Obstacle search method and apparatus in satellite communication system

Abstract

To estimate in real time the positions of obstacles existing in the space between a satellite and a ground station using at least one of the satellite and the ground station.SOLUTION: An apparatus searches for an obstacle O between a satellite and the ground in a satellite communication system consisting of the at least one satellite S1 orbiting in orbit and a plurality of ground stations. The apparatus includes a wireless communication unit 102 that, in response to at least one of the satellite or the ground stations transmits a search radio wave 110, receives a reflected wave R10 of the search radio wave, and a processing unit 103 that controls the wireless communication unit and estimates the position of the obstacle based on information on the reflected wave.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a satellite communication system, and more particularly to a technique for searching for obstacles between an orbiting satellite and a ground station. [Background technology]

[0002] Generally, wireless communication can widen the transmission band by using a high frequency band, but the tendency of radio waves to travel in a straight line increases. For this reason, for example, if there is an obstacle in the line of sight between a non-geostationary satellite and a ground station, problems such as deterioration of communication quality and communication disconnection may occur. In order to avoid communication failure, Patent Document 1 discloses a method of switching the communication path to another satellite when an obstacle is detected.

[0003] According to Patent Document 1, a terrestrial satellite communication device detects the presence of an obstacle such as a building by detecting a sudden drop in the reception level from the satellite. By recording the direction and time of the drop in reception level caused by the movement of the satellite, it is possible to estimate the direction of the obstacle as seen from the satellite communication device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-053665 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned Patent Document 1, a satellite communication device on the ground side estimates the direction of an obstacle by acquiring the position of the satellite in orbit and the timing of the drop in the reception level from the satellite. In other words, not only is satellite orbit information required, but a transmitting device and a receiving device are also required on the satellite side and on the ground side to estimate the obstacle.

[0006] According to Patent Document 1, the location of obstacles such as the surrounding terrain and buildings is estimated based on radio waves received from the satellite, with the location where the satellite communication device is installed as the center. Therefore, it is not possible to estimate in real time the location of moving obstacles such as aircraft flying above the satellite communication device or debris in space.

[0007] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an obstacle search method and apparatus, and a satellite communication system, which are capable of estimating in real time the position of an obstacle existing in the space between a satellite and a ground station by at least one of them. [Means for solving the problem]

[0008] The obstacle search device of the present disclosure is a device that searches for obstacles between at least one satellite orbiting in a satellite communication system consisting of the satellite and a plurality of ground stations, and at least one of the satellite or the ground station includes a wireless communication unit that transmits search radio waves and receives reflected waves of the search radio waves, and a processing unit that controls the wireless communication unit and estimates the position of the obstacle based on information on the reflected waves. The obstacle search method disclosed herein is a method for searching for obstacles between at least one satellite orbiting in a satellite communication system consisting of the satellite and a plurality of ground stations, in which a wireless communication unit transmits search radio waves and receives reflected waves of the search radio waves, and a processing unit controls the wireless communication unit to estimate the position of the obstacle based on information on the reflected waves. In the present disclosure, there is provided a satellite communication system consisting of at least one satellite orbiting in orbit and a plurality of ground stations, wherein the satellite includes a wireless communication unit that transmits search radio waves and receives reflected waves of the search radio waves, and a processing unit that controls the wireless communication unit and estimates the position of the obstacle based on information on the reflected waves. Effect of the Invention

[0009] According to the present invention, the position of an obstacle existing in the space between a satellite and / or a ground station can be estimated in real time. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram illustrating a schematic configuration of a satellite including an obstacle search device according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a block diagram illustrating a schematic configuration of a satellite including an obstacle search device according to a first example of the present disclosure. [Diagram 3] FIG. 3 is a block diagram illustrating a schematic configuration of a satellite including an obstacle search device according to a second example of the present disclosure. [Figure 4] FIG. 4 is a schematic diagram showing an example of search radio wave irradiation of an obstacle search device according to a third example of the present disclosure. [Diagram 5] FIG. 5 is a flow chart illustrating an example of an obstacle searching method according to the present disclosure. [Figure 6] FIG. 6 is a schematic diagram showing an example of a method for avoiding an obstacle estimated by the obstacle search method according to the present disclosure. [Figure 7] FIG. 7 is a network configuration diagram illustrating a schematic configuration of a satellite communication system according to the second embodiment of the present disclosure. [Figure 8] FIG. 8 is a block diagram illustrating a schematic configuration of a satellite including an obstacle search device in a satellite communication system according to the second embodiment of the present disclosure. [Figure 9] FIG. 9 is a sequence diagram showing an example of an obstacle search method in a satellite communication system according to the second embodiment of the present disclosure. [Figure 10] FIG. 10 is a block diagram illustrating a schematic configuration of a ground station including an obstacle search device according to the third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Overview of the embodiment> According to the present disclosure, at least one of the satellite and the ground station transmits a search radio wave and estimates the position of an obstacle based on information on the reflected wave. For example, the presence and position of an obstacle can be estimated based on the reception level and direction of the reflected wave. The search radio wave may be transmitted by multiple antennas, and each reflected wave may be received by multiple antennas. By using the reflected wave information of the search radio wave, the position of an obstacle between the satellite and the ground station can be estimated in real time.

[0012] More specific communication control will be described in detail below with reference to the drawings. However, the components described in the following embodiments are merely examples, and are not intended to limit the technical scope of the present invention.

[0013] 1. First embodiment 1.1) System configuration As shown in Fig. 1, the satellite S1 has a transmitting / receiving antenna 101 and a wireless communication unit 102. The transmitting / receiving antenna 101 may be provided as a separate transmitting antenna and a receiving antenna, or may serve as both a transmitting antenna and a receiving antenna. In this embodiment, the transmitting / receiving antenna 101 can control the directionality by using a phased array antenna. Search radio waves 110 having multiple irradiation ranges can be irradiated by using multiple phased array antennas.

[0014] When the transmitting / receiving antenna 101 serves as both a transmitting antenna and a receiving antenna, the transmitting mode and the receiving mode can be switched by the wireless communication unit 102. The directivity of the transmitting / receiving antenna 101 can be changed, and furthermore, a null point can be formed in a desired direction within the beam, and the beam diameter can be controlled by increasing or decreasing the number of antenna elements used.

[0015] The wireless communication unit 102 is capable of communicating with a ground station, transmitting search radio waves, and receiving reflected waves through the transmitting / receiving antenna 101. Note that the transmitting / receiving antenna 101 may be provided with an antenna for communicating with a ground station, an antenna for transmitting search radio waves, and an antenna for receiving reflected waves separately. By providing one or more dedicated search antennas separately from the communication antennas, the position of an obstacle can be estimated more accurately.

[0016] Furthermore, the satellite S1 has a processor unit 103 and a program memory 104, and the processor unit 103 is a processing unit that controls the operation of this embodiment. The processor unit 103 is composed of one or more processors. The processor unit 103 executes a program stored in the program memory 104 to realize the functions of a search control unit 105, an obstacle position estimation unit 106, a countermeasure selection unit 107, and a control unit 108.

[0017] The search control unit 105 controls the wireless communication unit 102 to radiate search radio waves 110 in a desired irradiation range from the transmitting / receiving antenna 101 at a desired timing. It is desirable to notify other satellites of the search start timing (search radio wave transmission time) before radiating the search radio waves. There may also be cases where the own search radio waves 110 or other search radio waves are reflected by an obstacle O, and the reflected waves R10 are received by the transmitting / receiving antenna 101. The search control unit 105 can process not only the own search radio waves 110 but also the reflected waves R10 of other search radio waves. Hereinafter, radio waves reflected or scattered in any direction by an obstacle O will be collectively referred to as reflected waves.

[0018] Note that objects with various physical properties are assumed as obstacles O that move through space. For example, space debris moves in space (here, at an altitude of 100 km or more) at a speed of up to 28,800 km per hour, has various sizes, and completely reflects or absorbs / scatters radio waves. Airplanes and high altitude platforms (HAPS) move above the ground (troposphere, lower stratosphere) at a speed of up to 100 to 800 km per hour, are about 60 to 100 m in size, and have the physical property of reflecting or scattering radio waves. Furthermore, rain clouds move above the ground (troposphere) at a speed of up to 50 km per hour, have various sizes, and have the physical property of attenuating radio wave intensity and transmitting it (radio wave attenuation).

[0019] If the obstacle O is a radio wave reflective object, the irradiated search radio wave 110 is reflected by the obstacle O and returns to the transmitting / receiving antenna 101. However, depending on the type of obstacle, the search radio wave 110 may be scattered in a different direction. Therefore, there is a possibility that the search radio wave of another satellite may be scattered by the obstacle and reach the transmitting / receiving antenna 101 of the satellite S1.

[0020] The obstacle position estimation unit 106 estimates the position of the obstacle O from the reflected wave information of each search radio wave. For example, the position of the obstacle O, that is, the distance and direction from the satellite S1, can be estimated using the reception level, reception direction, and reception time of the reflected waves received by different transmitting and receiving antennas.

[0021] The countermeasure selection unit 107 can perform processing such as changing the direction of the transmitted beam, changing the beam diameter, changing the frequency or frequency band, selectively suppressing the transmitted beam intensity, and increasing the transmitted beam intensity as countermeasures to avoid obstacles caused by the estimated obstacle O.

[0022] The obstacle search device according to this embodiment comprises a transmitting / receiving antenna 101, a wireless communication unit 102, and a processor unit 103. The specific functions of the processor unit 103 will be described later. Note that the obstacle search device according to this embodiment is mounted on a satellite, but is not limited to this, and the same applies if mounted on a ground station. An example of the configuration of a satellite S1 will be described below.

[0023] <Example 1> As shown in Fig. 2, satellite S2 has two transmitting / receiving antennas 201A and 201B and a wireless communication unit 202. The transmitting / receiving antennas 201A and 201B are arranged at a predetermined distance apart and can radiate search radio waves in different directions. The wireless communication unit 202 includes a transceiver 202A and a search transceiver 202B, which are connected to the transmitting / receiving antennas 201A and 201B, respectively. Here, the transmitting / receiving antenna 201A and the transceiver 202A are provided for communication with a ground station, and the transmitting / receiving antenna 201B and the search transceiver 202B are provided for searching for obstacles.

[0024] The satellite S2 further has a processor unit 203 and a program memory 204, and the processor unit 203 is a processing unit that controls the operation of this embodiment. The processor unit 203 is composed of one or more processors. The processor unit 203 has the same functions as the processor unit 103 in Fig. 1, and by executing a program stored in the program memory 204, it realizes the functions of a search control unit 205, an obstacle position estimation unit 206, a countermeasure selection unit 207, and a control unit 208.

[0025] The search control unit 205 controls the wireless communication unit 202 to radiate search radio waves 210A and 210B in a desired irradiation range from the transmitting / receiving antennas 201A and 201B at a desired timing. When the transmitting / receiving antennas 201A and 201B radiate the search radio waves 210A and 210B simultaneously, it is necessary to identify each search radio wave by an identification index such as a frequency used or an identification code. This allows the search control unit 205 to distinguish and receive the reflected waves R21 and R22 reflected by the obstacle O from the search radio waves 210A and 210B, and generate reflected wave information for each.

[0026] An obstacle position estimation unit 206 estimates the position of an obstacle O from the reflected wave information of each search radio wave, and a countermeasure selection unit 207 uses the estimated position of the obstacle O to execute countermeasures to avoid the obstacle.

[0027] <Second Example> As shown in Fig. 3, satellite S3 has three transmitting / receiving antennas 301A, 301B, and 301C and a wireless communication unit 302. The transmitting / receiving antennas 301A, 301B, and 301C are arranged at a predetermined distance from each other, and can emit search radio waves of different irradiation ranges. Here, the transmitting / receiving antenna 301A is an antenna for communication with a ground station, the transmitting / receiving antenna 301B is a wide-area search antenna, and the transmitting / receiving antenna 301C is a narrow-area search antenna. The wireless communication unit 302 can emit search radio waves 310A, 310B, and 310C, respectively, using the transmitting / receiving antennas 301A, 301B, and 301C.

[0028] The satellite S3 further has a processor unit 303 and a program memory 304, and the processor unit 303 is a processing unit that controls the operation of this embodiment. The processor unit 303 is composed of one or more processors. The processor unit 303 has the same functions as the processor unit 103 in Fig. 1, and by executing a program stored in the program memory 304, it realizes the functions of a search control unit 305, an obstacle position estimation unit 306, a countermeasure selection unit 307, and a control unit 308.

[0029] The search control unit 305 can control the wireless communication unit 302 to radiate search radio waves 310A, 310B and 310C within the respective radiation ranges from the transmitting / receiving antennas 301A, 301B and 301C at desired timing.

[0030] As will be described in detail later, a search method is desirable for the satellite S3 to first perform a rough search using a wide-area antenna, and then narrow down the obstacle position using a narrow-area antenna. For example, a wide-area search radio wave 310B with a wide irradiation range is emitted from the transmitting / receiving antenna 301B (hereinafter referred to as the wide-area search antenna 301B), and a reflected wave R32 is detected by the transmitting / receiving antenna 301B (or all transmitting / receiving antennas). If the presence of an obstacle O is determined by this wide-area search, search radio waves 310A and 310C are emitted in the direction in which the obstacle O exists. In other words, a search radio wave 310A for communication and a narrow-area search radio wave 310C with a narrower irradiation range than the wide-area search radio wave 310B are emitted. By detecting the reflected waves R31 and R33, the position of the obstacle O can be estimated more accurately.

[0031] When the search radio waves 310A and 310C are radiated simultaneously from the communication antenna 301A and the narrow-area search antenna 301C, it is necessary to identify each search radio wave by an identification indicator such as a frequency used or an identification code. This allows the search control unit 305 to distinguish and receive the reflected waves R31 and R33 that are reflected by the obstacle O from the search radio waves 310A and 310C, and generate reflected wave information for each.

[0032] An obstacle position estimation unit 306 estimates the position of an obstacle O from the reflected wave information of each search radio wave, and a countermeasure selection unit 307 uses the estimated position of the obstacle O to execute a countermeasure to avoid the obstacle.

[0033] <Example 3> As shown in Fig. 4, the wireless communication unit 302 in Fig. 3 may further be provided with a transmitting / receiving antenna 301D (hereinafter, referred to as narrow area search antenna 301D). That is, in addition to the wide area search antenna 301B and the narrow area search antenna 301C, the narrow area search antenna 301D is provided at a predetermined position. In this third example, the basic configuration of the wireless communication unit 302 and the processor unit 303 is the same as in the second example, and therefore is omitted in Fig. 4.

[0034] The search method is basically the same as the second example. That is, first, a search radio wave 310B with a wide irradiation range is emitted from the wide-area search antenna 301B, and a reflected wave R32 is detected by the wide-area search antenna 301B (or all transmitting and receiving antennas). If the wide-area search determines that an obstacle O exists, search radio waves 310A, 310C, and 310D are emitted in the direction in which the obstacle O exists. That is, a search radio wave 310A for communication and narrow-area search radio waves 310C and 310D with a narrower irradiation range than the wide-area search radio wave 310B are emitted. By detecting the reflected waves R31, R33, and R34, the position of the obstacle O can be estimated more accurately.

[0035] In the third example illustrated in FIG. 4, the position of the obstacle O can be estimated more accurately than in the second example described above, particularly by using the two narrow band search radio waves 310C and 310D.

[0036] 1.2) Obstacle Search An example of the obstacle search procedure of the satellite shown in the above third example will be described below with reference to FIG.

[0037] In Fig. 5, the search control unit 305 notifies other satellites of the start of a search (operation 401). The notification to other satellites may be performed by inter-satellite communication or via a ground station. Next, the search control unit 305 irradiates wide-area search radio waves 310B from the wide-area search antenna 301B in transmission mode (operation 402), and immediately switches to reception mode. The search control unit 305 also sets the communication antenna 301A and the narrow-area search antennas 301C and 301D to reception mode.

[0038] When the reflected waves R31 to R34 of the wide-area search radio wave 310B are received by the wide-area search antenna 301B or all the transmitting and receiving antennas, the search control unit 305 judges whether the reflected wave strength exceeds the threshold value TH (operation 403). The threshold value TH is set to a level at which the reflected wave strength can be judged to be a wave reflected from an obstacle. In other words, if the reception level of the reflected wave is greater than the threshold value TH, it can be judged that an obstacle O large enough to cause an obstacle is present in the space between the satellite S3 and the ground.

[0039] If the reflected wave strength exceeds the threshold value TH (YES in operation 403), the search control unit 305 detects the approximate direction of the obstacle O, for example, depending on which direction of which antenna shows a greater reflected wave strength (operation 404). Next, the search control unit 305 radiates narrow-area search radio waves 310C and 310D from the narrow-area search antennas 301C and 301D, respectively, in the detected approximate direction (operation 405). As already mentioned, when the narrow-area search radio waves 310C and 310D are radiated simultaneously, it is necessary to identify these narrow-area search radio waves by the frequency used or the identification code. It is also possible to radiate the narrow-area search radio waves 310C and 310D sequentially without overlapping.

[0040] The reflected waves R31 to R34 of the narrow area search radio waves 310C and 310D are received by the communication antenna 301A, the wide area search antenna 301B, and the narrow area search antennas 301C and 301D, respectively. The search control unit 305 generates reflected wave information including the reception strength and reception direction of the reflected waves R31 to R34, and outputs the information to the obstacle position estimation unit 306.

[0041] The obstacle position estimation unit 306 estimates the position of an obstacle O existing between the satellite S3 and the earth's surface from the reception strength and reception direction of the reflected wave received by each transmitting and receiving antenna (operation 406). The position information of the obstacle O indicates, for example, in which direction and how far it is from the satellite S3. The relative speed of the obstacle O with respect to the satellite S3 may be calculated from the change in position over time and included in the position information. The obstacle position estimation unit 306 outputs the position information of the obstacle O and the strength of the reflected wave to the countermeasure selection unit 307.

[0042] 1.3) Measures to avoid obstacles The countermeasure selection unit 307 executes a fault recovery countermeasure prepared in advance for communication with the ground station by the communication antenna 301A according to the position information of the obstacle O and the strength of the reflected wave (operation 407). Examples of fault recovery countermeasures are listed below.

[0043] <Soft handover> In a satellite S(f) where an obstacle O is detected and there is a possibility of a communication failure, the countermeasure selection unit 307 refers to the position information of the obstacle O and hands over communication with the ground station B to an adjacent satellite S(n) that is not affected by the obstacle.

[0044] Referring to FIG. 6, it is assumed that an obstacle O1 exists between the satellite S(f) and the ground station and its position is identified by the obstacle search described above. In this case, the satellite S(f) instructs the adjacent satellite S(n) to transmit the same data to the ground station B directly or via the ground station. As a result, the ground station B receives transmission waves 501 and 502 from both the satellites S(f) and S(n). Next, while maintaining communication with the ground station B, the transmission band of the satellite S(f) affected by the obstacle is reduced, and the transmission band of the satellite S(n) not affected by the obstacle is increased. In this way, a handover from the satellite S(f) to the satellite S(n) is executed. In this way, the communication bands of multiple satellites are controlled in a timely manner according to the reflected wave information from the obstacle O1, thereby ensuring the overall communication quality.

[0045] <Selective suppression of transmit beam intensity> In Fig. 6, if the obstacle O1 is a radio wave reflective / scattering object, the beam irradiated to the obstacle O1 will be reflected or scattered by the obstacle O1, which may cause radio wave interference with other satellites or ground stations. Therefore, radio wave interference can be suppressed by forming a null point in the transmission beam 501 from the satellite S(f) and reducing the beam intensity in the direction corresponding to the position of the obstacle O1.

[0046] <Changing the direction of the transmitted beam> A route that bypasses the obstacle O1 is formed by changing the direction of the transmission beam of the communication antenna 301A and passing through another satellite or another ground station.

[0047] <Change of frequency or frequency band> The satellite S(f) changes its carrier frequency to a lower frequency band that can get around obstacles. This can improve communication quality. It is also possible to improve the signal-to-noise ratio (SNR) by narrowing the frequency band.

[0048] <Changing the beam diameter> When the communication antenna 301A of the satellite S(f) is a phased array antenna, the transmission beam diameter can be controlled by increasing or decreasing the number of antenna elements used, which may improve communication quality.

[0049] <Increasing transmit beam strength> If the obstacle O1 is an object such as a cloud that attenuates radio waves while they pass through, the output of the transmission beam in the direction of the obstacle O1 is increased to the extent that the obstacle is eliminated. This is the simplest and most effective way to deal with the problem, since it only involves increasing the transmission output level.

[0050] 1.4) Effects As described above, according to the embodiment of the present disclosure, a search radio wave is transmitted into the space between the satellite and the ground station, and the position of the obstacle is estimated based on the information of the reflected wave. By using the information of the reflected wave of the search radio wave, the position of the obstacle existing between the satellite and the ground station can be estimated in real time.

[0051] Furthermore, according to the embodiment of the present disclosure, search radio waves can be emitted from multiple antennas, and the position of an obstacle can be estimated from the information of the respective reflected waves, making it possible to obtain a more accurate obstacle position.

[0052] 2. Second embodiment In the first embodiment described above, the satellite or ground station radiates a search radio wave and receives the reflected wave to perform an obstacle search, but the present invention is not limited to this. An obstacle search can also be performed by having multiple satellites orbit, one satellite radiates a search radio wave, and an adjacent satellite receives part of the reflected wave from an obstacle.

[0053] 2.1) System configuration As shown in FIG. 7, a number of satellites S1, S2, ... are orbiting the Earth E in a non-geostationary orbit. i In addition to the communication antenna for communicating with the ground station B, the satellite S has the above-mentioned search antenna and an inter-satellite communication antenna for communicating with adjacent satellites. i As shown in any one of the first to third examples described above, it is assumed that the search radio wave can be irradiated toward the ground surface and the reflected wave of the search radio wave can be received.

[0054] As shown in FIG. i has a transmitting / receiving antenna 601 and a wireless communication unit 602. The transmitting / receiving antenna 601 may be composed of a plurality of antennas as shown in the first to third examples described above. The directivity of the transmitting / receiving antenna 601 is changeable, and furthermore, a null point is formed in a desired direction within the beam, and the beam diameter can be controlled by increasing or decreasing the number of antenna elements used. The wireless communication unit 602 is capable of communicating with a ground station, transmitting search radio waves, and receiving reflected waves through the transmitting / receiving antenna 601.

[0055] Furthermore, satellite S ihas a processor unit 603 and a program memory 604. The processor unit 603 is a processing unit that controls the operation of this embodiment, and executes a program stored in the program memory 604 to realize the functions of a search control unit 605, an obstacle position estimation unit 606, a measure selection unit 607, and a control unit 608. The basic functions of the search control unit 605 and the functions of the obstacle position estimation unit 606 and the measure selection unit 607 are the same as those of the first embodiment described above, so a description thereof will be omitted.

[0056] In addition, satellite S i Satellite S flying next to i-1 and S i+1 Satellite S i Since the configuration is the same as that of the satellite S, the illustration is omitted. i , Satellite S i-1 and S i+1 is equipped with an inter-satellite communication function, but this is omitted in Figure 8.

[0057] 2.2) Obstacle Search As shown in FIG. i When the satellite S starts a search, the search control unit 605 i-1 and S i+1 to start a search (operation 701).

[0058] Satellite S i-1 and S i+1 When the satellite S receives the search start notification, it sets the wireless communication unit 602 of the satellite S to a reflected wave reception mode to receive the reflected wave of the search radio wave (operations 702 and 703). i The search control unit 605 emits search radio waves 610 at the notified frequency and timing (operation 704).

[0059] If an obstacle O is present within the irradiation range, the irradiated search radio wave 610 is reflected by the obstacle O. Among these reflected waves, reflected waves R6(i) are reflected by the satellite S. i The reflected wave R6(i-1) is received by the satellite S i-1 The reflected wave R6(i+1) is detected by the satellite S i+1and (operations 706 and 707), respectively.

[0060] Satellite S i-1 and S i+1 Each satellite receives the reflected waves at its own transmitting and receiving antenna. i-1 and S i+1 The search control unit 605 of each satellite generates reflected wave information including the reception direction, reception strength, and reception time of each received reflected wave, and transmits each reflected wave information to the satellite S via inter-satellite communication. i (operations 708, 709).

[0061] Satellite S i The obstacle position estimation unit 606 of the satellite S i Reflected wave information from satellite S i-1 and S i+1 The position of the obstacle O is estimated from the reflected wave information received from the satellites S and S (operation 710). i , Satellite S i-1 and S i+1 By using each of the antennas as a reflected wave receiving antenna, it is possible to estimate the obstacle position using multiple transmitting and receiving antennas, as already described.

[0062] Satellite S i When the countermeasure selection unit 607 receives the estimated position information of the obstacle O, it can execute the above-mentioned fault recovery countermeasure (operation 711).

[0063] 2.3) Effects As described above, according to the second embodiment of the present disclosure, the position of an obstacle between a satellite and a ground station can be estimated in real time by using multiple satellites in cooperation with each other. In particular, by emitting a search wave from the antenna of one satellite and detecting the reflected wave by multiple satellites, the position of the obstacle can be estimated more accurately from the reflected wave information.

[0064] 3. Third embodiment In the above-mentioned first and second embodiments, an example is described in which a satellite irradiates a search radio wave and performs obstacle position estimation and obstacle countermeasures from the reflected wave. However, a satellite generally has a limit on its power consumption. Therefore, instead of the satellite performing obstacle position estimation and obstacle countermeasures, which have a large processing load, the ground station B may perform similar processing. Hereinafter, a description will be given with reference to FIG. 10, but since the functions of search control, obstacle position estimation, and obstacle countermeasures are the same as those in the above-mentioned first embodiment, the same reference numbers are used and the description will be omitted.

[0065] As shown in Fig. 10, the ground station B has a transmitting / receiving antenna 801 and a wireless communication unit 802. The transmitting / receiving antenna 801 may be provided as a separate transmitting antenna and a receiving antenna, or may serve as both a transmitting antenna and a receiving antenna. In this embodiment, the transmitting / receiving antenna 801 can control the directionality by using a phased array antenna. Search radio waves 810 having multiple irradiation ranges can be irradiated by using multiple phased array antennas.

[0066] When the transmitting / receiving antenna 801 serves as both a transmitting antenna and a receiving antenna, the transmitting mode and the receiving mode can be switched by the wireless communication unit 802. The directivity of the transmitting / receiving antenna 801 can be changed, and furthermore, a null point can be formed in a desired direction within the beam, and the beam diameter can be controlled by increasing or decreasing the number of antenna elements used.

[0067] The wireless communication unit 802 is capable of communicating with satellite S, transmitting search radio waves, and receiving reflected waves through the transmitting / receiving antenna 801. Note that the transmitting / receiving antenna 801 may be provided with a separate antenna for communicating with satellite S, a separate antenna for transmitting search radio waves, and a separate antenna for receiving reflected waves. By providing one or more dedicated search antennas separate from the communication antennas, the position of an obstacle can be estimated more accurately.

[0068] Furthermore, ground station B has a processor unit 803 and a program memory 804, and the processor unit 803 is a processing unit that controls the operation of this embodiment. The processor unit 803 is composed of one or more processors. The processor unit 803 executes a program stored in the program memory 804 to realize the functions of a search control unit 105, an obstacle position estimation unit 106, a countermeasure selection unit 107, and a control unit 108. Each function of the processor unit 803 is as described in the first and second embodiments above, so description thereof will be omitted.

[0069] As described above, according to the embodiment of the present disclosure, the ground station B transmits the search radio wave 810 instead of the satellite with limited power consumption, and estimates the position of the obstacle based on the information of the reflected wave. By using the reflected wave information of the search radio wave, the position of the obstacle existing between the satellite and the ground station can be estimated in real time. Also, as in the first and second embodiments described above, the search radio wave can be emitted from multiple antennas, and the position of the obstacle can be estimated from the information of each reflected wave, making it possible to obtain a more accurate obstacle position.

[0070] It should be noted that both the satellite S and the ground station B may implement the above-mentioned functions of search control, obstacle position estimation, and countermeasure selection.

[0071] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-mentioned embodiments. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be appropriately combined with other embodiments.

[0072] 4. Notes A part or all of the above-described embodiment and examples may be described as follows, but is not limited to these. (Appendix 1) 1. An apparatus for searching for an obstacle between at least one satellite orbiting in a satellite communication system and a ground station, the apparatus comprising: At least one of the satellite and the ground station, a wireless communication unit that transmits a search radio wave and receives a reflected wave of the search radio wave; a processing unit that controls the wireless communication unit and estimates a position of the obstacle based on information about the reflected wave; An obstacle search device including: (Appendix 2) 2. The obstacle search device according to claim 1, wherein the wireless communication unit is connected to a plurality of transmitting / receiving antennas, each transmitting / receiving antenna transmitting its own search radio wave and receiving a reflected wave of the search radio wave. (Appendix 3) the plurality of transmitting / receiving antennas include a first transmitting / receiving antenna and a second transmitting / receiving antenna that are spaced a predetermined distance apart; 3. The obstacle search device according to claim 2, wherein the processing unit estimates the position of the obstacle based on a first reflected wave received by the first transmitting / receiving antenna and a second reflected wave received by the second transmitting / receiving antenna. (Appendix 4) 2. The obstacle search device according to claim 1, wherein the processing unit controls an irradiation range of the search radio wave. (Appendix 5) 5. The obstacle search device according to claim 4, wherein the wireless communication unit is connected to a plurality of transmitting and receiving antennas, the plurality of transmitting and receiving antennas including a wide area search antenna and a narrow area search antenna having relatively different irradiation ranges. (Appendix 6) 6. The obstacle search device according to claim 4 or 5, wherein the processing unit estimates the position of the obstacle with higher accuracy by emitting the search radio waves over a wide area and then emitting a narrow-area search radio wave in a direction estimated based on the reflected wave. (Appendix 7) A satellite equipped with an obstacle search device according to any one of claims 1 to 6. (Appendix 8) The satellite described in claim 7, wherein the processing unit notifies other satellites of the frequency and transmission timing of the search radio waves via inter-satellite communication or satellite-to-ground station communication, and estimates the position of the obstacle based on information on the reflected waves received by the wireless communication unit and information on the reflected waves received by the other satellites. (Appendix 9) A method for searching for an obstacle between at least one orbiting satellite and a ground in a satellite communication system including a plurality of ground stations, the method comprising: The wireless communication unit transmits a search radio wave and receives a reflected wave of the search radio wave; a processing unit controls the wireless communication unit to estimate a position of the obstacle based on information of the reflected wave; Obstacle search method. (Appendix 10) 10. The obstacle search method according to claim 9, wherein the wireless communication unit is connected to a plurality of transmitting / receiving antennas, each transmitting / receiving antenna transmitting its own search radio wave and receiving a reflected wave of the search radio wave. (Appendix 11) the plurality of transmitting / receiving antennas include a first transmitting / receiving antenna and a second transmitting / receiving antenna that are spaced a predetermined distance apart; 11. The obstacle search method according to claim 10, wherein the processing unit estimates the position of the obstacle based on a first reflected wave received by the first transmitting / receiving antenna and a second reflected wave received by the second transmitting / receiving antenna. (Appendix 12) 10. The obstacle searching method according to claim 9, wherein the processing unit controls an irradiation range of the search radio wave. (Appendix 13) The obstacle search method according to claim 12, wherein the wireless communication unit is connected to a plurality of transmitting / receiving antennas, the plurality of transmitting / receiving antennas include a wide area search antenna and a narrow area search antenna having relatively different irradiation ranges, and the processing unit selects the wide area search antenna and the narrow area search antenna. (Appendix 14) 14. The obstacle search method according to claim 12 or 13, wherein the processing unit estimates the position of the obstacle with higher accuracy by irradiating the search radio wave over a wide area and then irradiating a narrow-area search radio wave in a direction estimated based on the reflected wave. (Appendix 15) A satellite communications system comprising at least one orbiting satellite and a plurality of ground stations, The satellite, a wireless communication unit that transmits a search radio wave and receives a reflected wave of the search radio wave; a processing unit that controls the wireless communication unit and estimates a position of the obstacle based on information of the reflected wave; A satellite communication system comprising: (Appendix 16) 16. The satellite communication system according to claim 15, wherein the processing unit notifies other satellites of the frequency and transmission timing of the search radio waves via inter-satellite communication or satellite-to-ground station communication, and estimates the position of the obstacle based on information on the reflected waves received by the wireless communication unit and information on the reflected waves received by the other satellites. (Appendix 17) 17. The satellite communication system according to claim 15, wherein the wireless communication unit is connected to a plurality of transmitting / receiving antennas, each transmitting / receiving antenna transmitting its own search radio wave and receiving a reflected wave of the search radio wave. (Appendix 18) the plurality of transmitting / receiving antennas include a first transmitting / receiving antenna and a second transmitting / receiving antenna that are spaced a predetermined distance apart; 18. The satellite communication system according to claim 17, wherein the processing unit estimates the position of the obstacle based on a first reflected wave received by the first transmitting / receiving antenna and a second reflected wave received by the second transmitting / receiving antenna. (Appendix 19) 17. The satellite communication system according to claim 15, wherein the processing unit controls an irradiation range of the search radio wave. (Appendix 20) 20. The satellite communication system according to claim 19, wherein the wireless communication unit is connected to a plurality of transmitting and receiving antennas, the plurality of transmitting and receiving antennas including a wide area search antenna and a narrow area search antenna having relatively different irradiation ranges. (Appendix 21) The satellite communication system of claim 19, wherein the processing unit estimates the position of the obstacle with higher accuracy by emitting the search radio waves over a wide area and then emitting a narrow-area search radio wave in a direction estimated based on the reflected wave. (Appendix 22) A program for causing a computer to function as a device for searching for an obstacle between at least one satellite orbiting in a satellite communication system including at least one satellite and a plurality of ground stations, the program comprising: A function of a wireless communication unit of at least one of the satellite and the ground station transmitting a search radio wave and receiving a reflected wave of the search radio wave; a function of a processing unit controlling the wireless communication unit and estimating the position of the obstacle based on information of the reflected wave; A program for realizing the above on the computer. [Industrial Applicability]

[0073] The present invention is applicable to a satellite communication system that performs wireless communication between an orbiting satellite and a ground station. [Explanation of symbols]

[0074] 101 Transmitting and receiving antenna 102 Wireless Communication Department 103 Processor section 104 Program Memory 105 Search control section 106 Obstacle position estimation unit 107 Countermeasure Selection Division 110 Search Radio Waves O Obstacles R10 reflected wave

Claims

1. 1. An apparatus for searching for an obstacle between at least one satellite orbiting in a satellite communication system including a plurality of ground stations and the satellite, the apparatus comprising: At least one of the satellite and the ground station, a wireless communication unit that transmits a search radio wave and receives a reflected wave of the search radio wave; a processing unit that controls the wireless communication unit and estimates a position of the obstacle based on information about the reflected wave; An obstacle search device including:

2. 2. The obstacle search device according to claim 1, wherein the wireless communication unit is connected to a plurality of transmitting / receiving antennas, each transmitting / receiving antenna transmitting its own search radio wave and receiving a reflected wave of the search radio wave.

3. the plurality of transmitting / receiving antennas include a first transmitting / receiving antenna and a second transmitting / receiving antenna that are spaced a predetermined distance apart, 3. The obstacle search device according to claim 2, wherein the processing unit estimates the position of the obstacle based on a first reflected wave received by the first transmitting / receiving antenna and a second reflected wave received by the second transmitting / receiving antenna.

4. 2. The obstacle search device according to claim 1, wherein the processing unit controls an irradiation range of the search radio wave.

5. 5. The obstacle search device according to claim 4, wherein the wireless communication unit is connected to a plurality of transmitting and receiving antennas, the plurality of transmitting and receiving antennas including a wide area search antenna and a narrow area search antenna having relatively different irradiation ranges.

6. 6. The obstacle search device according to claim 4 or 5, wherein the processing unit estimates the position of the obstacle with higher accuracy by irradiating the search radio wave over a wide area and then irradiating a narrow-area search radio wave in a direction estimated based on the reflected wave.

7. A satellite equipped with an obstacle search device according to any one of claims 1 to 5.

8. The satellite described in claim 7, wherein the processing unit notifies other satellites of the frequency and transmission timing of the search radio waves via inter-satellite communication or satellite-to-ground station communication, and estimates the position of the obstacle based on information on the reflected waves received by the wireless communication unit and information on the reflected waves received by the other satellites.

9. 1. A method for searching for an obstacle between at least one orbiting satellite and a ground in a satellite communication system including a plurality of ground stations, the method comprising: The wireless communication unit transmits a search radio wave and receives a reflected wave of the search radio wave; a processing unit controls the wireless communication unit to estimate a position of the obstacle based on information of the reflected wave; Obstacle search method.

10. A satellite communications system comprising at least one orbiting satellite and a plurality of ground stations, The satellite, a wireless communication unit that transmits a search radio wave and receives a reflected wave of the search radio wave; a processing unit that controls the wireless communication unit and estimates a position of the obstacle based on information of the reflected wave; A satellite communication system comprising:

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