JPH0482329A - Satellite communication system - Google Patents

Abstract

PURPOSE:To prevent blocking by a building or the like at a high altitude area and to eliminate the need for tracking of a satellite feeder link station with a large antenna diameter by combining a circulating satellite and a still satellite and utilizing the inter-satellite communication. CONSTITUTION:A feeder link station A radiates a transmission radio wave to a still satellite 12. The still satellite 12 applies frequency conversion and amplification to the received radio wave and the resulting radio wave radiates to a circulation satellite 13 for inter-satellite communication. The circulation satellite 13 applies frequency conversion and amplification to the received radio wave and sends the resulting radio wave to a specific area (in this case, a high altitude area in which a user station B is in existence). The feeder link station A uses a large aperture antenna because the transmission rate is high, and since the station A sends a radio wave to the still satellite 12, the station A is formed to be a stationary station. Since the transmission rate of the inter- satellite communication between the still satellite 12 and the circulation satellite 13 is comparatively low and the transmission rate of the communication between the circulation satellite 13 and the user station B is also low, a small sized antenna is employed for them respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Field of Industrial Application) The present invention relates to a satellite communication system that performs communication using, for example, an artificial satellite.

(Prior Art) Conventionally, in a satellite communication system, communication has been performed via a communication satellite placed in a geostationary orbit. For example, in a telephone communications network, radio waves are emitted from a transmitting station to a geostationary satellite, where the satellite performs frequency conversion and amplification, and then re-radiates them toward a destination area on Earth. Communicating with the receiving station. According to this method, since the satellite is stationary, there is no need to track the antenna, so it has become the mainstream of satellite communications.

However, in high latitude regions such as Europe, the angle of elevation of the satellite is small, so communications are often hindered by blocking objects such as buildings. In order to solve this problem, countries such as Europe and the Soviet Union are considering a method of providing communication services to high latitude areas by using orbiting satellites with orbital inclinations so that they fly over high latitude areas, and some of them have been implemented. ing.

However, in order to communicate with orbiting satellites, satellite tracking by the antenna is essential. For this reason, this does not pose much of a problem for receiving stations that have relatively low transmission rates and require small antennas, but for transmitting stations (feeder link stations) that have high transmission rates and have to increase the antenna diameter. It is difficult to track orbiting satellites.

(Problem to be solved by the invention) As stated above, in conventional satellite communication systems, when communicating using geostationary satellites, the elevation angle of the satellite becomes low in high latitude areas, causing problems due to blocking by buildings, etc. In communications, feeder link stations with large antenna diameters must track orbiting satellites.

This invention was made to solve the above problems, and is a satellite communication system that can prevent pro-soaking of buildings even in high latitude areas, and that feeder link stations with large antenna diameters do not require satellite tracking. The purpose is to provide

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a satellite communication system according to the present invention includes a communication line between a feeder link station and a geostationary satellite,
It is configured to include a communication line between a communication station in a specific area and an orbiting satellite, and a communication line between the geostationary satellite and the orbiting satellite.

(Function) In the satellite communication system with the above configuration, by combining an orbiting satellite and a geostationary satellite and using their inter-satellite communication, the antenna of the feeder link station can be can be immobilized.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a conceptual diagram thereof, in which numeral 11 is the earth, 12 is a geostationary satellite that is stationary with respect to the rotation of the earth 11, and 13 is an orbiting satellite whose orbit has an inclination angle with respect to the rotation of the earth 11.

It is assumed that there is a feeder link station A and a user station (including a mobile station) B on the earth 11, and the user station B is located at a relatively high latitude. In addition, in Fig. 1, 14 is a geostationary orbit, and 15 is a geostationary orbit.
is the orbit.

The feeder link station A emits transmission radio waves toward the geostationary satellite 12. The geostationary satellite 12 performs frequency conversion and amplification of the received radio wave and radiates it toward the orbiting satellite 13, thereby performing inter-satellite communication. The orbiting satellite 13 converts and amplifies the frequency of the received radio waves and radiates them to a specific area (here, the high latitude area where user station B is located).

To explain the specific configuration of FIG. 1 with reference to FIG. 2, feeder link station A has a high transmission rate and uses a large-diameter antenna, but since it emits radio waves toward the geostationary satellite 12, it can be fixed. . Since the inter-satellite communication between the geostationary satellite 12 and the orbiting satellite 13 has a relatively low transmission rate, small antennas can be used for each other. Since the transmission rate between the orbiting satellite 13 and the user station B is also low, small antennas can be used for each other.

However, user station B needs to track the orbiting satellite 13 with its antenna.

In general, it is advantageous for a large number of user stations B to communicate from the orbiting orbit 15, especially in high latitude areas, in order to prevent blocking by buildings, etc. According to the above configuration, the communication from the geostationary orbit 14 has a higher elevation angle. realizable. at the same time,
The feeder link station A is generally connected to a terrestrial communication network and is not directly related to users, so there is no problem in communicating with the geostationary satellite 12, and the antenna can be fixed, which can reduce costs. .

Here, since the viewing period of the orbiting satellite 13 is limited, it is effective to use a plurality of them. In this case, since each orbiting satellite can be accessed via a feeder link line with the geostationary satellite 12, it can be accessed from one point on the geostationary orbit 14, making effective use of geostationary orbit positions, which have become valuable in recent years. Can be done.

In addition, in a system using only an orbiting satellite, a drive type antenna for tracking the satellite is essential, and it may be difficult to implement large-capacity data communication. This can be easily achieved by connecting with a link line.

Therefore, in the satellite communication system with the above configuration, by combining the orbiting satellite 13 and the geostationary satellite 12 and using their inter-satellite communication, the feeder link station can take advantage of the advantages of high-elevation communication using the orbiting satellite 13. By fixing the antenna of A, the cost of the entire system can be reduced and the geostationary orbit can be effectively utilized.

Note that the orbit 15 may be a circular orbit with the center of rotation around the center of the earth 11, but an elliptical orbit is more effective. For example, the time spent in the sky above the target area can be extended, and user station B can easily track the satellite. Furthermore, by widening the antenna beam angle, there is no need for satellite tracking, which can reduce costs.

Furthermore, by providing a feeder link station and a user station for this feeder link station in the northern and southern hemispheres, respectively, when the orbiting satellite is in the northern hemisphere, it is possible to communicate between the feeder link station and the user station in the northern hemisphere. Also, when the orbiting satellite is in the southern hemisphere, communication can be performed between the feeder link station and the user station in the southern hemisphere. That is, the utilization efficiency of the orbiting satellite can be increased, and it is even more effective if the orbit of the orbiting satellite is made into a circular orbit with the center of rotation around the earth.

[Effects of the Invention] As described above, according to this invention, it is possible to apply it to high latitude areas! ,)
However, it is possible to prevent blocking by buildings, etc., and feeder link stations with large antenna diameters can provide a satellite communication system that does not require satellite tracking.

[Brief explanation of drawings]

FIG. 1 is a system conceptual diagram showing an embodiment of a satellite communication system according to the present invention, and FIG. 2 is a configuration diagram showing a specific configuration of the embodiment. 11...Earth, 12...Geostationary satellite, 13...Orbiting satellite, A...Feeder link station, B...User station. 1st rXJ

Claims (4)

[Claims] (1) A satellite communication system comprising a communication line between a feeder link station and a geostationary satellite, a communication line between a communication station in a specific area and an orbiting satellite, and a communication line between the geostationary satellite and the orbiting satellite. (2) The satellite communication system according to claim 1, wherein the antenna of the feeder link station is fixed. (3) The satellite according to claim 1, wherein the satellite has a plurality of orbiting satellites that communicate with the communication station in the specific area, and at least one orbiting satellite always exists within the field of view of the communication station. Communications system. (4) A communication line between a feeder link station and a geostationary satellite, a communication line between a communication station in a specific area and an orbiting satellite, and a communication line between the geostationary satellite and the orbiting satellite, A satellite communication system characterized in that communication stations are provided in the northern hemisphere and in the southern hemisphere, respectively, and the orbit of the orbiting satellite is a circular orbit centered around the center of the earth.