JPH03278726A - Data repeat satellite system - Google Patents

Abstract

PURPOSE:To distribute a data from a spacecraft continuously to the user on ground by arranging two data repeat satellites whose longitude is apart nearly by 180 deg. onto a counter-ground stationary orbit, arranging an earth station to a longitude respectively close to the stationary orbit and connecting the earth station with on-ground network. CONSTITUTION:The system consists of two data repeat satellites 1, 2 arranged to a counter-ground stationary orbit whose longitude is apart nearly by 180 deg. arranged, two earth stations 3, 4 arranged to the longitude close to the data repeat satellites 1, 2 and an on-ground network 5 interconnecting the two earth stations 3, 4. Thus, any of the data repeat satellites on two counter-ground stationary orbits whose longitude is apart nearly by 180 deg. at all times is in a visible area of a spacecraft circulating on a low altitude orbit whose altitude is less than 1200km and more than 73km and a data from the spacecraft 6 is sent to the earth station 3 or 4 via the data repeat satellites 1, 2. Thus, the data from the spacecraft 6 is continuously transmitted onto ground.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a data relay satellite system, and is particularly applicable to continuous data transmission from a spacecraft orbiting the earth in a low orbit at an altitude of 1200 km or less, such as a space station. This invention relates to a data relay satellite system in which a data transmission system capable of acquiring data on the ground is constructed using the smallest data relay satellite.

[Conventional technology]

Conventionally, this type of data relay satellite system has a longitude of approximately 1
It consisted of two data relay satellites in geostationary orbit 30 degrees apart and one earth station.

FIG. 3 is a configuration diagram of a conventional data relay satellite system. As is clear from FIG. 3, conventional data relay satellites are separated by about 130 degrees from each other, one earth station 9 performs data relay, and the spacecraft 6 orbits along the orbit 8 of the spacecraft around the Earth 7. As shown by the diagonal lines in Figure 3, there is an invisible area 1o where neither the data relay satellites 1 nor 2 are visible. It is a diagram showing visible time periods.

[Problem to be solved by the invention]

The conventional data relay satellite system described above has a longitude of approximately 1
It consists of two data relay satellites in geostationary orbit with 30 degrees of rotation, so there is no space between the data relay satellite and a spacecraft orbiting the earth in low orbit at an altitude of 1,200 km or less, such as a space station. Since there is an invisible area,
It is said that continuous data transmission is not possible, and to solve this problem, a separate data relay satellite is needed in addition to the conventional data relay satellite.

In addition, in the conventional data relay satellite system, one earth station accesses two data relay satellites in geostationary orbit whose longitudes have changed by about 130 degrees, so each antenna of the earth station transmits data at a low elevation angle. As relay satellites are tracked, a lot of rain loss occurs during rainy seasons, which degrades the data quality of the line. The disadvantage is that geographical restrictions on the installation location cannot be avoided.

[Means for Solving the Problems] The data relay satellite system of the present invention continuously acquires data on the ground from a spacecraft such as a space station orbiting the earth in a low orbit, so that the data relay satellite system of the present invention has a longitude of about 180 degrees. The satellite has two data relay satellites placed in a geosynchronous orbit, two earth stations placed at longitudes close to each of the data relay satellites, and a ground network connecting the two earth stations. It is composed of

Further, the data relay satellite system of the present invention has a configuration that targets the spacecraft whose low orbit is 1200 Km or less and 73 Km or more.

〔Example〕

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

FIG. 1 is a configuration diagram of an embodiment of the data relay satellite system of the present invention.

In Figure 1, 1.2 is a data relay satellite in geosynchronous orbit, 3 and 4 are earth stations corresponding to each of the data relay satellites, 5 is a ground network connecting the two earth stations, and 6 is a distance of 1200 km or less. Spacecraft orbiting in low orbit, 7
is the earth.

FIG. 2 is a diagram showing the visible time period when the data relay satellite is viewed from the spacecraft 6 orbiting in a low orbit of 1200 km or less according to the present invention. As is clear from Figure 2, approximately 73
The data relay satellite 1 or 2 can always be seen from the spacecraft 6 orbiting at an altitude of Km or higher, and the earth station 3 or 4 can always communicate with the spacecraft 6. Therefore, by connecting the earth station 3 and the earth station 4 through a ground network, it becomes possible to continuously distribute data from space tR6 to users on the ground.

In this way, the data relay satellite system of the present invention
Connects two data relay satellites 1.2 on geosynchronous orbits whose longitudes can be changed by about 180 degrees, two earth stations 3 and 4 corresponding to each data relay satellite, and earth station 3.4. Altitude 1200Km with terrestrial network 5
From a spacecraft orbiting in a low orbit of 73 km or higher, one of the two data relay satellites in geosynchronous orbit is always in the visible range, and therefore data from Spacecraft 6 is always visible. will be transmitted to the earth station 3 or 4 via two data relay satellites 1.2. The two earth stations 3 and 4 are connected by a ground network, so that data from the spacecraft 6 can be continuously transmitted to the ground.

In addition, the earth stations corresponding to the two data relay satellites in geostationary orbit, whose longitudes can be changed by approximately 180 degrees, are placed at longitudes close to the geostationary positions of the respective data relay satellites. Since the antenna can track data relay satellites at high elevation angles, it can be operated with less rain loss during rainy days, improving the data quality of the line.

〔Effect of the invention〕

As explained above, in the present invention, two data relay satellites whose longitudes can be varied by about 180 degrees are placed in geosynchronous orbit, and an earth station is placed at a longitude close to the geostationary position of each data relay satellite. However, by connecting these earth stations with a ground network, the following effects can be obtained.

(1) Only two data relay satellites are required to continuously communicate with a spacecraft in a low orbit at an altitude of approximately 70 km or more and 1,200 km or less.

(2) Communication between the earth station and the data relay satellite uses a frequency band such as the Ka band, which increases rainfall attenuation and atmospheric attenuation between the earth station and the earth station. Since it can track data relay satellites at high elevation angles, it can be operated with significantly less rain attenuation and atmospheric attenuation than conventional systems, making it possible to improve the data quality of communication lines.

(3) Compared to a system consisting of three data relay satellites, the system can be simplified and can be operated at low cost.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an embodiment of the data relay satellite system of the present invention, Fig. 2 is a diagram showing the visible time zone from the spacecraft to the data relay satellite in the embodiment of Fig. 1, and Fig. 3 is a diagram of the conventional data relay satellite system. FIG. 4 is a block diagram of the data relay satellite system shown in FIG. 1.2... Data relay satellite, 3.4... Earth station, 5
...Ground network, 6.. Spacecraft, 7.. Earth, 8.. Orbit of spacecraft, 10.. Invisible region.

Claims (1)

[Claims] 1. In order to continuously acquire data on the ground from a spacecraft such as a space station orbiting the earth in low orbit, two spacecraft are placed in geostationary orbit approximately 180 degrees apart in longitude. A data relay satellite system comprising a data relay satellite, two earth stations located at longitudes close to each of the data relay satellites, and a ground network connecting the two earth stations. 2. The low orbit of the spacecraft is 1200 km or less, and
2. The data relay satellite system according to claim 1, wherein the data relay satellite system has a distance of 3 km or more.