JP2000036786A - Artificial satellite of orbit with long stay time in direction of zenith, orbit control method therefor and communication system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish a communication line, which is not affected by any artificial construction or plant, with a moving object or fixed station inside the construction surrounded with high-rise buildings, to efficiently perform image transmission from the moving object, the automatic charging of public utility rates or mountainous disaster rescue, while using his communication line and to compose a system of much less satellites to provide inexpensive satellite services. SOLUTION: Six orbit elements 11, 12, 13, 14, 15 and 16 are determined with the geographical conditions of a service object area (step 3), required service time (step 2) and the allowable range of elevation angle, capable of watching an artificial satellite from the service object area (step 1) as input conditions, and plural elliptic orbits with long time for the artificial satellite to stay in the direction of the zenith are combined corresponding to the six determined orbit elements, and satellite communication is performed, while using a satellite group constituted by arranging one or more satellites appropriately on that orbit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial satellite,
In particular, the present invention relates to an artificial satellite that can be used in communication fields such as satellite communication and mobile communication, its orbit, and its orbit control method.

[0002]

2. Description of the Related Art Conventionally, medical data relating to an emergency patient being transported from an ambulance is transmitted to an emergency medical center in the form of an image, and an appropriate medical treatment instruction is to be given from the emergency medical center during transportation. And needs.

However, when a large amount of data such as images is to be transmitted from a mobile body such as an automobile, the terrestrial communication infrastructure cannot cope with it. Even through a geostationary satellite currently in service in orbit or a mobile communication satellite scheduled to start a service, it is difficult to transmit from a mobile for a long time due to a shield such as a building or a grove.

[0004] A large amount of data transmission from a mobile body such as an automobile is possible with a satellite using a special orbit.
The specific method of finding the orbit has not been established. Therefore, no solid concrete proposal has been made for the orbital element of the special orbit.

[0005]

The prior art and problems will be specifically described below based on known examples.

(A) Existing Communication Infrastructure Technology and Problems (A-1) Terrestrial Communication Infrastructure Technology and Problems When a large amount of data such as images is transmitted from a mobile body such as an automobile to a fixed station on the ground, Communication via terrestrial communication infrastructure or communication satellites is conceivable, but what currently exists does not satisfy all of its requirements.

The case of an ambulance will be described as an example. For the transport of ambulance patients by ambulance, the current average transport time is
There are about 27 minutes. In the case of severely ill patients, there are many cases of death without proper treatment during this time, and there is a need for appropriate treatment or guidance of treatment by a specialist during emergency transport. However, in order for physicians to always be on board 5,000 ambulances nationwide, about 15,000 or more full-time physicians are required considering shift work, which is not practical, and intensive instructions are given from the emergency center etc. It is efficient to do. However, in the current terrestrial communication system, only telephone-level communication that is apt to be interrupted is realized, and instructions for appropriate treatment from an emergency center cannot be sufficiently performed. It is said that if image information such as an endoscope, an electrocardiogram, an echo, and a camera is sent to an emergency center, considerable diagnosis and treatment instructions can be made. However, the terrestrial communication infrastructure has limited transmission bandwidth,
There are many problems such as limitations on the communicable area, crosstalk with other communications, and interference due to reflections on artificial structures, and practical application is difficult.

[0008] Similarly, there are many demands for transmission of a large amount of data from a mobile body, such as a marathon television relay, but the current ground communication infrastructure cannot cope with the demand.

(A-2) Technology and Problems of Geosynchronous Communication Satellite System In satellite communication using artificial satellites, those using a geostationary satellite and those using a medium to low altitude orbit are known. Conventional communication satellites have the following problems.

Since a geostationary satellite has a period of about 24 hours, which is almost the same as the earth's rotation period, it appears to be stationary above the equator from the ground. However, in general, the elevation angle is low, and even in good conditions, the elevation angle in Tokyo is about 45 degrees. Moving objects in urban areas pass through roads surrounded by man-made structures such as buildings and tree-lined trees, so low elevation angles are obstructed by these objects, and satellite communications by geostationary satellites tend to be obstructed. is there. Since the geostationary satellite is seen from the southeast to the southwest, if you are moving in the north-south direction, you can communicate because the field of view of the geostationary satellite is open, but if you are moving in the east-west direction, especially in the west direction. When moving, communication is interrupted due to artificial buildings and tree-lined trees during a considerable period of time. Accordingly, satellite communication using geostationary satellites has not been satisfactory in non-flat areas such as urban areas and mountainous areas.

(B) Technologies and Problems of Satellite Communication Systems Under Development Currently, satellites using medium or low altitude orbits, such as Iridium and Odyssey, which are being realized for mobile phone services using mobile communication satellites In the case of a communication system, the time period during which a communicable satellite stays at a high elevation angle when viewed from the ground is generally short due to restrictions such as the number of orbital planes of the satellite and the number of satellites. In particular, a low-orbit satellite orbits around the earth with an orbital period of about 90 to 100 minutes, so that it only stays at a high elevation angle when viewed from the ground for about a few minutes. Therefore, when trying to communicate a large amount of data for a certain period of time (for example, 27 minutes or more) without being interrupted by obstacles such as artificial buildings, plants, and natural terrain, as in the example of the above-mentioned ambulance, In order to apply or apply these satellite communication systems, a system must be used in which satellites are constantly changing in high elevation directions. In that case, several hundred or more satellites are required, and considering the procurement problems of the satellites themselves, their operation costs, launch costs, and the like, it must be said that they are not economically feasible.

As described above, when a high elevation angle is required, geostationary satellites which have been put into practical use up to now, and low-to-medium-altitude satellites which are currently being put into practical use are inadequate.

(C) Techniques and problems of the satellite communication system in the research stage. For example, IEICE Technical Report (IEICE Technical Report) Vol.
89, No. 57, "Possibility of mobile communications mission using non-geostationary satellite orbit" and other research reports discuss satellite communication systems currently in the research stage. In particular, a long elliptical orbit with a large eccentricity has been proposed, including the above research report.

According to Kepler's law, the speed on the orbit becomes slow near the apogee. This is because if this is used to set an orbit where the apogee comes above the service target area, the satellite can stay longer in a high elevation angle range. Therefore, it is essential to use a long elliptical orbit in order to secure a communication line for a long time without causing a communication interruption due to an artificial structure, a plant, or a natural topography.

As an example of a long elliptical orbit, for example, in Russia, the perigee altitude is several hundred km and the inclination of the orbit is about 12 hours in a period of about 12 hours.
A 63.4 degree Mornier orbit has been in service since the 1960s for communications satellites and military reconnaissance satellites in Russia. This orbit is a stable orbit with a fixed perigee argument in the orbital plane, but it is practical in Russia where the land is distributed at high latitudes, but has a wide spread north and south at low latitudes In Japan, it is an orbit that is less practical.
In Japan, some orbits having a period of approximately 8 hours, orbits having a period of approximately 12 hours, and orbits having a period of approximately 24 hours have been proposed. However, these proposals are only point designs, and specific orbits that are suitable for the Japanese territory that spreads in the north-south direction and east-west direction are also proposed for the optimal orbit and how to set the orbit. And no solution has been presented. This is probably because the method of determining the six elements of the trajectory by analogy based on the experience of the designer was generally used for setting the trajectory.

There are various parameter setting methods for defining the trajectory. Generally, the following six trajectory elements are often used. These are defined as values at a certain reference time, orbit major axis a: major axis of ellipse (indicated by 54 in FIG. 5) Eccentricity e: flatness of ellipse (0 ≦ e <1) orbit inclination angle i: orbit Of the plane from the equatorial plane (64 in Fig. 6)
(Shown by 0 ° ≦ i ≦ 180 °) Ascending Ascension Ω: Angle measured from the vernal equinox to the east from the point where the orbit crosses the equatorial plane from the southern hemisphere to the northern hemisphere (ascending intersection, indicated by 62 in FIG. 6) (Shown by 63 in FIG. 6) (0 degree ≦
Ω ≦ 360 degrees) Perigee argument ω: Angle of perigee position on the orbital plane measured from ascending intersection 62 (indicated by 63 in FIG. 6) (0 degree ≦ ω ≦ 360 degrees) True near-point separation angle θ: Perigee The angle formed by the line connecting the focus of the ellipse, the position of the satellite in orbit, and the line connecting the focus of the ellipse (Fig. 5
(58 degrees) (0 degrees ≦ θ ≦ 360 degrees) is often used. These geometric relationships will be described with reference to FIGS. Satellite 51 is the focus of the ellipse
Move 50 as the focal point of the elliptical orbit. The distance between the perigee 53 of the ellipse and the focal point 50 of the ellipse is represented by the perigee radius Rp, and is represented by 57 in FIG. The distance between the apogee 52 of the ellipse and the focal point 50 of the ellipse is represented by the apogee radius Ra, and is represented by 56 in FIG. Perigee radius Rp, apogee radius Ra, orbital major radius a, FIG.
There is the following relationship between the short radius b of the orbit indicated by 55 and the eccentricity e.

Rp = a (1-e) Ra = a (1 + e) b = a (1-e2) 1/2 e = (Ra-Rp) / (Ra + Rp) In FIG. Here is an example of the case. The elliptical orbit crosses the equatorial plane 61 at the ascending intersection 62 from the southern hemisphere toward the northern hemisphere. The angle 64 between the equatorial plane 61 and the orbit plane is the orbit inclination angle i. The ascending node RA is defined by an angle 68 measured eastward from the vernal equinox direction, and the perigee argument is defined by the angle 63 from the ascending node 62 to the perigee 65.

Even if the orbital major radius can be selected from the orbital period, the eccentricity, which is a main parameter of other orbitals, is 0.
Any real number from 0 to less than 1.0, orbit inclination angle from 0.0 degree to 18
Any real number less than 0.0 degrees, perigee argument is more than 0.0 degrees 360.0
Since any real number less than degree can be selected, considering these combinations, there are infinite combinations of orbital elements. Therefore, there are aspects in which the designer must set those parameters intuitively or by analogy from his own experience.

If a trajectory that can be seen for a long time in the zenith direction of the service target area can be realized, "large-capacity data transmission from a mobile unit for a long time" is realized by communication via a satellite. Therefore, there is a need for specific setting values of orbital elements and specific methodologies for setting the orbital elements, which are adaptable to the national land of Japan and have economical efficiency, that is, the number of satellites constituting the entire system is as small as possible. I was

As described above, in order to transmit a large amount of data such as image data from a mobile body such as a car for a long time, the artificial satellite is arranged in the zenith direction so as to be visible as long as possible. Communication via satellite is required.

In order to realize this, it is generally considered that a long elliptical orbit in which the apogee is located above the service target area is preferable. However, a firm method has been proposed for an appropriate setting method and algorithm of the orbital element. Not. In addition, there is no specific proposal for an appropriate orbital element when, for example, the whole of Japan is to be served.

The present invention has been made in view of the above problems, and presents a specific methodology devised for setting the orbital element, and limits the range of the orbital element obtained using the method. The purpose is to set.

Still another object of the present invention is to construct various systems using artificial satellites arranged so as to be visible in the zenith direction for a long time so that the above problems can be solved. And

Still another object of the present invention is to provide orbit control means for controlling the orbit of an artificial satellite based on the orbital elements set as described above.

[0025]

In order to achieve the above object, according to the present invention, in an artificial satellite orbiting in an elliptical orbit, the elliptical orbit is provided with a service target area provided by using the artificial satellite, It is assumed that the orbit is defined by the six orbital elements obtained as input conditions of the allowable range of the elevation angle at which the artificial satellite can be seen from the service target area and the reference time defining the orbital element.

Here, the satellite in the elliptical orbit according to the present invention is:
The satellite orbits a long elliptical orbit where the satellite can be seen at an angle greater than the maximum elevation angle when the geostationary satellite is viewed from the service target area of the satellite.

More specifically, when determining the orbital element, the orbital major radius setting step, the perigee argument setting step, the half apex angle setting step, the required service time setting step, and the service target area are included. A polygon setting process, a setting process of the number of satellites and an ascending intersection of each satellite and an ascending intersection of each satellite, a setting process of an initial value of an orbit inclination angle, a calculation process of a visible time from each vertex of the polygon, The six elements of the orbit are determined by the step of setting the combination of the orbit inclination angle and the eccentricity, and the step of resetting the ascending ascension of right ascension and the near point declination.

In order to achieve the above object, according to the present invention, in an artificial satellite group consisting of a plurality of artificial satellites orbiting in an elliptical orbit, the orbital six elements of the elliptical orbit of each of the artificial satellites are The target area of the service performed using the above, the allowable range of the elevation angle at which any of the artificial satellites of the artificial satellite group can be seen from the service target area, and the reference time defining the orbital element are obtained as input conditions. A plurality of the elliptical orbits are combined so that at least one or more satellites are always visible within a predetermined elevation angle range in the zenith direction viewed from the service target area, and one or more elliptical orbits are provided on each orbit plane. A group of artificial satellites is used in which more than two satellites are arranged.

Further, in order to achieve the above object, the present invention provides:
Systems that use various artificial satellites, such as an orbit control system for controlling the orbit of artificial satellites, a satellite communication system that performs satellite communication via artificial satellites, and an earth observation system that uses artificial satellites equipped with earth observation devices In the above, the artificial satellite provided with the orbit according to the present invention is used.

Here, when the satellite communication terminal in the satellite communication system is used in the service area targeted by the artificial satellite according to the present invention, the artificial satellite appearing within a predetermined elevation range in the zenith direction. It is provided with a transmission / reception means for transmitting / receiving a signal to / from a satellite, and may be mounted on a moving object mainly moving in the service target area. In addition, for satellite communication terminals, GPS means that receives radio waves from GPS satellites that compose the global positioning system and at least measures its own position, and those that are subject to utilities such as electricity, gas and water, etc. A measuring means for measuring the usage amount for each house may be further provided.

According to another aspect of the present invention, there is provided a method for determining an orbital element of an artificial satellite orbiting in an elliptical orbit, comprising: a service target area provided by using the artificial satellite; Then, the orbital six elements satisfying the input conditions are obtained using the allowable range of elevation angle at which the artificial satellite can be seen and the reference time defining the orbital elements as input conditions. When a plurality of artificial satellites are arranged, the plurality of elliptical orbits are arranged so that at least one or more artificial satellites are always visible within a predetermined elevation range in the zenith direction viewed from the service target area. It is preferable to combine one or more satellites on each orbital plane.

Further, the above-mentioned object is to provide a means for setting a polygon including an orbital major radius, a perigee argument, a half apex angle, a service period, and a service target area, and from the set values, the number of satellites and each Means for setting the ascending intersection of the ascending intersection of the satellite and the near-point separation angle, means for setting the initial value of the orbit inclination angle, means for calculating the visible time from each vertex of the polygon, and orbit inclination angle And a means for setting a combination of the eccentricity and the eccentricity, and a means for resetting the ascending right ascension and the near-point departure angle.

According to another aspect of the present invention, there is provided a satellite communication system for performing satellite communication via an artificial satellite, comprising: an artificial satellite; and a satellite communication terminal for performing satellite communication via the artificial satellite. A base station that communicates with the satellite communication terminal via the artificial satellite, wherein the artificial satellite is higher than the maximum elevation angle of the geostationary satellite viewed from the service area of the artificial satellite. An artificial satellite orbiting a long elliptical orbit so that the artificial satellite can be seen at an elevation position, wherein the satellite communication terminal can be mounted on a mobile object and is used in a service target area targeted by the artificial satellite. A transmission / reception unit for transmitting / receiving a signal to / from the artificial satellite that appears within a predetermined elevation angle range in the zenith direction.

According to another aspect of the present invention, there is provided a satellite communication system for performing satellite communication via an artificial satellite, comprising: a plurality of satellite communication systems for performing satellite communication via the artificial satellite; At least a terminal, wherein the artificial satellite orbits a long elliptical orbit in which the artificial satellite can be seen at an angle position larger than the maximum elevation angle of the geostationary satellite viewed from the main service target area of the artificial satellite. A plurality of satellite communication terminals, each of the plurality of satellite communication terminals includes transmission / reception means for transmitting / receiving a signal to / from another satellite communication terminal via the satellite. At least one of them is located in the main service target area, and the other is in a place other than the main service target area and capable of satellite communication with the artificial satellite. And relays between satellite communication terminals located in the main service area according to the elevation angle of the satellite as viewed from the main service area of the artificial satellite, the main service area. In the relay between the satellite communication terminal in the satellite communication terminal located in the other area and the relay between the satellite communication terminals located in the area other than the main service target area, any of the relay modes is selected. You.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is applied to: a method (algorithm) for setting an appropriate trajectory element; setting of a trajectory element by the algorithm; and realization and control of the set trajectory element. The following describes the embodiments in order.

(1) Method for Setting Appropriate Orbital Elements (Algorithm) In order to make the satellite appear long in the zenith direction that is less obstructed by artificial structures, plants and natural terrain, An elliptical orbit with an apogee above the area is effective. Here, the method of setting the orbital element according to the present invention will be described in order. This setting method is shown in the flowchart of FIG.

(1-1) Setting of the major radius of the orbit (Step 4) Considering the operation of the satellite itself and the operation of satellite communication using the satellite, the integral multiple of the length of the day or the integral multiple of the day is considered. If a periodic orbit is adopted, the same satellite will be visible every day in the same time zone, so periodic operation will be possible. Table 1 shows an example of the result of the visual analysis of the satellite when the orbit period is set to 4, 6, 8, 12, 16, 24, 32 and 36 hours.

[0038]

[Table 1]

When the orbital inclination angle of each orbit is 63.4 degrees, the length of time the satellite can be seen from each city in the zenith direction with an elevation angle of 70 degrees or more is arranged, but it is overwhelmingly 12 and 24.
It can be seen that selecting a satellite orbit with a time period is advantageous in terms of the system configuration. Therefore, even if the orbit inclination angle changes,
In particular, an orbit having a cycle of about 12 hours or a cycle of about 24 hours can be determined to be practical. The orbital radius 11 is about 26,562 km or about 24 for an orbit with a cycle of about 12 hours from the cycle of the satellite.
If it is an orbit with a period of time, it is uniquely determined as about 42,178 km.

(1-2) Setting of Perigee Argument (Step 5) The perigee argument 12 depends on the location of the target area to receive the communication service using the satellite or the earth observation service. If the target area is the northern hemisphere, the perigee is The perigee argument is about 270 degrees so that it is over the southern hemisphere and the apogee is over the northern hemisphere.
Similarly, if the service target area is the southern hemisphere, the perigee argument may be about 90 degrees. These are indispensable conditions for arranging the apogee above the service target area.

(1-3) Setting of Eccentricity, Orbit Inclination Angle, Ascending Right Ascension and Right-Angle Eccentric Angle (a) Setting of Half-Apex Angle (Step 1) First, the zenith direction is qualitative. Therefore, the allowable range from the zenith direction as the direction in which the satellite can be seen, such as 20 degrees or 40 degrees, is determined by the half apex angle. At this time, the elevation angles are 70 degrees and 50 degrees, respectively. The satellite is visible for a long time in a cone centered on the zenith formed by this half apex angle. Obviously, the smaller the half apex, the more absolute number of satellites to service.

(B) Setting of Required Service Time (Step 2) The length of time for receiving service by the satellite is set. For example, in the case of an ambulance, 24-hour continuous service is required.

(C) Setting of a polygon encompassing the service area (step 3) Since a conventional geostationary satellite looks stationary from the ground, it can be handled by forming an antenna beam for the service area. Was. In addition, Iridium using medium-to-low altitude orbit
And systems such as Odyssey use a design philosophy that covers the ground in sequence with many satellites,
There was no need to consider in detail the service target area. However, the current target elliptical orbit does not always look stationary from the ground, and it is preferable that the number of satellites be small. Therefore, it is necessary to select a track shape suitable for the service target area.

In the present invention, first, the latitude, longitude and height of the four points at the northernmost, southernmost, westernmost, and easternmost points of the service target area are given. In the case of Japan, the points shown in Table 2 are considered as the northernmost, easternmost, southernmost, and westernmost points.

[0045]

[Table 2]

These four points are scattered as shown in FIG. 7, and their latitude and longitude generally do not take the same value. If the service area is not included in the quadrangle with these four points as vertices, consider a polygon that includes all of the service areas and consider the latitudes of the vertices other than these four points,
Set longitude and altitude. This polygon may be formed such that a plurality of triangles are adjacent to each other.

The steps (a) to (c) described above may be performed in any order.

(D) Setting of the number of satellites and the ascending intersection of each satellite and the right ascension and departure angle (Step 6) If 24-hour continuous service is provided by elliptical orbit, it cannot be realized by one satellite Is clear. Therefore, the number of satellites required to configure the system, such as two or three, is set. In order to continuously service a certain area, it is effective to arrange satellites one by one in one orbit plane. It is desirable that the orbits have the same shape. The right ascension of each orbit should be separated by 360 degrees divided by the number of satellites. That is, if the number of satellites is three, the ascending intersection RA is 12
The satellite will move on three orbital planes separated by 0 degrees.

The ascending node of right ascension rotates at a constant period around the earth axis under the influence of the gravitational potential of the earth. That is, the orbital plane rotates around the earth axis. Therefore, the ascending intersection RA must be defined at the reference time so that the apogee is over the service target area. At this stage, any numerical value convenient for analysis may be given. Also, the position of the service target area in the inertial space may be given any value convenient for analysis.

In setting the near-point separation, when one satellite is at perigee in its orbit, the near-point separation of the other satellites is obtained by dividing the period by the number of satellites constituting the system. It is sufficient to separate them by an angle corresponding to the time taken. For example, in the case of three aircraft, it is sufficient that the satellites in adjacent orbits are separated from each other in order of 1/3 of the orbital period.

By setting the ascending intersection RA and the right-neighbor separation angle, the ground trajectories of each orbit almost coincide with each other, and the satellites can appear over the same area in order.

(E) Setting of the initial value of the orbit inclination angle (Step 7) If the apogee of the orbit comes above the vicinity of the center of gravity of this polygon, it is considered that a substantially uniform service can be provided in the whole service target area. . However, this arrangement is not always ideal because of movement of each point due to rotation and relative movement due to orbital movement of the satellite. Therefore, the analysis is performed as follows with the orbit inclination angle having the same angle as the latitude near the center of gravity of this polygon as the initial value.

(F) Calculation of Visible Time from Each Vertex of Polygon (Steps 8 and 9) The orbital major radius 11 of each orbit, perigee argument 12, ascending right ascension, right near point departure, and orbit The initial value of the tilt angle is determined. In other words, five of the six elements are determined.

The time at which the satellite can be seen inside the cone defined by the half-vertical angle in the zenith direction from each point of the polygon is determined for each satellite. This is obtained by geometric calculation and Kepler's law, but can also be calculated by a computer. As shown in step 8 of FIG. 1, by changing the eccentricity from 0.0 to 1.0, a range of the eccentricity in which the visible time length from each point of the polygon is substantially the same is obtained. In the case of using a computer, a method of sequentially changing the eccentricity at a finite step size and comparing the visible time from each vertex of the polygon is considered.

Next, as shown in step 9 of FIG. 1, the trajectory inclination angle is slightly changed from the initial value, the eccentricity is similarly changed, and the visible time from each point of the polygon becomes substantially the same time length. Find the range of eccentricity. Similarly, when a computer is used, a method of changing the inclination angle of the trajectory by a finite step width and comparing the visible time from each vertex of the polygon may be considered. Determine the reference time, determine the ascending intersection of the right ascension and the position in the inertial space of the service area in accordance with this, then propagate it in orbit with a computer, and calculate the visible time within the time range, each satellite will overlap. Then, the time at which it can be seen inside the cone formed by the half apex angle in the zenith direction is also required.

At this time, the length of time during which the satellite stays inside the half apex angle is the length of time that one satellite can service per orbit plane, and is a divisor of about 24 hours, which is the rotation cycle of the earth. , About 1, about 2, about 4, about 6, about 8, about 12, and about 24 hours, which are convenient because service and satellite operation can be performed periodically. Obviously, in order to provide services 24 hours a day, that is, without interruption, it is necessary to have at least one satellite if this time is about 24 hours and at least two satellites if it is about 12 hours. I understand. Therefore, based on this, if necessary, the process returns to the above-mentioned step (d) (step 6) to redefine the number of satellites.

(G) Setting of Combination of Orbit Inclination Angle and Eccentricity By repeating the analysis shown in steps 8 and 9 above, a uniform service can be provided at all points of the polygon including the service target area. The values of the trajectory inclination angle and the eccentricity are combined to obtain a numerical value range as shown in FIGS.

(H) Resetting of the ascending intersection right ascension and the right angle separation (step 10) Finally, a reference time is set in accordance with the launch time of the satellite, etc., and an appropriate ascending intersection red according to the time is set. The meridian 15 and the near-point separation angle 16 may be set.

A program corresponding to all or a part of the above algorithm may be generated and executed by a computer. For example, after the user inputs the data set in steps 1 to 5, the program corresponding to steps 6 to 10 may be executed by the computer based on these setting conditions.

(2) Setting of orbital elements by the above algorithm (2-1) When Japan is the service target area By using the above method (algorithm), in the area including all territories of Japan, The elliptical orbit of the orbital element shown in Case 2 is obtained as a combination of the orbital element range in which one satellite is visible for about 12 hours per day in the zenith direction with an elevation angle of 55 degrees or more from all over Japan. At this time, if the two satellites are arranged 180 degrees apart from the ascending intersection of right ascension and 180 degrees apart at the near point departure, which is half the orbital period, the zenith with an elevation angle of 55 degrees or more continuously for 24 hours a day It becomes visible from all over Japan in the direction.

In addition, when considering the whole of Japan except for remote islands off the southern sea, such as offshore Torishima and Minamitorishima, 4
Case 1 in Table 3 with the right ascension of two satellites separated by 90 degrees
By using the elliptical orbit of the orbital element shown in (1), any satellite can always be visible in the zenith direction with an elevation angle of 70 degrees or more.

[0062]

[Table 3]

The orbit of the satellite is the earth's gravitational field,
Due to the influence of the sun's attraction and the like, it constantly fluctuates even in a short cycle and a long cycle, and is generally controlled with a certain allowable range. For this reason, the approximate values or the target nominal values after the orbit control are indicated for the orbital elements discussed in this specification and tables.

In the case of an orbit having a period of about 12 hours, the elliptical orbit of the orbital element shown in Case 3 of Table 4 is expressed in Hokkaido, Honshu, Shikoku,
Obtained in Kyushu and Okinawa as a combination of orbital elements that make the satellite visible in the zenith direction with an elevation angle of 70 degrees or more for about 6 hours.

[0065]

[Table 4]

When an orbital element other than the above range is selected, for example, in case 2 of an orbit with the above period of about 24 hours, a satellite is moved in a zenith direction with an elevation angle of 55 degrees or more in some areas of Japan. In some cases, it becomes invisible. For example, if the orbital inclination angle is 45
If it is less than 135 degrees or greater than 135 degrees, the northernmost service time will be less than 24 hours a day,
Conversely, if the inclination of the orbit is 55 degrees or more and 125 degrees or less, the service time at the southernmost end will be less than 24 hours a day. If the eccentricity is less than about 0.25, it is the northernmost point, and if it is about 0.38 or more, it is the westernmost point and the easternmost point. FIG. 8 shows that the eccentricity is about 24 hours and the eccentricity is 0
FIG. 9 shows the ground trajectory of a trajectory for a trajectory having a trajectory of 25 and an orbit inclination of 55 degrees and a perigee argument of 270 degrees. Shows the ground trajectory of the orbit for the 270 degree orbit. Ground trajectory spreads east-west as eccentricity increases,
As the inclination of the orbit increases, the inclination of the orbit becomes 0 to 90 degrees.
When the inclination angle is in the range of 90 to 180 degrees, it spreads in the north-south direction as it becomes smaller. From the comparison of the ground trajectory shown in the drawing, it can be understood that the service is incomplete at any point when the vehicle goes out of the range of the orbital element given earlier.

From the above, the range of orbital elements suitable for covering the whole of Japan is summarized in Table 5. As an example,
The service target area, allowable elevation angle, and required number of satellites set for each case are added.

[0068]

[Table 5]

(2-2) When the whole world is targeted When the whole world is targeted for service, the whole world is divided into regions of a fixed area, and the above concept is applied to each region. Just do it. In some cases, it is better to use a geosynchronous trajectory than an elliptical trajectory for the area near the equator. Is effective. For example, the whole world can be covered by combining a plurality of elliptical orbits of the orbital elements shown in Table 6 and further combining geostationary satellites.

[0070]

[Table 6]

As described above, the ground trajectory of the orbit expands in the east-west direction by increasing the eccentricity, and the ground trajectory of the orbit expands in the north-south direction by increasing the inclination angle of the orbit. Inside the orbit of the ground orbit, especially near the center, there is an area where no service can be received from the satellite at this time. This can be solved by arranging orbits that are adjacent to each other on the ground track so that the ground tracks overlap as shown in FIG.

(3) Measures for Realizing and Controlling the Set Orbital Element The orbit of the artificial satellite having the orbital element set in this way is controlled and realized as follows.

As shown in FIG. 2, when the artificial satellite 20 is launched, the information of the six orbital elements 17 suitable for the service target area previously set is input to the launch vehicle tracking control equipment 21, and from there, the launch vehicle is controlled. Information on the target input trajectory element 22 is transmitted. The launch vehicle 23 is put into a target orbit automatically based on this information or under the control of the tracking control equipment 21.

After the artificial satellite 20 is put into orbit, the information of the six orbital elements 17 suitable for the service area is periodically input to the artificial satellite tracking control equipment 18, and the information of the control command 19 is transmitted to the artificial satellite 20. The transmitted orbit is controlled by the control system mounted on the artificial satellite 20 to the target six orbital elements 17.

Since this trajectory control method conforms to a commonly used method, the details will be described later.

Next, more specific examples of the above embodiments will be described. In the present invention, there are two concepts of an orbital element obtained by the algorithm of the present invention and its range; a system to which a satellite moving in the orbit is applied; This is described separately. Subsequently, a specific example of a measure for actually controlling the six elements of the orbit of the satellite to the one suitable for the service target area will be described.

(4) Orbital elements obtained by the algorithm of the present invention and their ranges (4-1) Orbital arrangement example 1 This orbital arrangement example covers the whole of Japan. The orbit of an artificial satellite fluctuates constantly due to the influence of the earth's gravitational field, the gravitational pull of the moon and the sun, and the orbit is generally controlled with a certain tolerance. Therefore, the value of each trajectory element shown in each trajectory arrangement example below indicates a target nominal value after trajectory control.

In this orbit arrangement example, there are two orbit planes as shown in FIG. 11, and one satellite 110 and one satellite 111 are arranged on each orbit. The satellite 110 makes an orbit around the orbit 112 in about 24 hours, and the satellite 111 makes an orbit around the orbit 113 in about 24 hours. The orbital period of satellites 110 and 111 is about 24 hours,
The eccentricity is in the range of 0.24 to 0.38, the orbit inclination angle is in the range of 47 to 52 degrees or 128 to 133 degrees, and the perigee argument is 270 degrees.
The ascending intersection of the two satellites is 180 degrees apart, as shown in Figure 11, so that the apogee appears at an appropriate position above Japan. The relative positions of the respective satellites in their respective orbits are such that when the satellite 110 is at perigee on its orbit 112, the satellite 111 is located at apogee on its orbit 113. This orbital arrangement is obtained by an outline of the algorithm shown in FIG. 1, and is realized by the control method shown in FIG.

With this orbital arrangement, the elevation angle in all of Japan including the northernmost, southernmost, easternmost, and westernmost ends of Japan
In this arrangement, either the satellite 110 or the satellite 111 is always visible in the zenith direction of 55 degrees or more. Since the satellites 110 and 111 have a period of about 24 hours, they can be seen or not seen in the zenith direction at an elevation angle of 55 degrees or more periodically and regularly. In this case, the satellites 110 and 111 appear alternately in a zenith direction with an elevation angle of 55 degrees or more in a cycle of about 12 hours throughout Japan, and each appears to stay for about 12 hours in a zenith direction with an elevation angle of 55 degrees or more. There is also a time zone when both satellites can be seen simultaneously in the zenith direction with an elevation angle of 55 degrees or more. This is repeated daily with a cycle of about 24 hours.

Therefore, in FIGS. 13 to 16, which show an example of a system using this orbital arrangement, the satellite represented by the artificial satellite 90 is used for satellite communication, so that communication interruption due to shields and obstacles is reduced. A communication system can be constructed.

(4-2) Orbital Arrangement Example 2 This orbital arrangement example is a case in which service is provided for all over Japan.

In this orbital arrangement example, there are four orbital planes as shown in FIG. 12, and each orbital plane has satellites 120a, 120b and 12
0c and the satellite 120d are arranged one by one. The satellite 120a orbits 121a, the satellite 120b orbits 121b, the satellite 120c orbits 121c, and the satellite 120d orbits 121d orbits each in about 12 hours. The orbital periods of the satellites 120a, 120b, 120c and 120d are about 12 hours, and the eccentricity is 0.70
0.80 or less, and the orbit inclination angle is 30 degrees or more and 45 degrees or less or 135 degrees or more and 150 degrees or less,
And the perigee argument is 270 degrees. The ascending intersections of the four satellites are 90 degrees apart, as shown in Figure 12.
The apogee is set to appear at an appropriate position above Japan. As for the positional relationship of each satellite in each orbit, the satellite 120a and the satellite 120c are
When the satellite 120b and the satellite 120d are at perigee on a and 121c, the satellites 120b and 120d are arranged so as to be at apogee on their orbits 121b and 121d.

With this orbital arrangement, the satellite 12 which is represented by the artificial satellite 90 in the zenith direction with an elevation angle of 70 degrees or more in Hokkaido, Honshu, Shikoku and Shishima in Kyushu and Okinawa in Japan.
0a, satellite 120b, satellite 120c, or satellite 120d are always visible. Since the satellites 120a, 120b, 120c and 120d have a period of 12 hours, they are periodically and regularly seen or not seen in the zenith direction with an elevation angle of 70 degrees or more. This orbital arrangement is outlined in Figure 1.
And obtained by the control method shown in FIG. In this case, satellites 120a, 120b, 120c and 120d have elevation angles of 70 in Hokkaido, Honshu, Shikoku, and Kyushu and Okinawa.
Appearing alternately once a day in the direction of the zenith more than degrees,
It looks like staying for about 6 hours each. As a result, any satellite is visible in the zenith direction with an elevation angle of 70 degrees or more for 24 hours a day. There are also time zones in which multiple satellites can be seen simultaneously in the zenith direction with an elevation angle of 70 degrees or more. This is repeated daily with a cycle of about 24 hours.

Therefore, in FIG. 13 to FIG. 16 in which this orbit arrangement is applied to the system, by using a satellite represented by the artificial satellite 90 for satellite communication, communication with less interruption of communication due to obstacles or obstacles is achieved. It becomes possible to build a system.

The above description is for Case 3 in Table 4. For Case 2 in Table 3, the orbital arrangement for shifting the right ascension of the ascending node by 90 degrees in the same manner as described above makes it possible to do exactly the same in offshore Torishima and Minamitorishima. It is possible to make any satellite visible at all times in the zenith direction with an elevation angle of 70 degrees or more throughout Japan except for remote islands on the southern sea such as

(4-3) Orbital Arrangement Example 3 This orbital arrangement example is for the case where a service is provided in a range from about 70 degrees north latitude to about 70 degrees south latitude in the whole world.

In this orbit element example, it is assumed that the orbit and the satellite are properly used according to the latitude of the service target area.
For the area from about 70 degrees north latitude to 30 degrees north latitude, the orbital period is 24 hours, the eccentricity is 0.42 or more and 0.48 or less, and the orbit inclination is 62 or more and 66 degrees or less, or 114 or more and 118 degrees or less, and the perigee argument. 270 degree orbital plane, ascending RA right 60
Six planes are shifted by degrees and two satellites are arranged in each orbit plane. The positional relationship between the two satellites in the same orbit plane is such that one is at perigee and the other is at apogee. north latitude
Twelve geostationary satellites will be deployed in geosynchronous orbits in a geosynchronous orbit, shifted from each other by 30 degrees in the longitude direction, targeting an area from 30 degrees to 30 degrees south latitude. In addition, the service is available from 30 degrees south latitude to about 70 degrees south latitude, the orbital period is about 24 hours, the eccentricity is 0.42 or more and 0.48 or less, and the orbit inclination angle is 62 or more and 66 degrees or less, or 114 or more and 118 degrees or less and perigee Orbital planes with a 90-degree argument are arranged in six planes with the right ascension of the ascending node shifted by 60 degrees, and two satellites are arranged on each orbital plane. The positional relationship between the two satellites in the same orbit plane is such that one is at perigee and the other is at apogee. The six orbital planes covering about 70 degrees north to 30 degrees north latitude and the six orbital planes covering about 70 degrees south latitude to 30 degrees south latitude shall share the same orbital plane. That is, on a certain track surface,
Two satellites with perigee over the southern hemisphere and two satellites with perigee over the northern hemisphere orbit in total, and there are six such orbital planes 60 degrees apart from the earth axis. Will be.

The orbital arrangement is obtained by the algorithm shown in FIG. 1 for the outline, and the orbital elements are shown in Table 4 and is realized by the control method shown in FIG. Due to such orbital plane and satellite arrangement,
In the area from 70 degrees to about 70 degrees south latitude, at least one of the above 36 satellites will be always visible in the zenith direction with an elevation angle of 50 degrees or more. In an area from about 70 degrees latitude to 30 degrees latitude, four or six satellites orbiting adjacent orbital planes appear alternately in the zenith direction, so that a constant communication line can be secured. In the region from latitude 30 degrees north to latitude 30 degrees south, geosynchronous satellites are used, so satellites can always be seen in a fixed direction, and stable communication is possible.

As described above, in FIG. 13 to FIG. 16, which are examples in which this orbit arrangement is applied to the system, by using the satellite represented by the artificial satellite 90 for satellite communication, communication interruption due to shields and obstacles is reduced. A communication system can be constructed.

(4-4) Orbital Element Example 4 This orbital element example is for the case where service is provided for the entire world from about 85 degrees north latitude to about 85 degrees south latitude.

In this orbital element example, orbits and satellites are selectively used according to the latitude of the service target area.
The service period is about 24 hours, the orbital cycle is about 24 hours, the eccentricity is 0.42 or more and 0.48 or less, and the orbit inclination is 62 or more and 66 or less or 114 or more 118
Orbital planes with a perigee of less than 270 degrees and a perigee argument of 270 degrees are arranged on four planes with the ascending ascension shifted by 90 degrees each, and three satellites are arranged on each orbital plane. The positional relationship of the three satellites in the same orbit plane is
The perigee passing time on the orbit is shifted by about 8 hours. Twelve geostationary satellites will be placed in geosynchronous orbits at geosynchronous orbits, shifted from each other by 30 degrees in the longitude direction, targeting the region from 30 degrees north latitude to 30 degrees south latitude. Furthermore, the orbital cycle is about 24 degrees from 30 degrees south latitude to about 85 degrees south latitude.
Time and eccentricity are 0.42 or more and 0.48 or less and orbit inclination is 62
The four orbit planes with degrees not less than 66 degrees or less than 114 degrees and not more than 118 degrees and the perigee argument of 90 degrees are arranged on four planes with the ascending ascension shifted by 90 degrees, and three satellites are arranged on each orbit plane. The positional relationship between the two satellites in the same orbit plane is such that the perigee passing times in orbit are shifted by about 8 hours. The four orbital planes that cover about 85 degrees north to 30 degrees north latitude and the four orbital planes that cover about 85 degrees south latitude to 30 degrees south latitude share the same orbital plane. In other words, a certain orbital plane has a total of six orbiting satellites with perigee over the southern hemisphere and three satellites with perigee over northern hemisphere. There will be four faces apart.

The orbital arrangement is obtained by the algorithm shown in FIG. 1 for the outline, the orbital elements are shown in Table 4, and is realized by the control method shown in FIG. Due to such orbital plane and satellite arrangement,
In the area from 85 degrees to about 85 degrees south latitude, at least one of the 36 satellites will be visible in the zenith direction with an elevation angle of 50 degrees or more. In an area from about 85 degrees latitude to 30 degrees latitude, satellites orbiting adjacent orbital planes appear alternately in the zenith direction, so that a constant communication line can be secured. In the region from latitude 30 degrees north to latitude 30 degrees south, geosynchronous satellites are used, so satellites can always be seen in a fixed direction, and stable communication is possible.

According to the orbital arrangement examples described above, a satellite communication system or an earth observation system in which at least one satellite is always visible in a cone formed by an allowable half apex angle centered on the zenith is used as few satellites as possible. It can be composed of numbers. The required number of artificial satellites can be reduced as compared with a system that performs global communication using other low-to-medium-altitude satellites. The line can be secured. Since the number of satellites is small, the development, launch, and operation costs of satellites can be reduced, so that the costs required for system construction can be reduced. As a result, an inexpensive communication service can be finally provided.

(4-5) Orbital Arrangement Example 5 This orbital arrangement example is for a case where service is provided for all over Japan.

In this orbital arrangement example, there are four orbital planes as shown in FIG. 12, and each orbital plane has satellites 120a, 120b and 12
0c and the satellite 120d are arranged one by one. The satellite 120a orbits 121a, the satellite 120b orbits 121b, the satellite 120c orbits 121c, and the satellite 120d orbits 121d orbits each in about 24 hours. The orbital periods of the satellites 120a, 120b, 120c and 120d are about 24 hours, and the eccentricity is 0.24
In the range of not less than 0.38 or less, and the orbital inclination angle is in the range of 35 to 40 degrees or 140 to 145 degrees,
And the perigee argument is about 270 degrees. The ascending junctions of the four satellites are 90 degrees apart, as shown in Fig. 12, so that the apogee appears at an appropriate position above Japan.

As for the positional relationship between the respective satellites in their respective orbits, when the satellite 120a is at a perigee on its orbit 121a, the satellites 120b and 120d are in their orbits 121b and 121d.
122.5 degrees away from each perigee above, satellite 120
c is arranged so as to be at an apogee on the orbit 121c.

According to such orbit arrangement examples, satellites 120a, 120b, and 120c represented by artificial satellite 90 in the zenith direction with an elevation angle of 70 degrees or more in Hokkaido, Honshu, Shikoku, and Shishima in Kyushu and Okinawa, Japan. Alternatively, the arrangement is such that one of the satellites 120d is always visible. Satellite 120a, Satellite 120b, Satellite 12
Since 0c and the satellite 120d have a cycle of about 24 hours, they can be seen or not seen in the zenith direction with an elevation angle of 70 degrees or more, and they are periodically and regularly removed.

This example of the orbital arrangement is obtained by the outline shown in FIG. 1 by the algorithm, and is realized by the control method shown in FIG. In this case, satellite 120a in Hokkaido, Honshu, Shikoku and Shishima of Kyushu and Okinawa
The satellites 120b, 120c, and 120d appear alternately once a day in the zenith direction with an elevation angle of 70 degrees or more, and appear to stay for about six hours.

Thus, for 24 hours a day, any satellite is visible in the zenith direction with an elevation angle of 70 degrees or more. There are also time zones in which multiple satellites can be seen simultaneously in the zenith direction with an elevation angle of 70 degrees or more. This is repeated daily with a cycle of about 24 hours.

Therefore, in FIG. 13 to FIG. 16 in which this orbital arrangement is applied to a system, by using a satellite typified by the artificial satellite 90 for satellite communication, communication with less interruption of communication due to obstacles or obstacles is achieved. It becomes possible to build a system.

In the above orbit arrangement example 1, one day from all over Japan
An example was shown in which one of the satellites was visible in the zenith direction with an elevation angle of 55 degrees or more for 24 hours. In this orbital arrangement example 5 with four satellites, the elevation angle was 24 hours a day from all over Japan. It is designed so that any satellite can be seen in the zenith direction of 70 degrees or more. Tables 7, 8, and 9 show examples of visibility of satellites from ten cities in one day.

[0102]

[Table 7]

[0103]

[Table 8]

[0104]

[Table 9]

In Tables 7 to 9 above, Ambsat-1 to Ambsat
at-4 is a tentative name given to identify the satellite. When each satellite is seen from each city, the time zone where the elevation angle is more than 70 degrees is indicated by a thin line. The time zone in which the thin line is partially bold is the time zone in which the satellite can be seen above the city at an elevation angle of 80 degrees or more.

According to this arrangement example, in a region from Sendai to Osaka, in a time zone of 80% or more of 24 hours a day,
Any satellite can be made visible in the zenith direction with an elevation angle of 80 degrees or more.

(5) System to which satellites moving in orbit according to the present invention are applied (5-1) System example 1 System example 1 is a satellite communication system covering the whole of Japan, and FIG. An application example as a telephone system is shown.

As shown in FIG. 13, in the present system example, an artificial satellite 90 having subsystems such as an attitude control system, a power supply system, a communication system, and a thermal control system suitable for the above-mentioned elliptical orbit is provided. A terrestrial mobile communication terminal 91 capable of performing satellite communication via an artificial satellite 90, a fixed telephone 92, a fixed telephone network 93, a mobile telephone 95, a mobile telephone network 96, and a gateway communication station 94. Have been.

The terrestrial mobile communication terminal 91 enables communication with the fixed telephone 92 or the mobile telephone 95. One of the input conditions for determining the six elements of the artificial satellite according to the present invention is described. When used within the service target area, the transmission / reception means is determined to be used on the assumption that transmission / reception of a signal to / from the artificial satellite 90 appearing within a predetermined elevation angle range in the zenith direction. For this reason, for example, when using a directional antenna as the transmitting and receiving means of the terrestrial mobile communication terminal 91, it is sufficient to simply point the antenna in the zenith direction regardless of the area, and there is an artificial satellite. There is no need for the user to search for directions (east, west, north and south).

According to the present system example, it is possible to perform communication relating to a mobile object such as a mobile phone or a car phone for the whole world. Since a worldwide communication system can be configured with a small number of satellites, an inexpensive communication service can be provided.

(5-2) System Example 2 System example 2 is a satellite communication system for the whole of Japan, and FIG. 14 shows an example of application as a system mainly for image transmission from a moving body such as an ambulance. Is shown.

In FIG. 14, the system includes an artificial satellite 90 having subsystems such as an attitude control system, a power supply system, a communication system, and a thermal control system suitable for the above-mentioned elliptical orbit, and an ambulance 97
And an emergency lifesaving center 98. ambulance
Image data 99 such as an endoscope, an echo, an electrocardiogram, and a camera relating to an emergency patient being transported at 97 are transmitted to an emergency medical center 98 via an artificial satellite 90, and from the emergency medical center 98,
The appropriate treatment for the patient can be transmitted as 100. Here, the ambulance 97 is taken as an example, but a system similar to this example can be applied to a case where a large amount of data is transmitted from a general mobile body.

According to this system example, since at least one satellite is always visible in a cone formed by an allowable half apex angle centered on the zenith, a shield that obstructs the field of view such as artificial structures, plants, and natural terrain. Even in an area where there is, a communication line can be easily secured for a long time by using this satellite. As a result, image communication from a mobile object such as an ambulance or a sports relay can be almost always performed irrespective of the state of surrounding shields. Furthermore, according to the present system example, by transmitting image data on a patient from an ambulance to an emergency center, a specialist at the emergency center can be notified of an appropriate treatment method. Can be performed. This allows
If appropriate measures can be taken during emergency transport, human lives can be saved for cases that were saved.
In addition, the present invention can be applied to sports broadcast television programs and the like, and high-quality images can be transmitted in real time.

(5-3) System Example 3 System example 3 is a satellite communication system for services throughout Japan. FIG. 15 shows an example of application as a system for rescuing victims in mountains, oceans, etc. I have.

Referring to FIG. 15, the system includes an artificial satellite 90 having subsystems such as an attitude control system, a power supply system, a communication system, and a thermal control system suitable for the above-mentioned elliptical orbit, and an artificial satellite 90 constituting a global positioning system. A satellite 102, a mobile communication terminal 107 having a function of measuring its own position by a positioning signal from the global positioning system and capable of communicating via an artificial satellite 90, and a mountain rescue center 105 for police, fire, etc. It is composed of Victims 101 in the mountains,
By receiving the positioning signal 103 from the artificial satellite 102 constituting the global positioning system, the mobile communication terminal 107 measures its own position, and the data 104 such as its own position, its own ID, and the number of their own are obtained. Police /
It is transmitted to the mountain rescue center 105 such as fire department. The mountain rescue center starts rescue work promptly based on the data 104. At this time, if the rescue helicopter 106 or the like can be used, the rescue operation can be quickly performed by transmitting the previous data 104. Although the example of mountain distress has been shown here, it can be applied to marine distress.

According to the present system example, victims in mountainous areas or in the ocean can communicate their positions via satellites regardless of the surrounding natural topography. At present, when searching for mountain victims, several helicopters are flown or rescue teams from the mountain society actually walk around the mountains to search for and rescue the victims, but as in this system example Knowing the location of the victim prior to rescue, minimizing rescue operations,
Rescue can be performed promptly.

(5-4) System Example 4 System example 4 is a satellite communication system for services throughout Japan. FIG. 16 shows an example of application to an automatic utility billing system.

As shown in FIG. 16, in this system example, an artificial satellite 90 having subsystems such as an attitude control system, a power supply system, a communication system, and a thermal control system suitable for the above-mentioned elliptical orbit.
, A utility billing center 108, a fixed communication terminal 109 capable of communicating via an artificial satellite 90, and terminals 109a and 109 for measuring various usages such as electricity, gas, water and sewage.
b, 109c and 109d. Fixed communication terminal 109
And a terminal 109a that measures the amount of electricity, gas, water, etc. used,
109b, 109c and 109d are provided in each home, apartment house, building, building, and the usage in each is measured, and the measured usage is periodically sent to the utility billing center 108 via the satellite 90. Transmitted. As a result, it is possible to efficiently measure electricity, gas, water, and the like, which are currently performed by visiting each house from door to door, and collectively execute a billing process for a utility bill.

In this system example, by using the orbiting satellite according to the present invention, a satellite communication line can be easily secured even with antenna equipment installed in a house surrounded by a high-rise building. If this is applied, utilities such as electricity, gas, and water, whose usage is currently tabulated on a door-to-door basis, can also be tabulated via satellite, greatly reducing the labor costs required for tabulating usage. . This reduction in labor costs can be expected to further reduce utility charges.

In the above system examples 1 to 4, only one artificial satellite 90 is shown in FIGS. 13 to 16, but it represents a plurality of satellites. Similarly, the artificial satellite 102 is representative of the Navstar satellite constituting the United States Global Positioning System (GPS), the Russian GLONASS satellite for navigation, the Japanese multipurpose satellite for transportation, and the like.

(5-5) System Example 5 FIG. 17 shows a system example of a satellite communication mobile station mounted on the ambulance 97 shown in FIG.

This system can be used for normal moving images or high-quality still images or high-quality still images via a stable transmission path that is secured by using the high-elevation angle satellite according to the present invention and is not affected by the movement of the ambulance 97. This is for transmitting moving images and other data detected regarding the condition of the patient, and for receiving treatment instructions and the like from the emergency lifesaving center 98 serving as a base station.

More specifically, the present system includes a transmitting / receiving antenna 201, a power amplifier 202, a frequency converter 203, and a modulator 20 as means for transmitting / receiving data via a satellite.
4. A camera 205, a microphone 206, an image compression encoding device 207, a communication telephone 208, a low noise amplifier 212, a frequency converter 213, and a demodulator 214 are provided.

Further, the present system is used for a moving ambulance 9
As means for controlling the attitude of the transmitting / receiving antenna 201 mounted on the antenna 7, a beacon receiver 217 and an antenna controller 2
16, motor driver 215, elevation angle motor 209, polarization angle motor 21
0, and an azimuth motor 211.

Further, the present system includes an accelerometer 224, a gyro 225, a GPS antenna 218, a VICS antenna 220, and auxiliary data for optimizing means for controlling the attitude of the transmitting / receiving antenna. G
A PS receiver 219, a VICS receiver 221, and an image display device 222 are provided.

In the present system example, the rescuer on board the ambulance can talk with a doctor working at the rescue center 98 via the artificial satellite 90 via the contact telephone 208. The communication telephone 208 and information such as images and sounds obtained by the camera 205 and the microphone 206 about the condition of the patient being transported are compressed and encoded by the image compression encoding device 207, and then the modulator 204 , Is frequency-converted by the frequency converter 203, is power-amplified by the power amplifier 202, and is transmitted to the artificial satellite 90 via the transmission / reception antenna 201.

The above information received by the artificial satellite 90 is transmitted from the artificial satellite 90 to the emergency rescue center 98. At the emergency rescue center 98, a doctor or the like looks at data on the patient, and transmits an appropriate treatment instruction to the ambulance 97 via the artificial satellite 90.

Information about this instruction is received by the transmitting / receiving antenna 201 provided in the ambulance 97, amplified by the low noise amplifier 212, frequency-converted by the frequency converter 213, and demodulated by the demodulator 214. Is transmitted to the contact telephone 208, and the rescuer on board the ambulance 97 can receive a treatment instruction from a doctor at the emergency rescue center 98.

The strength of the signal received by the transmission / reception antenna 201 is adjusted so that the beacon signal separated by the frequency converter 213 is received by the beacon receiver and the strength of the beacon signal is optimized. Is optimized by driving the elevation angle motor 209, the polarization angle motor 210, and the azimuth angle motor 211 in response to the signal from the antenna controller 216, and changing the direction of the transmission / reception antenna 201.

In changing the direction of the antenna, the GPS antenna 218 and the GPS receiver 219 are used to receive positioning signals from GPS satellites constituting the global positioning system. good. Further, by detecting the change in the moving direction of the ambulance using the accelerometer 224 and the gyro 225, the auxiliary data of the attitude control operation of the antenna is supplied, so that the antenna attitude with higher adaptability can be obtained. A configuration for realizing control may be adopted.

When selecting a travel route for an ambulance, use the GPS
The receiver 219 and GPS antenna may be assisted.
Information from the VICS antenna 220 and the VICS receiver 221 may be helpful.

(5-6) System Example 6 This system example 6 is a satellite communication system for the service of, for example, the whole of Japan. FIG. 18 shows an example of application to a system for providing programs to a plurality of mobile units. ing.

As shown in FIG. 18, in this system example, an artificial satellite 232 having subsystems such as an attitude control system, a power supply system, a communication system, and a thermal control system suitable for the above-mentioned elliptical orbit.
, A satellite communication earth station 231 for providing programs to a plurality of mobiles, and an artificial satellite 233 constituting a global positioning system.
And mobile units 235 of public transportation such as taxis and railway vehicles, general mobile units 236 such as private cars, and a transmitting station 234 for transmitting VICS information. Here, the mobile devices 235 and 236 are equipped with communication devices shown in FIG. 19 described later.

The mobile bodies 235 and 236 are equipped with a GPS antenna 256 and a GPS receiver 257, respectively. The mobile bodies 235 and 236 receive positioning signals from the artificial satellite 233 constituting the global positioning system, and receive their own position and attitude. And a function of measuring the speed and the like, and the measured information is sent to the transmitting / receiving terminal 244.
In addition, the mobile units 235 and 236 include a receiving antenna 257 and a VICS receiver 259 for receiving a signal from the VICS information transmitting station 234, and have a function of receiving traffic congestion information and the like. Similarly, it is sent to the transmitting / receiving terminal 244.
The transmission / reception terminal 244 has a function of receiving an operation instruction input by a user of the system to select desired information from information that can be selected, and acquiring the selected information.

Information obtained by the above GPS receiver 258,
The information obtained by the VICS receiver 259 and the selected desired information are subjected to signal processing on the transmission / reception terminal 244, then modulated by the modulator 243, and frequency-converted by the frequency converter 242,
After the power is amplified by the power amplifier 241, the transmitting and receiving antenna 240
Is transmitted to the artificial satellite 232 via

This signal is transmitted through the artificial satellite 232 to the satellite earth station 231 of the program provider. In the satellite communication earth station 231, based on the information transmitted from the mobile units 235 and 236, the location where the mobile unit is moving, time zone, select a program according to the wish, etc., via the artificial satellite 232, Moving object 235
And 236 to distribute the program.

The types of programs distributed in the present invention are:
There is no particular limitation. According to the present invention, since the artificial satellite 232 can always be positioned at a high elevation angle, it is possible to secure a constantly stable and continuous transmission path via the artificial satellite 232 regardless of the moving state of the moving object. Can be. Therefore, it is possible to receive not only moving images but also still images and text broadcasts. Note that a signal processing method, a frame memory, and the like are provided as appropriate depending on the type of information to be received.

As specific programs to be distributed, for example,
Department stores belonging to the area where the moving object is moving, supermarket time service information, museum / museum exhibition information, cinema performance information, criminal / wanderer information,
Internet information and the like.

[0139] The mobile units 235 and 236 receive the information transmitted from the satellite earth station 231 of the program provider via the artificial satellite 232 by the transmission / reception antenna 240 provided in the mobile units. The received signal is amplified by a low-noise amplifier 248, frequency-converted by a frequency converter 249, and demodulated by a demodulator 247, after which video information is displayed on an image display 245 and audio information is obtained by a speaker 246. .

The signal demodulated by the demodulator 247 includes program information that can be selected in the area where the moving object is moving, and this information is displayed as video or audio on the image display 245 or the speaker 246. At the same time as confirmation, it is also sent to the new sending / receiving terminal 244.

The strength of the signal received by the transmitting / receiving antenna 240 is determined so that the beacon signal separated by the frequency converter 249 is received by the beacon receiver and the strength of the beacon signal is optimized. Is optimized by driving the elevation angle motor 253, the polarization angle motor 254, and the azimuth angle motor 255 in response to the signal from the antenna controller 251 and changing the direction of the transmission / reception antenna 240.

According to the present system example, information corresponding to a location in an urban area can be transmitted to a mobile unit more reliably. That is, a television mounted on a mobile unit that receives a TV signal transmitted from a ground station or a geostationary satellite in a conventional manner can enjoy television broadcasts while the mobile unit is moving under the influence of buildings and trees. Have difficulty. However, on the transmission path in the present system, a television broadcast signal is sent from the zenith direction. For this reason, it is hard to be affected by buildings and trees, and a stable broadcast can be enjoyed.

Further, according to the present system example, in a department store or a supermarket, information such as a time service can be appropriately transmitted to a moving body moving in a nearby area, so that an increase in the effect of attracting customers is expected. You can do it.

Further, by sending a photograph or features of a criminal or a wandering person to a moving object, an effect of expediting the discovery of a criminal or a wandering person can be expected.

[0145] The system examples 1 to 6 described above use the elliptical orbit satellite according to the present invention when the elevation area of the satellite is high when the satellite is viewed from the service area. However, the present invention is not limited to this. For example, if the elevation angle when viewing the satellite from the service target area is low, the following uses are possible.

That is, according to the orbital position of the elliptical orbit satellite, when the elevation angle is low when viewed from the service area, the communication between the service area and the area other than the service area is relayed. If the elevation angle is further reduced, it is possible to relay communication between areas other than the service target area.

(6) Example of Orbit Control System for Artificial Satellite The orbit of the above-mentioned satellite is controlled as follows.

The orbital six elements 17 (orbital major radius 11, perigee argument 12, eccentricity) obtained in FIG.
13, orbit inclination 14, ascending right ascension 15 and right angle separation 16)
Is input to the launch vehicle tracking control equipment 21 as an input target trajectory element as shown in FIG. This information is transmitted from the launch vehicle tracking and control equipment 21 to the launch vehicle 23 to put the satellite 20 into the target orbital element. If the launch vehicle 23 equipped with the satellite 20 is likely to deviate from the target orbit during the launch stage, the launch vehicle 23 may automatically correct the trajectory, or the launch vehicle tracking control equipment 21 The command may be transmitted to the launcher 23 to guide the launcher 23.

Even after reaching the target orbital element 22 by the launch vehicle 23 in this way, the orbital element is perturbed by the influence of the gravitational field of the earth, the gravity of the sun and the moon, the solar wind, etc., and has a short period with time. And the orbital element constantly changes in a long cycle. In this case, the satellite 20 needs orbit control.

As shown in FIG. 3, generally, the orbital six elements 31 of the orbit that the satellite 20 is currently flying are transmitted by the transmission / reception system 24 of the satellite tracking control equipment 18 to the telemetry and ranging signals 27 transmitted by the satellite 20. After receiving and extracting the ranging signal 28, the signal is transmitted to the ranging system 25, and the orbit determination program 30 in the computer system 26 calculates and determines the distance and the rate of change of distance 29 measured here as final inputs. Is done. By comparing the obtained six orbital elements 31 with the six orbital elements 17 suitable for the target service target area, the orbit control program 32 in the computer system 26 is obtained.
Calculates the required attitude control amount and trajectory control amount 33. This determines which thruster of the propulsion system of the satellite should be fired, when and for how long. This is converted into a control command 35 by a command generation program 34 in the computer system 26 and transmitted to the satellite 20 via the transmission / reception system 24 of the satellite tracking control equipment 18.

As shown in FIG. 4, the control command transmitted to the artificial satellite 20 is received by the communication system 37 mounted on the artificial satellite 20, and then the transmitted command is decoded in the data processing system 38. From the decoded command, the information 41 of the attitude control amount and the orbit control amount is appropriately processed in the satellite mounted attitude and orbit control system 39, and if necessary, the attitude control actuator 42
By changing the attitude by driving the satellite, and further by firing the thruster of the artificial satellite onboard propulsion system 40 as commanded, the artificial satellite 20 finally shows the six orbital elements 17 suitable for the service target area Into orbit and controlled.
In addition, the satellite 20 constitutes a global positioning system.
(Global Positioning System) or a GLONASS receiver, the satellite 20 itself stores the six orbital elements 17 suitable for the service area in advance, and uses this to autonomously orbit the satellite. It may be configured to perform control.

As described above, the track element 17 suitable for the service area determined by the algorithm shown in FIG.
Is controlled and realized.

[0153]

According to the present invention, the orbit of an artificial satellite required to be visible in the zenith direction for a long period of time, a method for setting six orbital elements that define the orbit, and various methods for using satellites on the orbit System can be provided.

Further, according to the present invention, it is possible to provide an orbit control system for realizing orbit control of an artificial satellite based on the set six orbit elements.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a method for setting six orbital elements in which a satellite is visible for a long time in a zenith direction according to the present invention.

FIG. 2 is an explanatory diagram showing a flow of information for controlling an orbit of an artificial satellite to six orbital elements set by an algorithm of the present invention.

FIG. 3 is an explanatory diagram showing operations and information flows performed in the satellite tracking control equipment for orbit control of the satellite.

FIG. 4 is an explanatory diagram showing processing and information flow performed inside the artificial satellite for orbit control of the artificial satellite.

FIG. 5 is an explanatory diagram of six orbital elements that define the shape of the orbit, and is a view of the orbit viewed from the normal direction of the orbital plane.

FIG. 6 is an explanatory diagram of six orbital elements that define the shape of the orbit, and is a view of the orbit and the earth as a bird.

FIG. 7 is a diagram illustrating that it is necessary to set six orbital elements in consideration of a service target area, and is a view of the earth as a bird.

FIG. 8 shows a trajectory with a period of about 24 hours, an eccentricity of 0.25, an orbit inclination of 55 degrees, and a perigee argument of 270 degrees.
FIG. 4 is an explanatory diagram showing the ground trajectory of the orbit on a world map. The world map shows angles at equal intervals in a latitude direction and a longitude direction.

FIG. 9 shows a trajectory with a period of about 24 hours, an eccentricity of 0.38, a trajectory inclination angle of 45 degrees, and a perigee argument of 270 degrees.
FIG. 4 is an explanatory diagram showing the ground trajectory of the orbit on a world map. The world map shows angles at equal intervals in a latitude direction and a longitude direction.

FIG. 10 is an explanatory diagram showing a world map at equal intervals in the latitude and longitude directions. On this map, an approximately 24 hour period, an eccentricity of 0.35, an orbit inclination angle of 63.4 degrees, and a perigee argument are shown. For a 270-degree trajectory, the ground trajectory 82 of the trajectory and the trajectory that has the same orbital period, eccentricity, orbit inclination, and perigee argument as the trajectory that gives the ground trajectory 82 can be obtained so as to overlap the ground trajectory 82. Shows the ground track 83 of the orbit where the ascending intersection RA is set.

FIG. 11 is an explanatory view of the orbit arrangement example 1 obtained by the algorithm of the present invention, in which the orbit is looked down around the earth.

FIG. 12 is an explanatory view of the orbit arrangement example 2 obtained by the algorithm of the present invention, in which the orbit is looked down around the earth.

FIG. 13 is an explanatory diagram showing an application example as a mobile telephone system.

FIG. 14 is an explanatory diagram showing an application example as a system centering on image transmission from a moving body such as an ambulance.

FIG. 15 is an explanatory diagram showing an application example as a system for rescuing victims in mountains, the sea, and the like.

FIG. 16 is an explanatory diagram showing an example of application to an automatic utility billing system.

FIG. 17 is an explanatory diagram showing another example of application as a system centering on image transmission from an ambulance.

FIG. 18 is an explanatory diagram showing an example of application to a system that distributes a program to a plurality of mobile objects.

19 is an explanatory diagram illustrating a configuration example of a communication system in a mobile body in the system example of FIG. 18;

[Explanation of symbols]

1. 1. Setting the half apex angle (work process) 2. Setting required service time (work process) 3. Setting of polygons encompassing the service target area (work process) 4. Setting the major radius of the track (work process) 5. Setting the perigee argument (work process) 6. Setting the number of satellites and the ascending ascension of each satellite and the near-angle separation (work process) 7. Setting the initial value of the orbit inclination angle (work process) 8. Change the eccentricity and calculate the visible time from the polygon vertices (work process) 10. Change the inclination of the orbit and calculate the visible time from the polygon vertices (work process). 10. Setting the right ascension of right ascension and right angle separation (work process) Orbit major radius (output information) 12. Perigee argument (output information) 13. Eccentricity range (visual information) from the vertices of each polygon is almost equal (output information) 14. The range of the orbit inclination angle at which the visible time from each polygon vertex is almost equal (output information) Ascending intersection RA (output information) 17. Near-point separation (output information) Six orbital elements suitable for the service target area (input information to each tracking control facility) 50. Ellipse focus 51. Artificial satellite 52. The apogee of the ellipse (if the focus of the ellipse is the earth, the apogee) 53. Periphery of the ellipse (perigee if the focus of the ellipse is the earth) Orbital long radius 55. Orbit short radius 56. Apogee radius Perigee radius 58. Proximity separation 60. Earth 61. Equatorial plane of the earth 62. Ascending intersection 63. Perigee argument 64. Orbit inclination 65. Perigee 66. Apogee 70. The westernmost point of the service area 71. The easternmost point of the service area 72. The northernmost point of the service area 73. The southernmost point of the service area 74. Meridian passing through the westernmost end 75. Meridian passing through the easternmost end 76. Latitude line passing through the northernmost end 77. Latitude line passing through the southernmost point 78. Equator 79. Earth axis 80. 81. Trajectory of the orbit with a period of about 24 hours, an eccentricity of 0.25, an orbit inclination of 55 degrees, and a perigee argument of 270 degrees 82. Ground trajectory of the orbit for a trajectory with a period of about 24 hours, an eccentricity of 0.38, an orbit inclination of 45 degrees, and a perigee argument of 270 degrees 83. Ground trajectory of the orbit for a trajectory with a period of about 24 hours, an eccentricity of 0.35, an orbit inclination of 63.4 degrees and a perigee argument of 270 degrees. The same orbital period and eccentricity as the orbit that gives the ground track 82,
90. Ground trajectory of the trajectory with orbit inclination and perigee argument, with the ascending RA set to obtain a ground trajectory that overlaps the ground trajectory 82. 91. An artificial satellite having subsystems such as an attitude control system, a power supply system, a communication system, and a thermal control system suitable for the elliptical orbit of the present invention. 92. Terrestrial mobile communication terminal that can perform satellite communication via artificial satellite 90 Fixed telephone terminal 93. Fixed telephone network 94. Gateway communication station 95. Mobile phone terminals 96. Mobile telephone network 97. Ambulance 98. Emergency and Critical Care Center 99. Endoscope, echo, electrocardiogram, camera, etc. image data of emergency patients 100. Instructions for treatment from the critical care center 101. Victims 102. Satellites that make up the Global Positioning System 103. Positioning signal 104. Data of victim ID, number of victims, location of distress, etc. 105. Mountain rescue centers such as police and fire departments 106. Rescue helicopter 107. A terrestrial mobile terminal 108 having a function of receiving a positioning signal 103 from the artificial satellite 102 and locating its own position and the like and capable of communicating via the artificial satellite 90 108. Utility billing center 109. Ground fixed communication terminal 109a. Electricity usage measurement terminal 109b. Gas usage measurement terminal 109c. Water and sewage consumption measurement terminal 109d. Other utility bill measurement terminals 110. Artificial satellite 111. Artificial satellite 112. Orbit of satellite 110 113. Orbit of artificial satellite 112 114. Equatorial plane of the earth 116. Ascending intersection of orbit 112 117. Ascending intersections 120a, 120b, 120c, 120d of orbit 113. Artificial satellites 121a, 121b, 121c, 121d. Satellites 120a, 120b, 120c,
120d orbits 122a, 122b, 122c, 122d. Orbits 121a, 121b, 121c, 121d
Ascending intersection.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeki Nakamura 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Space Technology Promotion Headquarters, Hitachi, Ltd. # 1 Inside Hitachi, Ltd.Hitachi Plant (72) Inventor Masataka Owada 3-1-1 Sachimachi, Hitachi, Hitachi, Ibaraki Prefecture Inside Hitachi, Ltd.Hitachi Plant (72) Inventor Masahiko Ikeda, Hitachi City, Ibaraki 3-1-1, Machi, Hitachi, Ltd.Hitachi Plant (72) Inventor Takashi Yabutani 4-6, Kanda Surugadai, Chiyoda-ku, Tokyo Inside Hitachi Research Institute, Ltd. (72) Inventor Masahiro Ito Chiyoda-ku, Tokyo 4-6 Kanda Surugadai Inside Hitachi Research Institute, Ltd.

Claims (22)

[Claims] 1. A plurality of elliptical orbits such that an apogee is on a specific service target area are set so that the right ascension of the ascending intersection is at a predetermined angle, and the satellite orbits on each elliptical orbit.
The use of a satellite group arranged on the elliptical orbit so that at least one satellite equipped with a communication system is always visible within a predetermined elevation angle range in the zenith direction as viewed from the service target area. Communication system characterized by the following. 2. A plurality of elliptical orbits such that an apogee is located on a specific service target area. The orbit planes are set at a predetermined angle to each other, a satellite orbits on each elliptical orbit, and viewed from the service target area. And a satellite group arranged on the elliptical orbit so that at least one satellite equipped with any communication system is always visible within a predetermined elevation range in the zenith direction. Communications system. 3. A plurality of elliptical orbits such that the apogee is on a specific service target area are set such that the ascending intersection right ascension has a predetermined angle, and the satellite orbits on each elliptical orbit.
At least one artificial satellite equipped with a communication system is arranged in the elliptical orbit so that at least one satellite equipped with a communication system is always visible within a predetermined elevation angle range in the zenith direction viewed from the service target area, and the ascending intersection right ascension is at a predetermined angle. And an artificial satellite group obtained by combining the inclination angle and the eccentricity of the elliptical orbit so that the visible time from the ground is almost equal to each other and obtained in the width of each numerical value range. Communications system. 4. A plurality of elliptical orbits such that the apogee is on a specific service target area, the orbit planes thereof are set at a predetermined angle to each other, a satellite orbits each elliptical orbit, and viewed from the service target area. At least one artificial satellite equipped with any communication system within a predetermined elevation angle range in the zenith direction is arranged on the elliptical orbit so that at least one of the satellites is always visible, the ascending intersection RA becomes a predetermined angle, and A communication system using a group of artificial satellites obtained by combining the inclination angle and the eccentricity of the elliptical orbit so that the visible time from the ground is substantially equal to each other and in the range of each numerical value range. 5. An apogee is located on a specific service target area, and a plurality of elliptical orbits whose ground trajectories are substantially the same are set, and orbit around an elliptical orbit with a period of 12 hours or 24 hours. The satellites are arranged one in each orbit, and the ascending intersection of each orbit is separated by an angle obtained by dividing 360 degrees by the number of satellites, and the maximum elevation angle when viewing the geostationary satellite from the service area. At least one satellite equipped with a communication system at a higher angular position is placed in an elliptical orbit so that it is always visible, and when one satellite is at perigee in that orbit, the other satellites are true. A communication system using artificial satellite details in which the near point departure angle is separated by an angle corresponding to a time obtained by dividing the period by the number of satellites. 6. The group of artificial satellites is obtained by combining the elliptical inclination angles and the eccentricity of any of a plurality of elliptical orbits so that the visible time from the ground is substantially equal, and is obtained in the width of each numerical value range. The communication system according to claim 5, wherein the communication system is a communication system. 7. The service target area is set based on the latitude and longitude of the four northernmost, southernmost, westernmost, and easternmost points of the service target area, or a part of the service target area is defined by the four points. If not included in a quadrangle having two points as vertices, it is an area set from latitude and longitude other than the four points of a polygon that includes all the service target areas, 6. Or the communication system according to 6. 8. The communication system according to claim 5, wherein the service target area is the whole of Japan. 9. The communication system according to claim 5, wherein the service target area is in a range from about 70 degrees north latitude to about 70 degrees south latitude in the whole world. 10. The communication system according to claim 5, wherein the service target area is in a range from about 85 degrees north latitude to about 85 degrees south latitude in the whole world. 11. The satellite according to claim 5, wherein three or four satellites are arranged.
The communication system according to any one of claims 9 and 10. 12. The satellites are orbited on a plurality of elliptical orbits such that the right ascensions of the ascending intersections are set to a predetermined angle and the apogee is on a specific service target area. A communication method, wherein communication is performed using a group of artificial satellites on the elliptical orbit that are always visible within a predetermined elevation angle range in the zenith direction. 13. A satellite orbiting a plurality of elliptical orbits whose orbital planes are set at a predetermined angle to each other and whose apogee is on a specific service target area, and the zenith is viewed from the service target area. A communication method characterized by performing communication using a group of artificial satellites in an elliptical orbit in which at least one of them is always visible within a predetermined elevation angle range of a direction. 14. A plurality of elliptical orbits such that the apogee is on a specific service target area are set such that the ascending intersection right ascension is at a predetermined angle, and a satellite orbits on each of the elliptical orbits. At least one artificial satellite equipped with a communication system within a predetermined elevation range in the zenith direction as viewed from the area.
The inclination angle and the eccentricity of the elliptical orbit are set such that the ascending intersection RA is at a predetermined angle and the visible time from the ground is almost the same. A communication method characterized in that communication is performed using a group of artificial satellites that are combined and obtained in a range of respective numerical values. 15. A plurality of elliptical orbits such that the apogee is on a specific service target area, the orbit planes thereof are set at a predetermined angle to each other, and the satellite orbits on each of the elliptical orbits.
At least one artificial satellite provided with any communication system within a predetermined elevation angle range in the zenith direction as viewed from the service target area is arranged on the elliptical orbit so that at least one satellite is always visible,
A group of artificial satellites obtained by combining the inclination angle and the eccentricity of the elliptical orbit so that the ascending intersection RA becomes a predetermined angle, and the visible time from the ground is almost equal, and the width of each numerical range is obtained. A communication method characterized in that communication is performed by using a communication method. 16. A plurality of elliptical orbits in which the apogee is on a specific service area and the orbits of the orbits substantially coincide with each other are set, and orbit around the elliptical orbit with a period of 12 hours or 24 hours. The satellites are arranged one in each orbit, and the ascending intersection of each orbit is separated by an angle obtained by dividing 360 degrees by the number of satellites, and the maximum elevation angle when viewing the geostationary satellite from the service area. At least one satellite equipped with the communication system at a higher angle position is arranged in an elliptical orbit so that at least one satellite is always visible, and when one satellite is in perigee in that orbit, the other satellites A communication method characterized in that communication is performed by using a group of artificial satellites arranged at an angle corresponding to a time obtained by dividing the period by the number of satellites at a near-peripheral angle. 17. The group of artificial satellites is obtained by combining the elliptical inclination angles and the eccentricity of any of a plurality of elliptical orbits so that the visible time from the ground is substantially equal, and is obtained in the width of each numerical value range. The communication method according to claim 16, wherein the communication method is a communication method. 18. The service target area is set based on the latitude and longitude of the four northernmost, southernmost, westernmost, and easternmost points of the service target area, or a part of the service target area is defined by the four points. If not included in a quadrangle having two points as vertices, the entire area to be serviced is an area set from latitude and longitude other than the four points of the polygon included in the polygon, Or the communication method according to 17. 19. The communication method according to claim 16, wherein the service target area is the whole of Japan. 20. The communication method according to claim 16, wherein the service target area is in a range from about 70 degrees north latitude to about 70 degrees south latitude in the whole world. 21. The communication method according to claim 16, wherein the service target area is in a range from about 85 degrees north latitude to about 85 degrees south latitude in the whole world. 22. The satellite according to claim 16, wherein three or four satellites are arranged.
22. The communication method according to any one of 19 and 21.