JPH08181643A - Communication enable time notice system for satellite communication - Google Patents

Abstract

PURPOSE: To provide information such as a satellite communication enable time, a time zone and an available time rate by grasping a passing time of a non-geostationary satellite from which a satellite signal is received in advance so as to detect the communication available time zone information. CONSTITUTION: A visual satellite detection circuit 90 uses visible space area information 94 outputted from a visible space area detection circuit 92 and elevating angle, azimuth and time information 89 outputted from a satellite elevating angle/azimuth arithmetic circuit 88 to detect an azimuth, elevating angle and time in a tangential direction to a satellite orbit seen from a communication terminal equipment and to provide an output of contact point information 97. Based on the information 97 and an absolute time 87 being an output of a clock 79, communication enable time information 101 is obtained by a satellite visible time detection circuit 98, a satellite visible time length detection circuit 99 detects visual time length information 102 and an azimuth dependent time rate arithmetic circuit 100 obtains communication enable time rate information 103, and the sets of the information are displayed on a communication enable time display device 104, a communication enable time zone display device 105, a communication enable time display device 106 and an azimuth dependent time rate display device 107 for the notice of the operator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite communication system such as a fixed satellite communication system, a mobile satellite communication system and a personal satellite communication system for performing satellite communication using non-geostationary satellites, and particularly to satellite communication. The present invention relates to the available time notification method.

[0002]

2. Description of the Related Art In recent years, in the United States and European countries, proposals for commercial services using non-geostationary satellites orbiting non-geostationary orbits are mainly aimed at mobile satellite communication services.
Many studies have been made.

In the United States, Motorola aims at commercialization from 1998, and has a total of 6 in a low altitude orbit (LEO) with a satellite altitude of about 780 km.
We are proposing the Iridium Project, which will deploy six orbiting satellites to realize a worldwide personal satellite communication system. In addition, a total of 4 in low altitude orbits with an altitude of 1,289 km
A global star from Qualcom, a mobile satellite communication system that has eight satellites and continuously covers the entire world, and a medium orbit (ME) with an altitude of 10,370 km.
1 for O: Medium Earth Orbit)
TRW's Odyssey system, etc. has been proposed in the United States for the purpose of constructing a global network covering two major regions of the world by allocating two satellites, and the movement towards the realization of these systems has been activated. It's starting.

On the other hand, European countries are also interested in mobile satellite communication systems using these non-geostationary satellites, and particularly in ESA (European Space Agency), a long elliptical orbit (HEO: Highly Ell) suitable for a high latitude area.
ARCHIM using optical Orbit)
We are proposing and considering an EDES plan. Furthermore, in INMARSAT which is an international mobile satellite communication system,
Satellite altitude 1 aiming to start service after 000 years
10 satellites are placed in the middle altitude orbit of 0,355km,
BACKGROUND ART IN MARSAT-P systems for the purpose of providing personal satellite communication services using mobile terminals to the whole world are being actively studied and developed.

By the way, the above-mentioned mobile satellite communication system using non-geostationary satellites has the following characteristics, unlike the conventional satellite communication system using a geostationary orbit. (1) The arrangement of satellites visible to users on the ground changes with the passage of time. (2) Since the position of the non-geostationary satellite used by the user at the start of communication may be out of the range of the visible elevation angle over time, it may be necessary to switch the non-geostational satellite for communication. (3) Depending on the location (latitude / longitude) of the user,
Since the satellite elevation angle and satellite orientation of the non-geostationary satellites that can be observed by the user are different, there is a possibility that the spatial region in which the non-geostationary satellites can be observed is limited only to a specific satellite elevation angle and a specific satellite orientation. (4) The time rate at which the user can communicate, the time of day, the length of time during which continuous communication is possible, and the like differ depending on the environment around the place where the user exists. For example, when a user communicates in a state where a building or an elevated building is standing upright in a city, even if the satellite signal from the non-geostationary satellite is blocked by the building at a certain time, the time elapses. At the same time, the satellite constellation changes, so there are time zones when communication is possible. On the contrary, even if communication is possible at a certain time, the satellite signal is cut off over time,
There are also cases where communication is lost. In the case of a mobile satellite communication system using a geostationary satellite, it is fixedly divided into an area where communication is possible and an area where communication is not possible, depending on the position of the user.

With regard to the above (2), in the land earth station which establishes a line connection between the mobile earth station and the ground communication network, the reception level of the satellite signal transmitted from the user is constantly monitored and the reception level is regulated. If it falls below the range, the method of switching the channel to another non-geostationary satellite that can be received, or the mobile earth station constantly monitors the reception level of the satellite signal transmitted from the land earth station, and the reception level falls below the specified threshold. Various methods have been considered, including a method of requesting the land earth station to switch the channel to another non-geostationary satellite that can be received. The satellite signal blocking described in (4) above is a factor that significantly deteriorates the satellite channel quality, and various studies and proposals are currently being made to address this problem, but both are directly resolved. Not a measure
The best method has not been established.

[0007]

When the earth station of the satellite communication system using non-geostationary satellites as described above, that is, the communication terminal is used in a room such as a hotel or a building, the blocking of the satellite signal by the building is prevented. Impact is a problem. That is, the field of view is narrowed (less than half) as compared with the case of using the terminal outdoors, so that the time period during which communication is possible is limited. On the other hand, for a user who communicates from inside the room, (1) whether communication is possible at the present time (2) if communication is not possible, the time must wait until communication is possible (3) communication is possible In this case, information about communication time, such as the length of time that continuous communication is possible, is extremely important and is a factor that greatly affects the user's action schedule. For example, the following are assumed as the communication requesting degree of the user existing in the room. (A) Urgent voice call and data communication (immediateness is required, and the demand for communication is highest) (b) Normal voice call and data communication (immediateness is not required, but within a limited time) Communication must be performed, for example, regular business contact, file transfer, exchange of business emails, etc.) (c) Low demand for voice calls, data communications, and communications with low importance , Communication that depends on the judgment of the user (for example, contacting family and friends, exchanging private e-mail, etc.)

Here, it is assumed that the user confirms that communication is impossible, for example, when the user confirms the communication terminal placed near the window in the room. At this time, the information regarding “the time when communication is possible and the time period when communication is possible” is extremely important. That is, even if communication is not possible at the present time, if it is known in advance that communication will be possible, for example, in one hour, efficient schedule management can be performed and the user can feel secure. it can. On the contrary, if you know in advance that communication is impossible for several hours, without wasting time,
Users can take action based on their own judgment. On the other hand, when the user confirms the communication terminal placed near the window in the room and it is found that the communication is possible, the information about "the length of time for continuous communication from the current time" becomes extremely important. . That is, even if communication is possible at the present time, continuous communication must be possible for a relatively long period of time, for example, when performing FAX transmission or data file transfer. Therefore, if the length of time for which continuous communication is possible is known in advance from the current time, data transmission can be completed without causing communication interruption. Here, the above operation example assumes that the user uses the communication terminal in the room of a building such as a building, but the problem that the communication time is limited due to the influence of blocking of satellite signals is operated indoors. The present invention is not limited to this case, but it is also a serious problem when satellite communication is performed outdoors, such as in hilly areas, mountainous areas, valleys, and forest areas where the field of view is restricted. That is, in a place where the field of view is limited by mountains or trees, information about communication time is extremely important, as in the case of performing satellite communication from the room.

[0009]

However, in the satellite communication systems using non-geostationary satellites that have been proposed in the past, no method for providing information on the communication time as described above has been proposed, and communication is possible. The continuity and continuity are not guaranteed. Therefore, while holding the communication terminal, the user does not know when the communication can be performed, and even if the communication is possible, the line is suddenly cut off during the communication and the communication cannot be made without completing the communication. Many obstacles such as loss can occur.

Further, the satellite communication system in which the non-geostationary satellites are arranged on the orbital plane inclined with respect to the equator is characterized in that the satellites do not arrive in a particular direction depending on the position of the user on the earth. Therefore, when the communication terminal is operated indoors, there is a possibility that a communicable time rate greatly varies depending on the position of the window where the communication terminal is installed. However, no specific method has been proposed so far to deal with this problem. Therefore, for example, when the windows of the hotel room have two directions of true north and true east, there is a situation in which communication cannot be performed at all depending on whether the terminal is placed in the true north window or true east. There are two extreme cases of situations where communication is possible. Further, when the visible space exists only in the direction in which satellites do not arrive, communication becomes impossible, but there is a problem that the user cannot know this in advance.

It is an object of the present invention to provide a satellite communication available time notification system capable of knowing information about the available communication time before the start of communication and during communication.

[0012]

To achieve this end, the present invention employs the novel featured methods summarized below.

That is, a visible space region in which a transmission signal transmitted from a non-geostationary satellite is receivable at an earth station operated by a user, that is, a skyline from the earth station is detected by the earth station, and information on the visible space region is detected, And the elevation angle of the non-geostationary satellite observable from the earth station, which is derived using the position information of the earth station and the orbit information of the non-geostationary satellite,
Using satellite information such as azimuth angle, grasp the transit time of non-geostationary satellites that satellite signals can be received at the earth station in advance,
Various information such as the time, time zone, and available time rate that satellite communication is possible for the user by detecting information on the time zone during which communication between the earth station and non-geostationary satellites is possible. Can be provided.

Further, as a method for the earth station to detect a space visible area in which a transmission signal from a non-geostationary satellite can be received by the earth station, an aerial part observable from the earth station and ground structures, trees, hilly areas, etc. The boundary line with the shielded object, that is, the skyline from the earth station is detected using a device that can recognize the shadow of the object existing in the spatial area such as a photoelectric element or an infrared device, and information about the skyline and the earth are detected. Using the satellite information such as elevation and azimuth of the non-geostationary satellite that can be observed from the earth station, which is derived using the position information of the station and the orbit information of the non-geostationary satellite, the non-satellite signal that the earth station can receive By grasping the transit time of the geostationary satellite in advance, it is possible to detect the information on the time zone during which the communication between the earth station and the non-geostation satellite is possible.

Further, as a method for the earth station to detect a time zone during which a signal transmitted from a non-geostationary satellite can be received by the earth station, a history of whether satellite signals are received or not is recorded in the earth station, and a certain non-specific When the transmission signal from the geostationary satellite is receivable, the satellite elevation angle and the satellite azimuth from the earth station to the non-geostation satellite at the time of reception of the satellite signal are calculated using the position information of the earth station and the orbit information of the non-geostation satellite. Detecting and recognizing that the transmission signals of all non-geostationary satellites with the same satellite azimuth as the non-geostationary satellite and elevation angles higher than that of the non-geostationary satellite can be received by the earth station, at the same time When the satellite detects the time when the satellite arrives in the satellite direction of the non-geostationary satellite as the communication available time, on the other hand, when the transmission signal from another specific non-geostationary satellite cannot be received, The satellite elevation angle and the satellite bearing from the earth station to the particular non-geostationary satellite are detected at the earth station, and the satellite orientation is the same as the particular non-geostationary satellite and the satellite elevation angle is lower than the particular non-geostationary satellite. At the same time recognizing that the non-geostationary satellite transmission signal is unreceivable at the earth station, at the same time detecting the time when the corresponding non-geostationary satellite arrives in the satellite direction of the above-mentioned specific non-geostationary satellite, as the uncommunication time It is possible to grasp the passing time of a non-geostationary satellite that can receive satellite signals at the earth station with the passage of time, and detect information regarding the time zone during which communication between the earth station and the non-geostationary satellite is possible.

Further, the visible space region is obtained by using the position information of the earth station and the satellite information such as the elevation angle and the azimuth angle of the non-geostation satellite observable from the earth station, which is derived using the orbit information of the non-geostation satellite. When the earth station is installed only in a certain direction, the communication time ratio in each direction from the earth station installation position is derived to achieve the highest communication time ratio for the user. It is possible to notify in advance the possible directions, or to notify in advance the communicable time rate for all directions.

Further, the communicable time ratio in the earth station, which is derived with the passage of time based on the reception result of the transmission signal from the non-geostationary satellite, is the communicable time ratio within a preset arbitrary unit time. Below the minimum value of
Warnings can be issued to users of the earth station.

[0018]

[Effect] When the user who is the operator of the earth station tries to communicate, communication is impossible at the time, that is, even when the satellite does not exist in the visible space, the time when communication is possible and the communication is performed in advance. The user can manage the schedule efficiently because the available time zone is known. On the contrary, since it is known in advance that communication cannot be performed for several hours, the user can decide the action schedule based on his / her own judgment without wasting time. On the other hand, when the user who is the operator of the earth station can communicate at the time of attempting communication, that is, when the satellite exists in the visible space area, the time length for continuous communication from the current time is known in advance, The desired communication can be completed without causing communication interruption.

Even if the visible space region of the user who operates the earth station is limited only to the installation direction of the communication terminal, the azimuth with the highest communicable time rate can be detected in advance. On the other hand, it is possible to guarantee communication with a high probability. Furthermore, even if the visible space area of the user is limited to a specific direction, the time and length of time when communication is possible in each direction can be known in advance, so communication can be performed with the shortest waiting time. .

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a usage pattern of a satellite communication system to which the method of the present invention can be applied. 1 and 2 are non-geostationary satellites whose positions move with the passage of time, 3, 4 and 5 are buildings, Reference numeral 6 denotes a window arranged in a room of the building where the user is present, and 7 denotes a communication terminal of the satellite communication system. Here, the field of view that can be seen from the communication terminal 7 is limited to the azimuth within about 180 degrees seen from the window 6, and the visible space region is set to a specific elevation angle and azimuth due to the group of buildings 3 to 5 standing in front of each other. Only limited. Although the figure shows the satellite constellation at a certain time, at this time, the transmission signal from the non-geostationary satellite 1 is blocked by the building 3 and the communication terminal 7 cannot receive the satellite signal 8. On the other hand, non-geostationary satellite 2
The transmission signal from is not blocked by a building or the like, the communication terminal 7 can receive the satellite signal 9, and communication can be performed with the non-geostation satellite 2.

FIG. 2 shows a field of view that can be seen through the window 6 from the interior of the building where the user is present. The field of view of the communication terminal 7 is limited to approximately 180 degrees in the direction in which the window 6 is present. There is. Further, it is apparent from the drawing that the visible space region viewed from the communication terminal 7 is limited to a specific azimuth direction and an elevation angle direction by the building groups 3 to 5 located in the front direction of the window 6. Here, by installing the external element 10 for visible space area recognition in the direction of the window 6, the presence or absence of an object existing in a visual field of about 180 degrees can be taken into the visible space area recognition device 11 as image information. Here, as the external device 10 for recognizing the visible space region, various devices such as a general-purpose CCD camera, an infrared device, and a radiometer are conceivable. Based on the image information obtained from these external devices 10, the visible space region is recognized. That is, the skyline from the communication terminal 7 can be easily detected by the visible space area recognition device 11. Here, the detection result of the skyline from the communication terminal 7 in the communication form of FIG. 2 is shown in FIG.

FIG. 3 shows the field of view seen from the communication terminal 7 in polar coordinates in the communication form of FIG. 1, in which the angular component of the coordinate system represents the azimuth and the contour lines of the coordinate system represent the elevation angle. The elevation angle of the visual field from the communication terminal 7 approaches 90 degrees as it approaches the center. Further, it is assumed that the window 6 is arranged in the north direction in the room where the user is present, and the communication terminal 7 is arranged near the window 6. In this case, the view from the communication terminal 7 is open in the north direction, but the view is limited to a specific spatial region by the buildings 3, 4, and 5 in FIG. In FIG. 3, a shaded portion indicates a region where the visual field of the communication terminal 7 is blocked by the influence of a building or the like. Especially 12, 13, 14
The shaded portions shown by represent the spatial regions blocked by the buildings 3, 4, and 5, respectively.
Therefore, the boundary between the shaded portion and the blank portion is the communication terminal 7
Represents the skyline from, and the blank area is the visible space area.

Next, FIG. 4 shows an example of satellite orbits of a satellite communication system using non-geostationary satellites. The orbits of a plurality of non-geostationary satellites that can be observed from the location around the communication terminal 7 are shown. The loci 20 to 34 are represented by an azimuth and an elevation angle from the communication terminal 7. The coordinate system is the same coordinate system as in FIG. 3, and represents a satellite orbit that can be observed when the visual field of the communication terminal 7 is completely open in the entire spatial region of 360 degrees (however, the elevation angle is 5 degrees or more). In the example of the orbit in the figure, it can be seen that a large number of non-geostationary satellites with high elevation angles are concentrated in the direction east of the communication terminal 7, and many non-geostational satellites with low elevation angles also fly in the west field of view.

Next, FIG. 5 shows an actual satellite orbit that can be observed from the communication terminal 7 when the satellite orbit of FIG. 4 is applied to the communication form of FIG. Since the user is inside the building, the field of view is completely blocked in the south direction centering on the communication terminal 7, and it is possible to observe only non-geostationary satellites flying in the north direction. However, satellite signals are blocked by buildings 3-5 12-
Satellites flying in the shaded area 14 cannot be observed from the communication terminal 7. Here, the communication terminal 7 uses the position information of itself and the orbit information of the non-geostationary satellite to generate the information shown in FIG.
It is possible to easily calculate the satellite orbits of the non-geostationary satellites shown in, and it is possible to recognize in advance the elevation angles and azimuths of all the non-geostationary satellites, and the exact times located at their coordinates. Therefore, by detecting the contact point between the skyline and the satellite orbit, the corresponding non-geostationary satellite is detected by the communication terminal 7
It is possible to simultaneously derive the exact time when it starts to be visible, the exact time when a non-geostationary satellite disappears due to being hidden by a building or sinking in the horizon, and the observable continuous time length.

The position information of the communication terminal is derived by a positioning function of the terminal itself, or the position of the user is monitored by a land earth station, and the information is notified using a downlink communication line. Although various methods such as a method are conceivable, it is assumed here that the communication terminal 7 obtains its own position information by some means by positioning with the existing technology. Regarding the orbit information of non-geostationary satellites, the method of writing in advance in the storage element of the communication terminal 7 or the orbit information of non-geostationary satellites is broadcast from the land earth station using the control channel, and the terminal receives the orbital information. Although various methods such as a decoding method are conceivable, similarly, in the present invention, it is assumed that the communication terminal 7 obtains the orbit information of the non-geostationary satellite by some means by positioning it with the existing technology. Further, the satellite position information such as the elevation angle and the azimuth of the non-geostationary satellite does not need to be calculated by the communication terminal 7, and a method of separately calculating it by an external device (for example, visible space region recognition device) may be considered.

In FIG. 5, the orbits of the non-geostationary satellites which can be communicated from the communication terminal 7 are about half of 23, 24, 29 and 25.
It is limited to a part of ~ 28,30 and a very small part of 22,31, and these are shown on the time axis in the schedule table of FIG. FIG. 6 shows a time zone in which a user existing in the room can perform satellite communication using the communication terminal 7 on a scale of 24 hours, and a black portion of the schedule table indicates a time zone in which communication is possible. , The white part represents the time zone when communication is impossible. As shown in the figure, the time zone where communication is possible and the time zone where communication is impossible appear alternately,
In the worst case, it can be seen that the state in which communication is impossible continues for almost one hour. However, by using this schedule table, the user who uses the communication terminal of the satellite communication system can determine in advance the time and time zone in which communication is possible, the length of time for continuous communication, the time rate for communication, etc. Since the information can be known, it is possible to set the time efficiently.

Next, as an example of a method for the earth station to detect a time zone in which a signal transmitted from a non-geostationary satellite can be received by the earth station, an embodiment of a method of utilizing the history of the presence or absence of satellite signal reception will be described below. explain. First, the following items are assumed as a premise. (1) The earth station having the communication terminal 7 can recognize which non-geostationary satellite is in an observable state by receiving the satellite signal transmitted from the non-geostationary satellite. (2) The earth station uses some method (for example, recording in advance in a storage element of the earth station or broadcasting orbit information from a non-geostationary satellite, and the earth station receiving and decoding the satellite orbit). Information can always be recognized. (3) The earth station uses some method (for example, the position of the earth station is detected by the land earth station at the time of communication, the information is transferred to the earth station, and the information is recorded in a storage element held by the earth station, or It recognizes its own position by using a manual input method or using an independent positioning system. Even if the earth station does not recognize its own position, a method of estimating the position of the earth station from a combination of the time length and time that the non-geostationary satellite can observe can be adopted. (4) The earth station has an accurate clock. (5) Do not move the communication terminal of the earth station or the antenna part (high frequency part) connected to the communication terminal by wire or wirelessly from the state of being placed near the window (semi-fixed state). It should be noted that when moving in a place where the state of the field of view hardly changes, for example, when moving in a grassland area where mountain ranges are distant, or when traveling in a certain direction on an urban road where almost constant buildings are continuous on both sides of the road. It is possible to apply this method while the user is moving without fixing the communication terminal or the antenna.

At this time, the communication terminal 7
Will be able to communicate with the land earth station at the time, time zone,
And data on the length of time can be detected.
It is to grasp the passing time of a non-geostationary satellite capable of receiving satellite signals at the earth station with the passage of time and detect information on the time zone during which communication between the earth station and the non-geostationary satellite is possible. (1) When a transmission signal from a non-geostationary satellite is receivable, the satellite elevation angle and the satellite azimuth from the earth station to the non-geostationary satellite at the time when the satellite signal is received are used as the position information of the earth station. It is derived using orbit information of non-geostationary satellites. (2) Transmission signals of all non-geostationary satellites, which have the same satellite azimuth as the non-geostationary satellite of (1) and whose satellite elevation angle is higher than that of the non-geostationary satellite, can be received by the earth station. Recognize. However, since the satellite signal with a high elevation angle may be blocked due to the shape of the building, it may be necessary to set an upper limit on the elevation angle in some cases. (3) According to the results of (2), the time at which the corresponding non-geostationary satellite arrives in the direction of the non-geostational satellite of (1) is detected as the communicable time. (4) In the results of (2), it is uncertain whether communication can be reliably performed for non-geostationary satellites that have the same direction as the target non-geostationary satellite but have a lower elevation angle than the non-geostationary satellite. The time zone is recognized as the time when communication is possible. (4) On the other hand, when the transmission signal from the non-geostationary satellite cannot be received, the earth station detects the satellite elevation angle and the satellite azimuth from the earth station to the unobservable non-geostationary satellite at that time. (5) The satellite signals cannot be received. The transmission signals of all the non-geostationary satellites in the same satellite azimuth as the non-geostationary satellite of (4) and the satellite elevation angle is lower than the non-geostationary satellite cannot be received by the earth station. Recognize that there is. (6) According to the results of (5), the time when the corresponding satellite arrives in the azimuth of the non-geostationary satellite of (4) is detected as the communication impossible time. (7) In the results of (4), it is uncertain whether or not the non-geostationary satellite, which has the same direction as the target non-geostationary satellite but has a higher elevation angle than that, cannot reliably communicate. Therefore, the time zone is recognized as a time when communication is unlikely to occur. (8) The uncertain time zone decreases with the passage of time, and the non-geostationary satellite makes a cycle of one cycle, so that it is possible to completely grasp the time zone in which communication is possible and the time zone in which communication is not possible. .

A specific embodiment using the above procedure will be described with reference to FIGS. 7 and 8. FIG. 7 shows this procedure in FIG.
FIG. 4 shows an example of satellite orbit when applied to the communication mode of FIG. 1, in which the transmission signal from the non-geostationary satellite orbiting the satellite orbit 40 is transmitted for a certain time after the user installs the transmission terminal at the window in the figure. It is assumed that the reception was possible for the first time. In this case, all the non-geostationary satellites existing within the range of the azimuth angle 52 in which the satellite orbit 40 was receivable and having a satellite elevation angle higher than the satellite orbit 40 (about 20 degrees or more) are receivable. It recognizes and detects the transit time of the non-geostationary satellites passing the satellite orbits 41 to 44 satisfying this condition as the communicable time zone. Similarly, assuming that the satellite orbit 45 is receivable after a certain period of time, the non-geostationary satellite exists within the range of the azimuth 53 that the non-geostationary satellite was receivable, and the satellite elevation angle is 45. High elevation (about 3
Recognizing satellite orbits 46-51 which range from 0 to 65 degrees or more)
The transit time of non-geostationary satellites orbiting these orbits is detected as the communicable time zone.

FIG. 8 shows an embodiment of a process of creating a communication available time schedule table which is sequentially updated with the lapse of time from the start of reception of satellite signals by the procedure shown in the embodiment of FIG. , The schedule is expressed on a 24-hour scale. Here, the time zones represented by the blocks 65 to 69 are, respectively, "communication time", "communication time", "communication possibility time", and "communication possibility time". It represents "low time" and "time when it is unknown whether communication is possible". In the figure, reference numeral 61 represents the satellite signal reception start time, and at the reception start time 60, no information regarding the available communication time is obtained. Next, reference numeral 62 represents the state of the communicable time schedule table when several tens of minutes have elapsed from the reception start time, and the time length in which it is known whether communication is possible is extremely small. 63 is the state of the schedule table after a few hours have passed, and it is determined whether communication is possible or not in a considerable time period.
The user who operates the earth station can estimate the time and length of time when communication is possible using this schedule table to some extent. Finally, 64 represents the state at the time of completion of the communicable time schedule table obtained when all the non-geostationary satellites orbit the earth for one cycle. By using this schedule table, a user who uses a communication terminal of a satellite communication system can know in advance the time when communication is possible, the time zone, the length of time that continuous communication is possible, the communication time rate, etc. Therefore, it is possible to set the time efficiently. It should be noted that this schedule table does not necessarily have to be represented as a graphic as shown in FIG. 8, and the display of the earth station displays the time when communication is possible, the time zone predicted to be communication, and communication is impossible. It is possible to express the display of various time zones in a message format, and various other expression methods (notification by voice, etc.) are possible.

Next, a concrete method of deciding the place where the communication terminal 7 is installed will be described. First, at the earth station, satellite information such as elevation angle and azimuth angle of the non-geostationary satellite that can be observed from the earth station is derived using the position information of its own station and the orbit information of the non-geostationary satellite obtained by some means in advance. , And the time rate at which each non-geostationary satellite can be used to communicate in each direction (for example, the communication terminal 7 is 180 degrees in eight directions: north, south, northeast, northwest, southeast, southwest). Time ratio in each direction when installed in the field of view). In the situation where the communication terminal (or antenna) of the earth station whose visible space area is limited only to the installation direction is installed in any direction using the available communication time ratio obtained as described above, It is possible to notify in advance the direction in which the highest communication time rate can be achieved. As a method of providing information on the installation direction of the communication terminal 7 to the user who operates the earth station, for example, when the earth station is installed in the direction of the window by having a compass, The method of displaying the communication available time ratio in a direction as a message, the method of issuing a warning to the user with a buzzer sound when the direction in which the communication terminal is installed is in the direction where the communication available time ratio is extremely low, etc. are adopted. be able to.

Furthermore, when the method of utilizing the history of satellite signal reception is applied as a method for the earth station to detect the time zone in which the transmission signal from the non-geostation satellite can be received by the earth station, it is non-stationary. The communicable time rate at the earth station, which is derived over time based on the reception result of the transmission signal from the satellite, is lower than the minimum value of the communicable time rate within a preset unit time. In this case, it is possible to use a method of issuing a warning sound to the user of the earth station or displaying a warning message on the display.

Finally, FIG. 9 shows an example of the structure of an earth station necessary for realizing the present invention. However, FIG. 9 shows only the portion directly related to the present invention, and the devices, circuits and the like normally required for the earth station of the satellite communication system are omitted. In the figure, the visible space region recognition external element 93 can detect the presence or absence of an object existing in the visual field of about 180 degrees as image information 94, and the image information 94 is input to the visible space region recognition device 95. Here, as the external device 93 for recognizing the visible space, various devices such as a general-purpose CCD camera, an infrared device, and a radiometer are used. Next, in the visible space region recognition device 95, the image information 9
4, the visible space area, that is, the skyline from the communication terminal 7 is recognized, and the skyline information 96 is
It is input to the visible space region detection circuit 92 which is a component of the visible space region recognition device 95. Visible space detection circuit 9
In 2, the skyline information is converted into a polar coordinate system centered on the communication terminal 7, and the visible space area information 91 is transferred to the visible satellite detection circuit 90. When realizing the method of the present invention, the visible space area recognition device 95 and the visible space area detection device 92 are used as separate and independent devices from the communication terminal 7, and the visible space area detection device 92 and the communication terminal 7 are connected to each other. It is expected that the operation mode will be connected by cables etc.

On the other hand, the communication terminal 7 can easily calculate the satellite orbit of the non-geostationary satellite shown in FIG. 4 by using the position information of itself and the orbital information of the non-geostationary satellite. The elevation and azimuth of the non-geostationary satellite and the exact time of day located at its coordinates can be known in advance. Here, as means for the communication terminal 7 to acquire the orbit information of the non-geostation satellite, the orbit information of the non-geostation satellite is put on the satellite signal transmitted from the non-geostation satellite, and the communication terminal 7 receives the satellite signal by the antenna 70. Then, after the satellite data receiving circuit 71 detects the information data signal 72, the satellite orbit information detecting circuit 73 can acquire the satellite orbit information 75 and 76. Alternatively, a method of previously writing the orbit information of all non-geostationary satellites in the satellite orbit information storage circuit 82, a method of receiving orbital information transmitted from the non-geostationary satellites and updating the data as necessary, and the like are also used. . In addition, the position information of the communication terminal is derived by the earth station position detection circuit 84 having a positioning function, or the position of the earth station is monitored by the land earth station, and the position information is notified using the communication line in the down direction. However, in the communication terminal 7, various methods such as a method of acquiring the position information 77 of the earth station by the earth station position information detection circuit 74 are used.

Next, in the satellite orbit calculation circuit 81, the satellite orbit information detection circuit 73 or the satellite orbit information storage circuit 82.
Satellite orbit information 75 or 83 and clock 7 given by
Using the absolute time information 80 obtained from No. 9, it is possible to calculate the position of the non-geostationary satellite in the geocentric coordinate system at any time. In the satellite elevation / azimuth calculation circuit 88, the position information 77 of the communication terminal 7 provided from the earth station position information detection circuit 74 or the earth station position detection circuit 84.
Alternatively, by using 85 and the position information 86 of the non-geostationary satellites given from the satellite orbit calculation circuit 81, the satellite elevation angle to all the non-geostationary satellites and the satellite azimuth at any time around the earth station, that is, the communication terminal 7. Can be derived. Further, in the visible satellite detection circuit 90, visible space area information 91 derived from the visible space area detection circuit 92.
And the elevation angle, azimuth, and time information 89 of the non-geostationary satellite derived by the satellite elevation / azimuth calculation circuit 88,
It is possible to detect the azimuth, elevation angle, and time of the contact point between the skyline and the satellite orbit that can be desired from the communication terminal 7. Next, using the contact information 97 between the skyline and the satellite orbit, and the absolute time 87 obtained from the clock 79, the accurate time information 101 and the satellite visible time length detection circuit 99 that enable communication by the satellite visible time detection circuit 98. The satellite visible time length information 102 indicating the continuous communication time and the communication possible time zone from the current time by the current time, and the azimuth time ratio calculation circuit 100, which is obtained when the terminal is installed in an arbitrary azimuth. It is possible to simultaneously derive the respective available communication time ratio information 103. Finally, the information 101, 102, 103 relating to the communication time includes the communicable time display device 104, the communicable time zone display device 105, the communicable time length display device 106, and the azimuth-based time rate display device 1.
07, the operator of the earth station is notified by a display or the like.

[0036]

As described in detail above, the present invention provides the following advantages. (1) Since the time zone in which communication is possible can be grasped in advance, the user of the earth station can efficiently manage the schedule. (2) Even if communication is not possible at the present time, the time when communication is possible next time can be grasped in advance, so that the user can feel secure. (3) When communication is impossible for several hours, the fact is known in advance, so that the user can take action based on his / her own judgment without wasting time. (4) Since the time length during which continuous communication is possible is known in advance, the user can complete the desired communication without disconnection. (5) When the visible space area of the user is limited only to the installation direction of the terminal, the direction having the highest communication time ratio can be detected in advance, so that the user can be guaranteed with high probability of communication. . (6) When the visible space area of the user is limited only to a specific direction, it is possible to inform the user of the direction in which communication is possible with the shortest waiting time.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of an operation mode of satellite communication according to the present invention.

FIG. 2 is a schematic diagram showing an example of an operation mode of satellite communication according to the present invention.

FIG. 3 is a diagram showing a specific example of a visible space region in an earth station according to the present invention.

FIG. 4 is a diagram showing an example of a satellite orbit of a satellite communication system using non-geostationary satellites according to the present invention.

FIG. 5 is a diagram showing an example of a satellite orbit that enables communication according to the present invention.

FIG. 6 is a diagram showing an example of a schedule table of communication time created according to the present invention.

FIG. 7 is a diagram showing a specific example of a method for determining a satellite orbit that enables communication according to the present invention.

FIG. 8 is a diagram showing an example of a schedule table of communication time created by the method for determining a satellite orbit that enables communication according to the present invention.

FIG. 9 is a block diagram showing an embodiment of an earth station according to the present invention.

[Explanation of symbols]

 1, non-geostationary satellite 3-5 building 6 window 7 communication terminal 8, 9 satellite signal 10 external element for visible space area recognition 11 visible space area recognition device 12-14 satellite signal blocking area 20-34 satellite orbit 40-51 satellite Part of orbit 52,53 Visible satellite azimuth 60 Satellite signal reception start state 61 Satellite signal reception start time 62 Several minutes after satellite signal reception start 63 Hours after satellite signal reception start 64 Communication time schedule table completed State 65 Time when communication is possible 66 Time when communication is not possible 67 Time when communication is likely to be performed 68 Time when communication is unlikely to be performed 69 Time when communication is not possible 70 Antenna 71 Satellite signal receiving circuit 72 Information data Signal 73 Satellite orbit information detection circuit 74 Earth station position information detection circuit 75,76 Satellite orbit information 77 Earth station position information 79 Clock 80 Absolute time information 81 Satellite orbit calculation circuit 82 Satellite orbit information storage circuit 83 Satellite orbit information 84 Earth station position detection circuit 85 Earth station position information 86 Satellite position information 87 Absolute time information 88 Satellite elevation / azimuth Calculation circuit 89 Satellite elevation / azimuth / time information 90 Visible satellite detection circuit 91 Visible space area information 92 Visible space area detection circuit 93 External element for visible space area recognition 94 Image information 95 Visible space area recognition device 96 Skyline information 97 Skyline-satellite Orbital contact information 98 Satellite visible time detection circuit 99 Satellite visible time length detection circuit 100 Directional time rate calculation circuit 101 Satellite visible time information 102 Satellite visible time length information 103 Directional time rate information 104 Communication time display device 105 Communication time Band display device 106 When communication is possible Long display 107 orientation by time ratio display device

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroyasu Ishikawa 2-3-2 Nishishinjuku, Shinjuku-ku, Tokyo International Telegraph and Telephone Corporation

Claims (5)

[Claims] 1. A non-geostationary satellite having a function of communicating with the ground, an earth station having a transmitting / receiving device capable of communicating with the non-geostationary satellite, and communication with the earth station connected to a ground communication network. In a satellite communication system composed of a land earth station capable of performing the operation via the non-geostationary satellite, a visible space region in which a transmission signal transmitted from the non-geostationary satellite can be received by the earth station, that is, the earth. Non-stationary observable from the earth station derived by using the information about the visible space area, the position information of the earth station, and the orbit information of the non-geostationary satellite by detecting the skyline of the station by the earth station itself. By using satellite information such as elevation angle and azimuth angle of the satellite, the passing time of the non-geostationary satellite at which the transmission signal from the non-geostationary satellite can be received at the earth station is grasped before the start of the communication, And information about the time zone during which communication between the non-geostationary satellite and the non-geostationary satellite becomes possible, and the time, time zone, and available time at which satellite communication using the earth station becomes possible for the user of the earth station. A communication time notification system for satellite communication characterized by being configured to be able to provide information such as a time rate. 2. An aerial part observable from the earth station and structures and trees on the ground as a method for the earth station to detect a space visible region in which a transmission signal transmitted from a non-geostationary satellite can be received by the earth station. , Based on the information about the skyline, the position information of the earth station, and the orbit information of the non-geostationary satellite, using a means for detecting the skyline from the earth station, which is a boundary line with a shielding object such as a hilly area. By using satellite information such as elevation angle and azimuth angle of the non-geostationary satellite that can be observed from the earth station, the passing time of the non-geostationary satellite that can receive satellite signals at the earth station is grasped before the start of the communication. The communication time detection method for satellite communication according to claim 1, wherein information about a time zone during which communication between the earth station and the non-geostationary satellite is possible is detected. 3. A history of whether or not a transmission signal transmitted from the non-geostation satellite is received is used as a method for the earth station to detect a time zone in which the transmission signal transmitted from the non-geostation satellite can be received by the earth station. When recorded at the earth station and a transmission signal from a specific non-geostationary satellite can be received,
The satellite elevation angle and satellite azimuth from the earth station to the specific non-geostationary satellite at that time are detected in the earth station by using the position information of the earth station and the orbit information of the non-geostationary satellite, Recognizing that the transmission signals of all non-geostationary satellites having the same satellite azimuth and a satellite elevation angle higher than that of the particular non-geostationary satellite are receivable at the earth station, at the same time, the corresponding non-geostationary satellite becomes the particular non-geostationary satellite. When the time when the satellite arrives in the direction of the satellite is detected as the communication available time and the transmission signal from another specific non-geostationary satellite cannot be received, the other specific non-stationary from the earth station at that time is detected. Transmission of all non-geostationary satellites that have detected the satellite elevation and satellite orientation to the satellite at the earth station and have the same satellite orientation as the other particular non-geostationary satellite and have a satellite elevation angle lower than the other particular non-geostationary satellite. The signal is At the same time that the non-geostationary satellite recognizes that it cannot receive at the earth station, it detects the time when the corresponding non-geostationary satellite arrives at the satellite direction of the other specific non-geostationary satellite as the communication-disabled time, and the earth station transmits the satellite signal. Grasping the transit time of receivable non-geostationary satellites over time,
The communication available time notification system for satellite communication according to claim 1, wherein information about a time zone during which communication between the earth station and the non-geostationary satellite is possible is detected. 4. A non-geostationary satellite having a communication function with the ground, an earth station having a transmitter / receiver capable of communicating with the non-geostationary satellite, and a ground communication network,
In a satellite communication system composed of a land earth station capable of communicating with the earth station via the non-geostationary satellite, the satellite communication system is derived using position information of the earth station and orbital information of the non-geostationary satellite. Using the satellite information such as elevation angle and azimuth angle of non-geostationary satellites that can be observed from the earth station, the earth station is installed in a place where the visible space region is limited to a specific direction. Derivation of the communicable time ratio in each direction from the station installation location and notifying the user of the earth station of the direction capable of achieving the highest communicable time ratio before the start of the communication, or regarding all the directions A communication available time notification system for satellite communication, which is configured to notify the communication available time rate before the start of the communication. 5. The communicable time ratio in the earth station, which is derived over time based on the reception result of a transmission signal from a non-geostationary satellite, is within an arbitrary unit time set before the start of the communication. 4. The satellite communication available time notification system according to claim 3, which is configured to issue a warning to a user of the earth station when the available communication time ratio is below the minimum value.