JP2965067B2 - Communication satellite and multiple access satellite communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a communication satellite,
In particular, it relates to a small communication satellite that realizes communication between small earth stations.

[0002]

2. Description of the Related Art A conventional communication satellite, as shown in FIG.
A plurality of (or large) antennas 41 forming a plurality of beams, a plurality of radio repeaters 42, and a plurality of diplexers 43 are provided. The antenna 41, the radio repeater 42, and the diplexer 43 are each treated as a pair, and two antennas and two relays are used so that two antennas and two repeaters realize bidirectional communication. The container is connected to two diplexers 43. Therefore, this communication satellite requires the number of lines to be set × 2 antennas, repeaters, and diplexers. In the example of FIG. 4, four lines can be realized.

As shown in FIG. 5, another conventional communication satellite includes a plurality of antennas 51, a waveform shaping section 52a and an amplifying section 52b constituting a plurality of radio wave repeaters, and a diplexer for connecting these. 53, and an exchange 54 connected between the waveform shaping section 52a and the amplifying section 52b. In this communication satellite, the output side of the repeater (particularly, the waveform shaping section 52b) can be connected to any antenna by the exchange 54. Therefore, this communication satellite can realize more lines with fewer antennas, repeaters, and diplexers than the above-mentioned conventional communication satellite. For example, in the example of FIG. 5, six lines (six lines in time division, two simultaneous lines) can be realized.

[0004]

A conventional communication satellite having the number of antennas and repeaters required for setting a line requires a large number (or large) of antennas and a large number of repeaters. There is a problem that it must be made large.

Further, a communication satellite having an exchange has a problem that it must be expensive because an exchange having a complicated configuration is used.

Further, in order to keep the beam direction of the antenna constant, all communication satellites require an attitude control mechanism such as a flywheel for maintaining the attitude of the communication satellite, so that miniaturization is difficult. There is a problem.

An object of the present invention is to provide a communication satellite which is small and has a simple configuration.

[0008]

According to the present invention, in a communication satellite equipped with a plurality of antennas and radio wave relay means, the plurality of antennas are arranged on an outer peripheral surface parallel to a rotation axis of the communication satellite. And a communication satellite provided with an antenna switching means for selectively connecting an antenna heading toward the earth from the plurality of antennas to the radio wave relay means in synchronization with the rotation of the communication satellite. Can be

Here, it is preferable that the plurality of antennas have coverages different from each other.

[0010] More specifically, the communication satellite according to the present invention has a plurality of receiving antennas and a plurality of transmitting antennas as the plurality of antennas, and one radio repeater as the radio relay means. Wherein the antenna switching means selectively connects one of the receiving antennas to an input side of the radio wave repeater, and selectively connects one of the transmission antennas to the radio wave repeater. Connected to the output side of
It has a pair of antenna switches.

[0011] Alternatively, the radio wave relay means includes a pair of radio wave repeaters, and the plurality of antennas includes a plurality of antennas forming a first group and a plurality of antennas forming a second group, A first antenna switch for selecting one of the plurality of antennas forming the first group as the antenna switching means, and selecting one of a plurality of antennas forming the second group; And a first diplexer is provided between one input side and the other output side of the pair of radio relays and the first antenna switch, A second antenna switch is provided between one output side and the other input side of the pair of radio repeaters and the second antenna switch.
Is provided so that each of the plurality of antennas can be used for both transmission and reception.

According to the present invention, in a multiple access satellite communication system for communicating between a plurality of ground stations via a communication satellite, a plurality of antennas are provided as the communication satellite, the antennas being parallel to the rotation axis of the communication satellite. A communication satellite provided on the outer peripheral surface and provided with antenna switching means for selectively connecting an antenna heading toward the earth from the plurality of antennas to the radio wave relay means in synchronization with the rotation of the communication satellite is used. ,
The multiple access satellite communication system is characterized in that the radio relay means is used in a time division manner in synchronization with the rotation of the communication satellite.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. FIG.
The satellite communication system shown in FIG.
1a, 11b, 11c, and 11d, and a spin satellite (communication satellite) 12 orbiting in a low orbit. Here, the small earth station refers to an earth station provided with transmission / reception equipment having lower output power and lower antenna gain than conventional earth station equipment such as VSAT. The spin satellite is an artificial satellite that rotates around the spin axis 13 as a center of rotation in order to stabilize its attitude. The communication between the small earth station and the spin satellite is assumed to use a microwave band, a millimeter wave band, light, or the like. In addition, small earth stations use Pure ALOHA or Slotted ALOHA transmission control and automatic retransmission by ARQ (Automatic ReQUEST) to avoid errors due to packet collision or loss due to simultaneous transmission. Error-free communication.

The spin satellite 12 has a spin axis 13 which is an axis of rotation. Then, the outer peripheral surface parallel to the spin axis rotates so as to face the earth. A plurality of antennas 14a to 19a and 14b to 19b (partially invisible) are arranged on the outer peripheral surface of the spin satellite 12 parallel to the spin axis 13. Here, the spin satellites are hexagonal prisms and two are arranged on each of the six outer peripheral surfaces. However, the present invention is not limited to this, and the satellites may have a cylindrical shape, for example, May be more or less. Each antenna has a different coverage corresponding to the line to be set. However, since the coverage of each antenna depends on the line to be set, that is, the position of the small earth station, each of the antennas is not necessarily completely independent, and there may be an antenna having the same coverage. .

As shown in FIG. 1B, the spin satellite 12 has antenna switches 20a and 20b to which a plurality of antennas 14a to 19a and 14b to 19b are respectively connected.
And diplexers 21a and 21b connected to the antenna switches 20a and 20b, respectively, and a pair of radio repeaters 22 connected to the diplexers 21a and 21b.
a, 22b.

The antenna switches 20a and 20b are synchronized with the spin of the spin satellite 12 based on a spin detection signal or the like from an attitude control device including a not-shown earth sensor and the like.
Select an antenna for each. Here, the antennas selected by the antenna switches 20a and 20b are antennas that direct beams toward the earth. The antennas selected by the antenna switches 20a and 20b are transmitted to the radio repeaters 22a and 22a via the diplexers 21a and 21b.
22b, and enables radio wave relay with coverage of each antenna as a service area.

The diplexers 21a and 21b are used for transmitting and receiving antennas in common.
A signal received by one of the pair of antennas selected by a and 20b is input to one of the radio repeaters 22a and 22b, and the output is supplied to the other antenna. The signal received by the other antenna is transmitted to the radio wave repeaters 22a and 22a.
2b and input to one antenna.

The radio repeaters 22a and 22b are of a type called a so-called vent pipe. The radio repeaters 22a and 22b amplify the input signal with low noise, convert the frequency, further amplify the power, and output the amplified signal.

Hereinafter, the operation of the satellite communication system will be described.

The spin satellite 12 detects its own spin by an attitude control device including an earth sensor and the like. The antenna switches 20a and 20b select one of the antennas in synchronization with the detected spin.

For example, the antenna selection by the antenna switches 20a and 20b is performed by selecting the antennas on the same outer peripheral surface of the spin satellite 12, such as the antennas 14a and 14b, the antennas 15a and 15b,. Then, the antennas 14a, 15a,.
19a and antennas 14a, 15a,.
Radio wave relay with the coverage of 19b as a service area becomes possible. Since the coverage of the antenna provided on the same outer peripheral surface is set to be separated in the direction of the spin axis 13, communication between two small earth stations located on the earth and separated in the direction of the spin axis 13 is performed. Can be realized.

Since the coverage of each beam is different from each other, the service area changes when the antenna is switched. Therefore, as described above, when antenna switching is performed so as to select an antenna on the same outer peripheral surface, communication between two sets of six small earth stations can be performed in a time sharing manner.

The spin satellite 12 is a small earth station 11.
The beacon signal is transmitted to control the transmission / reception timing of a, 11b, 11c, and 11d. This beacon signal includes switching timing information indicating switching timing of the antenna switches 20a and 20b. Small Earth Station 11
Each of a, 11b, 11c, and 11d receives a beacon signal and performs transmission and reception based on switching timing information included in the beacon signal, thereby realizing communication with a desired partner station. It should be noted that transmission / reception to / from a specific partner station in each small earth station 11 is performed while the spin satellite 12 performs one spin.
Since only six periods can be performed, digitized information is converted into small-capacity packets.

As described above, in the satellite communication system according to the present embodiment, communication can be performed between the two small earth stations located apart from each other along the direction of the spin axis 13 of the spin satellite 12. Antenna switch 2 of satellite 12
By controlling the switching timing of 0a and 20b as shown in FIG. 2, communication between two small earth stations located apart from each other in a direction orthogonal to the spin axis 13 can also be realized.

That is, the antenna switch 2 of the spin satellite 12
When the switching timing of 0a and 20b is controlled as shown in FIG. 2, not only the case where the antenna on the same outer peripheral surface is selected but also the case where the antennas on two adjacent outer peripheral surfaces are selected one by one. Exists. Thus, the adjacent two
When the antennas on the two outer peripheral surfaces are selected, the spin axis 13
Communication between two small earth stations located in a direction perpendicular to the direction of the earth. Therefore, in this case, the spin axis 13
6 sets of two small earth stations separated in the direction perpendicular to the spin axis 13 and 6 sets of two small earth stations separated in the direction orthogonal to the spin axis 13.
Communication between a pair of two stations becomes possible. However, the time during which transmission and reception can be performed in the communication between the two stations is 1/12 of the spin cycle of the spin satellite 12.

As is apparent from the above description, in the satellite communication system of the present embodiment, by adjusting the coverage (directional direction) of each antenna and the switching timing of the antenna, the small earth station 11a, 11b, 11
Any of c and 11d can execute communication with a desired partner station in a time sharing manner.

In the above description, a case has been described in which a pair of radio repeaters are used to realize two-way communication. However, if one-way communication is sufficient, the configuration may be as shown in FIG.

[0029]

According to the present invention, a plurality of antennas are provided on the outer peripheral surface parallel to the spin axis of the spin satellite, and the antennas are selectively connected to the repeater in synchronization with the spin, thereby achieving a small size. Thus, a communication satellite that can set a relatively large number of lines can be obtained with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention,
(A) is a conceptual diagram of a satellite communication system including a communication satellite of the present invention, and (b) is a diagram showing a configuration of the communication satellite of the present invention.

FIG. 2 is a time chart showing an example of antenna switching timing in the communication satellite of FIG. 1;

FIG. 3 is a diagram showing another configuration of the communication satellite of the present invention.

FIG. 4 is a diagram showing a configuration of a conventional communication satellite.

FIG. 5 is a diagram showing a configuration of another conventional communication satellite.

[Explanation of symbols]

 11a, 11b, 11c, 11d Small Earth Station 12 Spin Satellite (Communication Satellite) 13 Spin Axis 14a-19a Antenna 14b-19b Antenna 20a, 20b Antenna Switch 21a, 21b Diplexer 22a, 22b Radio Repeater 41 Antenna 42 Radio Repeater 43 Diplexer 51 Antenna 52a Waveform shaping unit 52b Amplifying unit 53 Diplexer 54 Switch

Claims (5)

(57) [Claims] 1. A communication satellite equipped with a plurality of antennas and a radio wave relay means, wherein the plurality of antennas are arranged on an outer peripheral surface parallel to a rotation axis of the communication satellite, and
A communication satellite comprising an antenna switching means for selectively connecting an antenna heading toward the earth from among the plurality of antennas to the radio wave relay means in synchronization with the rotation of the communication satellite. 2. The communication satellite according to claim 1, wherein said plurality of antennas have different coverages. 3. The apparatus according to claim 2, further comprising: a plurality of receiving antennas and a plurality of transmitting antennas as the plurality of antennas; a single radio repeater as the radio relay means; A pair of antennas for selectively connecting one of the transmission antennas to an input side of the radio repeater and selectively connecting one of the transmission antennas to an output side of the radio repeater. 3. The communication satellite according to claim 1, further comprising a communication device. 4. A plurality of antennas forming a first group and a plurality of antennas forming a second group as the plurality of antennas, the pair of antennas having a pair of radio wave repeaters as the radio wave relay means, One of a plurality of antennas constituting the first group as the antenna switching means
A first antenna switch for selecting one of the plurality of antennas, and a second antenna switch for selecting one of a plurality of antennas forming the second group, and the pair of radio repeaters is provided. A first diplexer is provided between one input side, the other output side, and the first antenna switch, and one output side, the other input side, and the second input side of the pair of radio wave repeaters are provided. 3. The communication satellite according to claim 1, wherein a second diplexer is provided between the antenna switch and the antenna switch so that the plurality of antennas can be used for both transmission and reception. 5. In a multiple access satellite communication system for performing communication between a plurality of ground stations via a communication satellite, a plurality of antennas are arranged on an outer peripheral surface parallel to a rotation axis of the communication satellite as the communication satellite. A communication satellite provided with antenna switching means for selectively connecting an antenna toward the earth from the plurality of antennas to the radio wave relay means in synchronization with the rotation of the communication satellite; The multiple access satellite communication system, wherein the radio relay means is used in a time division manner in synchronization with the satellite communication system.