JPH0389727A - Communication satellite - Google Patents

Abstract

PURPOSE:To attain inexpensive communication through the use of one satellite moving round the earth by providing a reception part receiving a transmission signal designating a transfer destination earth station from an earth station, an accumulation part storing received information and a transmission part transmitting stored information from the sky above the transfer destination earth station. CONSTITUTION:The satellite 1 moving round the earth consists of the reception part 2 receiving a transmission wave from an earth station on the earth and demodulating transmission data, the accumulation part 3 which temporarily stores transmission data, the transmission part 4 transmitting accumulated data to the designated earth station from the sky over a designated position and a control part 5 controlling the reception part 2, the accumulation part 3 and the transmission part 4 in accordance with request information on data transmission and reception of the earth station. Thus, simultaneous informations are eliminated compared to a geostationary communication satellite, and bidirectional information permitting transmission delay time can inexpensively be transmitted by temporarily accumulating reception information and transmitting it from the sky over the designated point.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to communication satellites, and is particularly useful when performing two-way communication between two distant points on the earth using an earth-orbiting artificial satellite. This invention relates to a communication satellite having a data communication storage function.

[Conventional technology]

Normally, the majority of communication satellites are geostationary communication satellites that utilize geostationary orbits located 36,000 km above the equator. Geostationary satellites relay radio waves received from each point on the earth's surface to other points on the earth's surface that can be seen from the satellite.
- Information can be transmitted to a large number of points at once using only radio wave propagation delay time differences, and bidirectional communication information can be exchanged in real time. Furthermore, conventionally, earth-orbiting satellites such as resource exploration satellites and scientific satellites have mostly performed one-way data communication in which data acquired by the satellite is transmitted to the ground.

[Problem to be solved by the invention]

However, many of the communications handled by the conventional geostationary communication satellites mentioned above do not require broadcasting or bidirectionality, and it is difficult to use geostationary communication satellites, which are expensive to launch, for such communications. has an uneconomical problem. Furthermore, in order to provide communication services to the entire earth using geostationary communication satellites, at least three satellites are required.

An object of the present invention is to provide a communication satellite that uses one earth-orbiting artificial satellite, is suitable for communication that does not require broadcasting of data communication, can tolerate delays in data transmission, and is extremely inexpensive. It's about doing.

[Means to solve the problem]

In the communication satellite of the present invention, the communication satellite body orbits in a polar orbit at a low altitude or a medium altitude, and the communication satellite body receives a transmission signal specifying a transfer destination earth station from an earth station at a certain point on the earth. a receiving unit; a storage unit that stores received information;
It has a transmitting section that transmits the stored information in the air above the destination earth station, and a control section that inputs the control information demodulated by the receiving section and controls the storage section and the transmitting section.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

Figure 1 is an embodiment of the present invention. Figure 2 is a schematic diagram illustrating data exchange between the ground and the satellite in this embodiment. Figures 3 and 4 are operations of the earth-orbiting satellite in this embodiment. FIG. In FIG. 1, an earth-orbiting satellite 1 includes a receiving section 2 that receives transmitted waves from any earth station on the ground and demodulates the transmitted data, a storage section 3 that temporarily stores this transmitted data,
A transmitter 4 transmits the accumulated data to a predetermined earth station in space at a predetermined location; The control section 5 is configured to perform control according to data transmission/reception request information.

Next, the operation between the ground and the satellite in FIG. 2 will be explained.

Earth-orbiting satellite 1 is located above earth station 8 (point A) with receiver 1
The transmitted wave is received by the storage unit 6, and the data information is stored in the storage unit 6. A destination is assigned to the received data signal, and this information is also transmitted to the control unit 4. Information on the amount of flight of the earth-orbiting satellite 1 in the orbit 6 is stored in the storage unit 3. When the satellite 1 reaches the sky above the destination earth station 9, which is the zero point of the orbit 6, the storage unit 3
The information is read out and transmitted to the earth station 9 by the transmitter 4.

FIG. 3 shows the ground trajectory 6A of the earth-orbiting satellite of this embodiment. This ground trajectory 6A shows a case where the satellite has an altitude of 909 km and an orbital inclination of 99 degrees, and the horizontal and vertical scales in the figure indicate the longitude and latitude, respectively. If the trajectory shown in the figure is taken, it will be possible to communicate with earth-orbiting satellites from all over the world at least twice, once during the day and once at night. It is therefore possible to transmit the received information anywhere in the world within 12 hours.

Next, a case will be explained in which the orbit in this embodiment is a sun-synchronous all-daylight orbit, which is special among polar orbits. FIG. 4 shows the relationship between the annual movement of the earth and the orbit 6 of this embodiment. In this orbit 6, the direction of the sun is almost perpendicular to the orbit plane throughout the year, and the satellite can always receive sunlight without entering the earth's shadow (eclipse) 10. Therefore, there is no need for storage batteries for supplying power during eclipses, heaters for preventing temperature drops, etc., and the equipment for earth-orbiting satellites can be made simple and inexpensive. In addition, in this orbit, the times when the ground station and the satellite communicate are at sunset and sunrise at each location, which has the advantage of being able to transmit information that matches the rhythm of human activity.

〔Effect of the invention〕

As explained above, the present invention orbits in a polar orbit, temporarily accumulates received information, and transmits it over a designated point, thereby eliminating the need for repeatability and allowing transmission delay time compared to geostationary communication satellites. This has the effect of allowing interactive information to be transmitted at an extremely low cost.

In addition, by launching an earth-orbiting satellite into a sun-synchronous, all-daylight orbit where there is no eclipse even in polar orbits, the power supply and thermal control systems inside the satellite are extremely simple, thereby providing an economical communication satellite. be able to.

[Brief Description of the Drawings] Figure 1 is a block diagram of an embodiment of the present invention, Figure 2 is a schematic diagram showing the operation of this embodiment, and Figures 3 and 4 are the satellite and earth of this embodiment. It is an explanatory diagram explaining a relative locus with. DESCRIPTION OF SYMBOLS 1... Earth-orbiting satellite, 2... Receiving unit, 3... Storage unit, 5... Control unit, 6... Orbit, 6A... Ground trajectory, 7... Earth, 8゜9...Earth station, O...Earth's shadow.

Claims (1)

[Claims] 1. A communication satellite body orbits in a low-altitude or medium-altitude polar orbit, and a transmission signal specifying a transfer destination earth station from an earth station at a certain point on the earth is transmitted within the communication satellite body. a receiving section that receives the information; a storage section that stores the received information; a transmitting section that transmits the stored information above the destination earth station; and a receiving section that receives the control information demodulated by the receiving section and stores the information A communication satellite comprising: a controller; and a controller that controls the transmitter. 2. The communication satellite according to claim 1, wherein the polar orbit is a sun-synchronous all-daylight orbit.