radio equipment 30 from the map information 245 (step S11). Subsequently, the GPS 247 acquires the current position where the buoy 20 is floating (step S13). The azimuth selection unit 2431 obtains the absolute azimuth and the rotation angle of the buoy 20 from the reference position (step S15). From the results obtained in steps S11, S13, and S15, the azimuth selection unit 2431 has radio wave interference between the transmission radio wave of the buoy 20 and the transmission radio wave of the radio equipment 30 among the azimuths A, B, C, and D. An orientation that does not occur is selected (step S20a). The directivity circuit 2432 supplies phase difference power so that the direction selected in step S20a has directivity. The transmission unit 243 transmits the radio wave added with the measurement information 2411 (step S25). After step S25, the radio circuit 24a ends the operation.

  As described above, according to the present embodiment, the buoy 20 acquires its current position and transmits a radio wave having horizontal directivity in a direction that avoids radio wave interference with the transmission radio wave of the other radio equipment 30. To do. For this reason, the buoy 20 can transmit a radio wave in a direction where radio wave interference with the radio wave from the radio equipment 30 does not occur without receiving the direction information 2412.

  In the present embodiment, the buoy 20 may be configured to obtain a direction in which radio wave interference does not occur by receiving the map information 245 and the drop position of the buoy 20 from the aircraft 10.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. The configuration of the communication system according to the present embodiment instructs the buoy 20 to transmit non-directional radio waves when there is no possibility that the aircraft 10 interferes with radio waves from the buoy 20 and radio waves from the radio equipment 30. It is the same as that of 1st Embodiment except transmitting non-directional instruction information. This embodiment is different from the first embodiment in that the aircraft 10 instructs the buoy 20 to transmit non-directional radio waves when there is no possibility of radio wave interference.

  For example, the aircraft 10 has the map information 245 and the GPS 247 shown in FIG. 7, and determines the presence or absence of radio wave interference based on the drop position of the buoy 20 and the transmission range of the radio equipment 30. In addition, the buoy 20 has a GPS and transmits its own position information to the aircraft 10, and the aircraft 10 may determine the presence or absence of radio wave interference based on the received current position and the transmission range of the radio equipment 30. .

  FIG. 9 is a block diagram showing a configuration of the radio circuit 24b of the present embodiment. Referring to the figure, the configuration of the wireless circuit 24b of this embodiment is the same as that of the first embodiment except that the receiving unit 241 further receives omnidirectional instruction information 2413 that instructs omnidirectional radio wave transmission. It is the same.

  FIG. 10 is a flowchart showing the operation of the radio circuit 24b of this embodiment. Referring to the figure, the operation of the radio circuit 24b of the present embodiment is the same as that of the first embodiment except that steps S7 and S27 are executed.

  After receiving the measurement information 2411 (step S5), the radio circuit 24b determines whether omnidirectional instruction information 2413 is received from the aircraft 10 via the antenna 22 (step S7). If the omnidirectional instruction information 2413 has not been received (step S7: NO), the radio circuit 24b executes step S10. If the omnidirectional instruction information 2413 has been received (step S7: YES), the transmission unit 243 transmits radio waves that are nondirectional in the horizontal direction and to which the measurement information 2411 is added (step S27). After step S27, the radio circuit 24b ends the operation.

  As described above, according to the present embodiment, if there is no possibility of radio wave interference, the aircraft 10 causes the buoy 20 to transmit radio waves in a non-directional manner, so that the measurement information 2411 can be easily received.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIGS. The aircraft 10 can cause the buoy 20 to transmit radio waves having not only horizontal directivity but also vertical directivity. The third embodiment is different from the first embodiment in that the aircraft 10 transmits radio waves having horizontal directivity or vertical directivity to the buoy 20.

  The configuration of the measurement system of this embodiment is the same as that of the first embodiment, except that the aircraft 10 further transmits vertical directivity instruction information that instructs transmission of radio waves having vertical directivity.

  For example, as shown in FIG. 11, when the aircraft 10 flies over the radio equipment 30 on land, radio interference may occur even if the buoy 20 transmits a radio wave having horizontal directivity to the aircraft 10. . Therefore, the aircraft 10 causes the buoy 20 to transmit radio waves having vertical directivity if radio wave interference can occur when radio waves having horizontal directivity are transmitted.

  FIG. 12 is a block diagram showing a configuration of the radio circuit 24c of this embodiment. Referring to the figure, the configuration of the radio circuit 24c of this embodiment is the same as that of the first embodiment except that the receiving unit 241 further receives vertical directivity instruction information 2414 that instructs radio wave transmission having vertical directivity. It is the same.

  FIG. 13A is a side view showing a transmission range of radio waves transmitted by the buoy 20 when the azimuth information 2412 is received and the vertical directivity instruction information 2414 is not received. As shown in FIG. 2A, the buoy 20 transmits radio waves that are non-directional in the vertical direction and have only directivity in the horizontal direction. FIG. 12B is a side view showing the transmission range of the radio wave transmitted by the buoy 20 when the vertical directivity instruction information 2414 is received. As shown in FIG. 2B, the buoy 20 transmits a radio wave having directivity in the vertical direction. At this time, the buoy 20 may transmit a non-directional radio wave in the horizontal direction, or may further receive the azimuth information 2412 and transmit a radio wave having horizontal directivity and vertical directivity.

  FIG. 13 is a flowchart showing the operation of the radio circuit 24c of this embodiment. Referring to the figure, the operation of the radio circuit 24c of the present embodiment is the same as the operation of the radio circuit 24 of the first embodiment shown in FIG. 5 except that steps S9 and S31 are further executed.

  After receiving the measurement information 2411 (step S5), the radio circuit 24c determines whether or not the vertical directivity instruction information 2414 is received from the aircraft 10 (step S9). If the vertical directivity instruction information 2414 has not been received (step S9: NO), the radio circuit 24 executes step S10. If the vertical directivity instruction information 2414 has been received (step S9: YES), the directivity circuit 2432 supplies phase difference power so as to have vertical directivity, and the transmission unit 243 transmits radio waves with measurement information 2411 added thereto. (Step S31). After step S31, the radio circuit 24c ends the operation.

  According to the present embodiment, since the aircraft 10 can cause the buoy 20 to transmit radio waves having horizontal directivity or vertical directivity, the radio waves can be transmitted even when the aircraft 10 flies over radio equipment on land. Interference can be reliably prevented.

  All or part of the processes shown in FIGS. 5, 8, 10, and 14 can also be realized by a computer executing a software program.

1 is an overall view illustrating a configuration of a measurement system according to a first embodiment. It is a top view of the buoy of a 1st Example. It is a block diagram which shows the structure of the radio | wireless circuit of 1st Embodiment. (A) It is a top view of the buoy of a 1st Example. (B) It is a top view of the buoy of a 1st Example. It is a flowchart which shows operation | movement of the radio | wireless circuit of 1st Embodiment. It is a figure which shows the operation example of the measurement system of 1st Embodiment. It is a block diagram which shows the structure of the radio | wireless circuit of 2nd Embodiment. It is a flowchart which shows operation | movement of the radio | wireless circuit of 2nd Embodiment. It is a block diagram which shows the structure of the radio | wireless circuit of 3rd Embodiment. It is a flowchart which shows operation | movement of the radio | wireless circuit of 3rd Embodiment. It is a general view which shows the structure of the measurement system of 4th Embodiment. It is a flowchart which shows operation | movement of the radio | wireless circuit of 4th Embodiment. (A) It is a figure which shows the directivity of the transmission electromagnetic wave of the buoy of 4th Embodiment.

(B) It is a figure which shows the directivity of the transmission electric wave of the buoy of 4th Embodiment.
It is a flowchart which shows operation | movement of the radio | wireless circuit of 4th Embodiment. It is a general view which shows the structure of the conventional measurement system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Measurement system 10 Aircraft 20 Buoy 21 Floating part 22 Antenna 23 Underwater sensor 24, 24a, 24b, 24c Radio circuit 30 Radio equipment 31 Radio equipment 22A, 22B, 22C, 22D Antenna element 241 Transmitter 243 Receiver 245 Map information 247 GPS
2411 Measurement information 2412 Direction information 2413 Non-directional instruction information 2414 Vertical directivity instruction information 2431 Direction selection unit 2432 Directional circuit

Claims (18)

A buoy having a measuring instrument and transmitting measurement information indicating a measurement value of the measuring instrument with radio waves in which a directivity direction of horizontal directivity is controlled based on a transmission direction in which the radio waves are to be transmitted;
A receiver that receives the radio wave transmitted from the buoy and obtains the measurement information;
Measuring system.   2. The measurement system according to claim 1, wherein the buoy uses the candidate having the smallest angle difference from the transmission azimuth among a plurality of azimuth candidates as the directional direction of the horizontal directivity.   The measurement according to claim 1 or 2, wherein the buoy receives azimuth information indicating the transmission azimuth, and controls the directional direction of the horizontal directivity based on the transmission azimuth indicated in the received azimuth information. system.   The measurement system according to claim 3, wherein the receiver transmits the azimuth information to the buoy.   The buoy acquires an absolute azimuth, and controls the directional direction of the horizontal directivity based on an angle of its reference azimuth with respect to the acquired absolute azimuth and the transmission azimuth. The measurement system according to item.   The buoy stores transmission range information indicating the transmission range of radio waves of other wireless devices in advance, acquires its current position, and indicates the acquired current position and the stored transmission range information. The measurement system according to claim 1, wherein the transmission direction is determined based on the transmission range.   The measurement system according to any one of claims 1 to 6, wherein the transmission azimuth is an azimuth in which the radio wave transmitted by the buoy and a radio wave transmitted by another wireless device do not interfere with each other.   The measurement system according to claim 7, wherein the transmission azimuth is an azimuth from the buoy to a position within a radio wave reception range of the receiver. Measuring instruments,
Transmitting means for transmitting measurement information indicating the measurement value of the measuring instrument using radio waves in which the directivity direction of horizontal directivity is controlled based on a transmission direction for transmitting radio waves;
Buoy with.   10. The buoy according to claim 9, wherein the transmission unit sets the candidate having the smallest angle difference from the transmission direction among a plurality of azimuth candidates as the directional direction of the horizontal directivity. Further comprising receiving means for receiving azimuth information indicating the transmission azimuth;
The buoy according to claim 9 or 10, wherein the transmission means controls the directional direction of the horizontal directivity based on the transmission azimuth indicated in the received azimuth information. It further has an absolute azimuth obtaining means for obtaining an absolute azimuth,
The transmission unit controls the directivity direction of the horizontal directivity based on the angle of the transmission azimuth with respect to the absolute azimuth acquired by the absolute azimuth acquisition unit and the angle of its own reference azimuth with respect to the absolute azimuth. A buoy according to any one of claims 9 to 11. Storage means for storing transmission range information indicating the transmission range of radio waves of other wireless devices;
Current position acquisition means for acquiring its current position;
Further comprising
The transmission means acquires the transmission direction based on the current position acquired by the current position acquisition means and the transmission range indicated by the transmission range information read from the storage means. The buoy according to any one of the above.   The buoy according to any one of claims 9 to 13, wherein the transmission azimuth is an azimuth in which the radio wave transmitted by the buoy and a radio wave transmitted by another wireless device do not interfere with each other. A transmission means for transmitting azimuth information indicating a transmission azimuth to transmit radio waves to the buoy;
Receiving means for receiving a radio wave whose horizontal directivity is controlled from the buoy;
Having a receiver.   The receiver according to claim 15, wherein the transmission azimuth is an azimuth in which the radio wave transmitted by the buoy and a radio wave transmitted by another wireless device do not interfere with each other.   The receiver according to claim 16, wherein the transmission azimuth is an azimuth from the buoy to a position within a radio wave reception range of the receiver. A buoy having a measuring instrument transmits measurement information indicating the measurement value of the measuring instrument using radio waves in which the directivity direction of horizontal directivity is controlled based on the transmission direction in which the radio waves are to be transmitted,
A measurement method of receiving the radio wave and acquiring the measurement information by a receiver arranged at a position where the radio wave of which direction is controlled can be received.

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