JPH0472000A - Geostationary optical fiber tether satellite system - Google Patents

Abstract

PURPOSE:To simply perform inter satellite relay in which centering around a satellite on a geostationary satellite orbit a plurality of satellite are arranged on both sides of a straight line connecting this satellite to the center of the earth by connecting between the satellites with an optical fiber tether line. CONSTITUTION:An optical fiber tether line 30 is constituted so that a plurality of optical fiber 20 of about 125 m diameter are embedded in a 'kevler' fiber (or aramid fiber) of about one mm diameter, and high speed signal can be transmitted in the optical fiber tether line 30. A plurality of satellites 32 - 34 are connected to each other with such optical fiber tether line 30, the satellite 32 in the center is arranged on the geostationary satellite orbit to be stationary, and a geostationary satellite system is constituted. By transmitting information in the optical fiber tether line 30, inter satellite relay can be performed.

Description

[Detailed Description of the Invention] [Summary] Regarding the geostationary optical fiber tether satellite system, an optical fiber line is embedded in a tether line that constitutes a geostationary tethered satellite, for example, Kevlar, to enable information transmission. ■ Geostationary tethered satellite Inter-satellite relay that constitutes the With one satellite at the center, multiple satellites are placed on both sides of a straight line connecting the satellite and the center of the earth, and the system is constructed from thin polymer material wires with excellent strength and contains multiple optical fiber wires inside. The satellites are linked together using optical fiber tether lines that enable communication, and due to the gravitational gradient caused by the difference in gravity between the multiple satellites from the earth, they are always stably oriented toward the center of the earth, and the overall rotational speed is approximately the same as the earth's rotation speed. It consists of a geostationary satellite system that rotates at the same speed.

[Industrial Application Field] The present invention is applicable to geostationary satellite orbits.
A new satellite method (geostationary optical fiber tether satellite) in which optical fiber is embedded in the tether line of a geostationary tether satellite, in which multiple satellites are chained in a tether on both sides of one satellite on the GSO (GSO). This is related to the method.

[Conventional technology]

In recent years, geostationary satellite orbit (GSO), which is a finite natural resource, has become increasingly crowded, and it is necessary to make effective use of it and increase the number of satellites that can be launched.

For the effective use of orbit, the International Radiocommunications Consultative Committee (CC
It has been studied by the Fixed Satellite Service Research Group (SG-4) of JR) and is described in CCJRRep, 453-4. This includes improving antenna siderope characteristics (e.g. using offset, Cassegrain, antennas).
, use of polarization, use of spot beam satellite antennas,
Efforts have been made to improve the effective orbit utilization rate by relaxing interference tolerance values, interference compensation, and optimal satellite placement that takes into account the regional distribution of service areas (1). This improvement rate is often 2 to 3 times that of each technology, and newer technology is required.

Geostationary Tet
Her 5atellite (GTS)'' expands the use of geostationary satellite orbits from one line to two-dimensional use, making it possible to improve the effective orbit utilization rate by 10 to 20 times.

FIG. 4 is a diagram explaining a geostationary tether satellite (GTS). In the figure, 1 represents a geostationary satellite orbit (GSO), 2 to 4 represent satellites, 5 represents a thin line, and 6 represents the earth.

As shown in Fig. 4, a geostationary tethered satellite has a satellite 2 on a geostationary satellite orbit 1 as its center, and a plurality of satellites 3.4 are placed on a line between this point and the center of the earth 6, with a diameter of 1mm
Connect with a thin wire 5 made of Keb Ier material as shown below. At this time, different gravity is applied to each satellite due to the gravitational force of the earth 6, and a gravitational gradient occurs. As a result, this satellite group 2, 3.
4 rotates stably around the Earth, and if its period matches the rotation of the Earth, it appears stationary. When viewed from the earth station, if the satellites have a certain separation angle, the same frequency band can be used for each satellite, and the effective use of orbits times the number of satellites can be achieved.

When calculating the communication capacity using the parameters of each frequency using the characteristics of the hardware realized with current technology, compared to the conventional system using only the geostationary satellite orbit 11,
As shown in Figure 7, in the 6/4 GHz band, the
/1iGHz band: 8 to 14 times, 30/20G
In the Hz band, communication capacity can be increased by 10 to 18 times.

References (1) First appearance, Murotani, “Influence of regional distribution of service areas on effective utilization of geostationary satellite orbits”, Journal of the Institute of Electronics and Communication Engineers, Vol. 62-B, No. 6+pp, 519
-526.1979-06 (2) First published, “Problems related to geostationary satellite orbits and various measures for their effective use”, Hokkaido Institute of Technology Research Bulletin,
No. 16, pp, 291-304+ 1988-03
[Problem to be solved by the invention] As mentioned above, geostationary tethered satellites have a great effect on increasing the number of satellites that can be launched into geosynchronous orbits and increasing the communication capacity within the system. Although they are only connected by line 5, information must be transmitted from a dedicated earth station on the ground for each satellite. Therefore, it is natural that the number of earth stations is equal to the number of satellites.

Furthermore, the satellites constituting the geostationary tethered satellite must be spaced apart enough to satisfy the required C/I for the sidelobe break of the earth station antenna. For this reason, in the conventional method where the interference path is complicated, the distance between the satellites becomes large, and the tether line 5 forming the geostationary tethered satellite becomes long. This means that
Weight, authenticity.

This is considered to be disadvantageous in terms of price, etc.

The present invention was created in view of this point, and enables information transmission by embedding an optical fiber line in a tether line that makes up a geostationary tethered satellite, such as Kepler. ■ Simplification and economicalization of the control system by transmitting satellite monitoring and control signals, ■ Distance control of tethered satellites by measuring the elongation of tether lines, etc., and realization of sensors.

[Means to solve the problem]

Therefore, the geostationary optical fiber tether satellite system of the present invention places a plurality of satellites on both sides of a straight line connecting the satellite and the center of the earth, centering on one satellite in a geostationary satellite orbit. A communicable optical fiber tether made of strong, thin polymer material wire containing multiple optical fiber lines is connected between the satellites, and due to the difference in gravity from the earth between the multiple satellites, Due to the resulting gravitational inclination, the satellite is always stably oriented toward the center of the Earth, and the system as a whole forms a geostationary satellite system that rotates at approximately the same speed as the Earth's rotation speed.

Further, in the present invention, the plurality of satellites illuminate different service areas, and the optical fiber tether line performs inter-satellite relay among the plurality of satellites, so that the regional The arrangement order of the plurality of satellites is determined by focusing on the distribution.

Furthermore, in the present invention, the transmission of supervisory control signals from the earth to all satellites or the transmission of supervisory control signals from all satellites to the earth is carried out between a predetermined satellite and an earth station accessing the satellite. The monitoring and control signals from the earth station are transmitted from this satellite to the remaining satellites via the optical fiber tether line, and each satellite separates the monitoring and control signals addressed to itself.
Control is being performed as instructed by the supervisory control signal.

Furthermore, in the present invention, a digital signal for measuring the inter-satellite distance is transmitted through a part of the optical fiber line in the optical fiber tether line, and when the distance between two satellites changes, the inter-satellite distance measurement is performed. The amount of distance change is measured by measuring the phase change of the digital signal.

[Effect]

In the present invention, since the satellites are linked by optical fiber tether lines, relaying between the satellites making up the geostationary optical fiber tether satellite can be easily performed.

Furthermore, in the present invention, each of the plurality of satellites illuminates a different service area, and the relay between the plurality of satellites is performed using an optical fiber tether line. Since the arrangement order is determined, the total length of the optical fiber tether line can be shortened.

Furthermore, in the present invention, data is transmitted between a specific satellite (for example, the satellite closest to the earth) and an earth station located within the service area of the specific satellite, and data is transmitted from the earth station to the satellite. Data to be sent is sent via a specific satellite, and data to be sent from the satellite to the earth station is sent via a specific satellite, so all satellite attitude control, speed control, satellite monitoring telemetry signals, The number of satellite monitoring and control earth stations for transmitting other signals can be reduced, and monitoring and control signal transmitting and receiving devices in multiple satellites can be omitted.

Furthermore, in the present invention, a digital signal for measuring the inter-satellite distance is transmitted through the optical fiber line in the optical fiber tether line, and the amount of change in the distance between the satellites is calculated based on the phase change of the digital signal for measuring the inter-satellite distance. Since it measures distance, it is possible to omit the installation of other distance measuring equipment.

〔Example〕

FIG. 1 is a diagram showing an example of the optical fiber tether line of the present invention. In the figure, 10 indicates Kevlar (or aramid fiber), 20 indicates an optical fiber line, and 30 indicates an optical fiber tether line.

The optical fiber tether line 30 used in the geostationary optical fiber tether satellite (P-GTS) is as shown in FIG.
It is constructed by embedding a plurality of optical fiber lines 20 with a diameter of about 125 μm in Kevlar (or aramid fiber) with a diameter of about 1 mm.

High-speed signals can be transmitted through the optical fiber tether line 30.

FIG. 2 is a diagram showing an example of the geostationary optical fiber tether satellite system of the present invention. In the figure, l is the geostationary satellite orbit, 6
is the earth, 32 to 34 are satellites, and 35 and 36 are satellite intervals, respectively.

As shown in FIG.
A geostationary satellite system is constructed by placing the satellite on a geostationary satellite orbit l and making it stationary. This provides a geostationary fiber optic tether satellite system.

The spacing between the satellites at this time, 35.36, depends on: ■ Frequency used ■ Dimensions of the earth station antenna ■ Side lobe characteristics of the earth station antenna ■ Allowable amount of interference in the required satellite system ■ Modulation/demodulation method ■ Whether the service areas are the same or different It is determined by whether or not there are any.

If the satellite spacing 35.36 is short, the weight of the satellite will be reduced and the launch cost will be reduced. Direction and speed control between each satellite becomes easier. For the same tether length, the number of satellites that can be connected can be increased. Improves reliability.

You can get advantages such as:

By being able to transmit information through the optical fiber tether line 30, inter-satellite relay becomes possible. This makes it possible to shorten the satellite spacing 35.36, which will be explained below.

FIG. 5 is a diagram illustrating a single beam satellite communication system and a multibeam satellite communication system. In the figure, 40 is a single-beam satellite communication system, 41 is a multi-beam satellite communication system, 42 is a beam, 43 is a single-beam satellite,
Reference numeral 44 indicates a service area, 45 indicates a plurality of beams, and 46 indicates a satellite switch.

FIG. 5 explains a single beam satellite communication system 40 and a multibeam satellite communication system 41. In conventional satellite communications, Japan's C8-2 and C53 (Sakura 2 and 3)
Most of the satellites were single-beam satellites 43 with a single beam 42, as shown in FIG. However, in order to further increase the capacity and construct an economical satellite system, it is effective to adopt the multi-beam satellite communication system 41.

The multi-beam satellite communication system 41 uses multiple beams (multi-beams) 4 to cover a service area 44 such as Japan or the United States.
A satellite switch 46 is mounted on the satellite to switch between the beams and perform large-capacity transmission. One satellite's beam illuminates all of the service areas 44; conversely, one earth station is required within a service area to access one satellite. When there are multiple satellites, there are as many earth stations as there are satellites in one service area.

FIG. 6 is a diagram illustrating a conventional multi-beam satellite communication system using a geostationary tether satellite (GTS).

In the figure, 1 is the geostationary satellite orbit, 6 is the earth, 51 to 58 are eight service areas, and 61 to 68 are eight service areas.
69 indicates the total satellite spacing.

It is believed that by applying the multi-beam satellite system described above to a geostationary tethered satellite, large-capacity transmission can be performed efficiently. Figure 6 shows an example of this, with eight satellites 61-6 illuminating eight service areas 51-58.
8 is shown as being chained with a tether line. Since each satellite 61-68 illuminates eight service areas 51-58, the interference route becomes complex and the total satellite spacing 69 increases. The reason for this is that the tether wire is only Kevlar and cannot transmit information.

FIG. 3 is a diagram illustrating a multi-beam satellite communication system according to the present invention. In the figure, ■ is the geostationary satellite orbit, 6 is the earth, 51 to 58 are eight service areas, and 71
77 to 77 are optical fiber tether lines, 81 to 88 are eight satellites, 89 is the total distance between satellites, and 90 is a control signal.

In the geosynchronous tethered satellite of FIG. 3, fiber optic tether lines 71 to 77 according to the present invention are used to
8 are connected. This is the conventional method of inter-satellite relay (Inter 5atellite Link).
:l5L) by using optical fibers for inter-satellite communications without using radio waves (23GHz, 60GHz, etc.) or laser beams.
This is realized using tether wires 71 to 77.

In the embodiment of FIG. 3, one satellite exclusively illuminates one service area, and information between each service area is transmitted via optical fiber tethers 71-77.

As a result, the interference route is greatly simplified and the service
By using an algorithm (Iris) that determines the satellite arrangement order taking into consideration the geographical distribution of areas 51 to 58, it is possible to reduce the total satellite spacing of 89.

Compared to the multi-beam satellite system shown in FIG. 6, the tether line length can be reduced to about 1/3.

Also, satellite 61 in the case of the geostationary tethered satellite in Figure 6
To control the positions of 68 to 68 satellites, it is necessary to provide antennas for each satellite, send control signals simultaneously, and control them individually. This is because signals cannot be transmitted through the tether wire.

On the other hand, in an embodiment of the invention using fiber optic tethers 71-77 as shown in FIG. If the control signal is transmitted to the satellite 88, it becomes possible to transmit the control signal from the satellite 88 to all remaining satellites 81 to 87 through the optical fiber tether lines 71 to 77. The control signal is, for example, a control signal for attitude control or a control signal for position control of a satellite. Observation data obtained by each satellite and data indicating the status of each satellite can also be sent to the earth station via the satellite 88.

As a result, there will be only one satellite monitoring and control station (two even considering backup).
(locations) and contributes to the economicalization of the system.

In addition, a digital signal for measuring the distance between satellites is passed through one or more optical fibers in the optical fiber tether line 30 shown in FIG. When the amount of change increases or decreases, it is possible to know the amount of change by measuring the change in the phase of the digital signal. This makes it possible to perform extremely accurate measurements, and the measurement system can be constructed from electronic components, making it compact and reliable.

This is advantageous in terms of weight reduction.

〔Effect of the invention〕

As is clear from the above description, the geostationary optical fiber tether satellite system of the present invention has the following effects compared to the conventional geostationary tether satellite system that does not use optical fibers.

(a) When linking tethered satellites, it becomes possible to transmit information to the optical fiber tether line and add an intersatellite relay function. This allows each satellite to illuminate a different service area, and by determining the order and arranging the tethered satellites in consideration of the regional distribution of the service area, interference conditions between satellites can be alleviated and the spacing between satellites can be reduced. You can. This allows the tether line length to be shortened, making it possible to improve the weight, reliability, cost, etc. of the tether system.

(b) If the inter-satellite relay function is added using the above-mentioned optical fiber tether line, earth stations within the service area only need to access a specific dedicated satellite, which does not use the optical fiber tether line. Compared to the method of chaining multi-beam satellites that illuminate multiple service areas using a geostationary tethered satellite system, it is necessary to install as many earth stations as there are satellites in each service area. Significant system economy is possible in the system.

(C) In a geostationary tethered satellite system, the position of each satellite.

It is necessary to adjust the speed from the satellite monitoring and control station. If optical fiber tethers were not used, each satellite would need to be monitored and controlled individually, which would require the installation of antennas, transmitting and receiving equipment, etc. on the ground. By using an optical fiber tether line, control signals can be transmitted between satellites via the optical fiber tether line, and it is only necessary to transmit the control signal to one satellite, so the number of earth stations can be reduced. In addition, it is only necessary to send a control signal to the satellite closest to the tethered satellite, so the free space loss is small, and the antenna diameter and transmission output of the earth station can be small, making the system economical. Furthermore, since the amount of delay is small, quick control is possible in emergency situations.

(d) A digital signal is transmitted in an optical fiber tether line, and when the length changes, the value of expansion and contraction can be determined by detecting the phase change of the digital signal. By using this information as a signal necessary for satellite position control, there is no need to newly install a large tether tension detection device, and the geostationary tether satellite system can be made more economical.

(e) Although optical fiber tether lines are being considered for application to geostationary tether satellite systems, they can of course also be used for information transmission on the ground. For example, the optical fiber tether can be used when connecting a large earth station of a base station and a number of small earth stations using a satellite, and distributing data from this small earth station to each subscriber (household). It is. Trunk fiber optic cables require copper wire for bias power feeding and are included in the cable in order to operate the semiconductor components of the repeater, but the distances for the above subscriber lines are somewhat short, and each home Since commercial power is supplied, there is no need for a bias power supply copper wire. By using an optical fiber tether line in such a component-type terrestrial optical transmission line, economicalization can be achieved, and the cost per subscriber can be reduced.

In addition, it can be used as an information transmission line in aircraft, ships, cars, buildings, etc., and is effective because it is extremely thin and lightweight and is not affected by electromagnetic induction.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the optical fiber tether wire of the present invention,
FIG. 2 is a diagram explaining the geostationary optical fiber tether satellite system of the present invention, FIG. 3 is a diagram explaining the multi-beam satellite communication system according to the present invention, FIG. 4 is a diagram explaining the geostationary tether satellite, and FIG. Figure 5 is a diagram explaining the single-beam satellite communication system and multi-beam satellite communication system, Figure 6 is a diagram explaining the multi-beam satellite communication system using the conventional geostationary tether satellite (GTS), and Figure 7 is the conventional system. FIG. 3 is a diagram showing an example of an increase in communication capacity by two satellites in the GTS system compared to the above. l...Geostationary satellite orbit, 2 to 5...Satellite, 6...
・Earth, 10... Kevlar, 20... Optical fiber line, 30... Optical fiber tether line, 32 to 34.
...Satellites, 35 and 36...Inter-satellite spacing, 40...Single beam satellite communication system, 41...Multi-beam satellite communication system, 42...Beam, 43...Single beam satellite, 44. ... service area, 45 ... multiple beams, 46 ... satellite switch, 51 to 58 ... eight service areas, 61 to 6
8... 8 satellites, 69... Total satellite spacing, 71
to 77...optical fiber tether wire, 81 to 8
8...Satellite, 89...Total satellite spacing, 90...
Control signal. First Patent Applicant 1) Ken (2 others) Representative Patent Attorney
Kyotani 4th edition '1l-eAt) Optical phyno (・Stationary optical fiber to Teboo hive diagram ori Yukiaki) - Mr. Shinze 1 Figure 2 Stationary Teboo V also Figure 4 Shinkle beam Hou 1 tatami j11 method Himaru + Beam Mouse 1 star 2i power formula Figure 5

Claims (4)

[Claims] (1) Centering on one satellite in a geostationary satellite orbit, multiple satellites are placed on both sides of a straight line connecting the satellite and the center of the earth, and multiple optical fiber lines are connected between the satellites. The satellites are chained together using optical fiber tethers that enable communication and are made of thin polymer material wires with excellent strength, and the gravitational gradient caused by the difference in the gravity between the multiple satellites from the Earth always stabilizes the direction toward the center of the Earth. A geostationary optical fiber tether satellite system that consists of a geostationary satellite system that rotates at approximately the same speed as the Earth's rotation speed. (2) Set up a configuration in which the multiple satellites illuminate different service areas, perform inter-satellite relay between the multiple satellites using the optical fiber tether, and focus on the regional distribution of the service areas. The stationary optical fiber according to claim 1, wherein the arrangement order of the plurality of satellites is determined by
Tethered satellite method. (3) Transmission of supervisory control signals from the earth to all satellites or transmission of supervisory control signals from all satellites to the earth between a specified satellite and the earth station accessing the satellite; A supervisory control signal is transmitted from the satellite to the remaining satellites via the optical fiber tether line, and each satellite separates the supervisory control signal addressed to itself and performs the control instructed by the supervisory control signal. The stationary optical fiber according to claim (1), characterized in that:
Tethered satellite method. (4) A digital signal for measuring the distance between satellites is transmitted through a part of the optical fiber tether line in the optical fiber line, and when the distance between two satellites changes, that is, the length of the optical fiber tether line is determined. 2. The stationary optical fiber tether satellite system according to claim 1, wherein the distance change amount is measured by measuring a phase change of the inter-satellite distance measuring digital signal when the distance increases or decreases.