JPS6343021B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multiple access system for data relay satellites. This data relay satellite (here TRACKING AND DATA RELAY)
SAT ELLTE: Hereinafter referred to as TDRS. ) is launched into a geostationary orbit, and is connected to a control station that is an earth station.
TDRS is connected by a feeder link line, and serves as a space station controlled by instructions from a control station.
TDRS works. The main function of TDRS is to configure a communication line between other artificial satellites orbiting the earth (hereinafter referred to as user satellites) in geostationary orbit, and the control station can communicate with user satellites via TDRS. It performs data communication between.
TDRS uses multiple access (hereinafter referred to as inter-satellite communication) as a line between user satellites (hereinafter referred to as inter-satellite communication).
MA), two types of single access (hereinafter referred to as MA), and two types of single access (hereinafter referred to as
There are three types of lines (called SA), and the frequency of MA is S band, and the forward line (line from TDRS to the user satellite) electronically controls the beam direction from TDRS and maintains the data line with the user satellite. and return line (from user satellite
The line to TDRS) is a line that electronically processes data from multiple user satellites so that it can receive it simultaneously, and the SA frequency is the S band and K band, and both the forward line and return line are mechanically controlled antennas. This line performs high-speed data transmission between user satellites and user satellites. The MA is used primarily to receive telemetry, send commands, and send and receive range and range rate signals. TDRS
MA is designed to be able to establish a link with user satellites on the earth's surface, including outer space, in satellite orbits at an altitude of about 1000 km above the earth's surface.

Figure 1 shows the arrangement of TDRS in orbit and 2
The area covered by the two TDRSs is shown below, and the operating principle is briefly explained below.

In Figure 1, 1 is stationary in a geostationary orbit at 41 degrees east longitude at TDRS1. 2 is TDRS2 and remains stationary in a geostationary orbit at 171 degrees west longitude. 3 is the earth, and 4 is an orbiting satellite. The tangents of TDRS1 and 2 and Earth 3 are 5, 6,
Shown in 7 and 8. Range 9, which cannot be seen directly from either TDRS 1 or 2, cannot be controlled by TDRS, but the orbit of the user satellite surrounded by tangents 5, 6, 7, and 8, and the area around the earth in a surrounding orbit of about 1000 km. In space, user satellites can be controlled by TDRS. The MA consists of an array antenna consisting of a large number of antenna elements, and its typical irradiation pattern on the ground surface is shown in Figure 2.
The configuration of the MA antenna pattern will be explained below. In FIG. 2, 10 is the edge of the earth as seen from the data relay satellite. 11, 12, 13, 14 on earth using antenna elements of data relay satellites.
Create a beam spot like this. The position, number, and gain of the beam spots are determined by the number, arrangement, and electrical characteristics of the element antennas. In the return line of the MA antenna, if the signals are transmitted from different spots at the same time, it is possible to distinguish between the two on the receiving side.In particular, each channel to be transmitted uses an orthogonal code that has extremely high autocorrelation characteristics. If a pseudo random code is assigned, each channel can be easily identified.
In TDRS, the signals received by the antennas that form each beam are sent to the earth station by establishing a transmission path for each antenna, and the earth station uses AGIPA (AGIPA), which combines the waveforms so that the peak value of the beam points in the direction in which it was transmitted. Adaptive
Ground Implemented Phased Array) system. In this way, there are methods that move the receiving beam depending on the target, and methods that fix the receiving beam at a more or less fixed location, but in either case, the main mission of the return line is to receive telemetry signals from user satellites. Therefore, it is required to constantly receive signals from user satellites. For this purpose, the ability to simultaneously receive signals from many satellites and output them separately is required, and the method described above is required.

Since the forward line of the MA antenna is mainly used for transmitting commands, it is not required to transmit commands to user satellites at all times. For this reason, only one transmission beam is required, and it is sufficient if the beam can scan the same area covered by the spot beam shown in FIG. When it is necessary to send commands to many user satellites, a specific phase is given to the MA antenna element and the beam is scanned. In this manner, the return and forward links of data relay satellites are generally configured.

If a data relay satellite with such performance is used to control a user satellite in a transition orbit of a geostationary satellite, the coverage will be insufficient with just a spot beam as shown in Figure 2. In order to expand the coverage area with the current antenna configuration, it is necessary to electrically scan the beam more than now using phase synthesis, but with an antenna that has a beam coverage area as shown in Figure 2 due to phase synthesis, If the beam is scanned beyond the beam range shown in Figure 2, the effect of grading lobes will occur within the original beam range, causing radio waves to be emitted to unnecessary areas or conversely from unexpected places. Because it receives noise,
In order to avoid this, it is necessary to increase the number of antenna elements, which tends to increase the aperture of the data relay satellite and increase its weight, which are undesirable trends for space equipment. If you try to expand and use the MA system of a conventional data relay satellite, the problems mentioned above will occur. Therefore, this invention
A gimbal mechanism is installed where the MA antenna is attached to the satellite, so that the MA antenna is mechanically movable relative to the satellite body, and the electrical scanning function and mechanical movable function of the antenna are combined,
This is an expanded version of the scanning range of the MA antenna, and a detailed explanation is provided below using the drawings. FIG. 3 is a diagram showing the side of the data relay satellite facing toward the earth. In the figure, 15 is an MA antenna, 16 is the satellite body, 17 is a solar panel, 18 is a single access antenna, and 19 is a feeder antenna used for a line with a control earth station.
Figure 4 shows this satellite viewed from the side.
FIG. 5 is a diagram showing the configuration of a satellite including the gimbal mechanism according to the present invention, and the satellite is viewed from the same viewpoint as FIG. 4. The MA antenna 15 and the satellite body 16 are coupled by a gimbal mechanism 20. FIG. 6 is a three-dimensional view of a multi-beam antenna with a gimbal mechanism. M.A.
In order to clearly indicate the direction of rotation of the antenna, coordinates are defined from the center 21 of the MA antenna. 22 is the center of coordinates, 23 is the yaw axis in the direction in which the satellite points toward the earth, 25 is the roll axis, and 24 is the pitch axis.
The MA antenna 15 is operated by the gimbal movable part 20.
It can rotate in the roll axis direction and pitch axis direction. The antenna element of MA antenna 15 is mounted on its surface. The input and output of the antenna element are connected to the diplexer and transmitter/receiver via the feed line, and these are connected to the MA antenna 15.
It is also possible to attach the diplexer and transmitter to the back side of the satellite body 1 by passing the feeder cable between the MA antenna 15 and the satellite body 16.
You can also set it to 6. FIG. 7 is a diagram showing the state when the MA antenna 15 is rotated by approximately the viewing angle by the gimbal drive mechanism.
26 and 27 show the enlarged field of view of data relay satellite 1, and 28 and 29 show the enlarged field of view of data relay satellite 2. 30
shows a geostationary satellite about to fly into a transition orbit. 31 is a transition orbit. According to this invention, the range of user satellites that can be controlled by conventional data relay satellites are low-altitude orbiting satellites, but in data relay satellites equipped with a gimbal mechanism according to this invention, the MA antenna can be mechanically rotated. At the same time, by combining this with an electronic scanning function, the range in which user satellites can be controlled can be greatly expanded.

[Brief explanation of drawings]

Figure 1 shows the control range of the conventional TDRS, Figure 2 shows the beam spot on the ground surface of the multiple access antenna, Figure 3 shows an example of a data relay satellite, and Figure 4 also shows the control range of the conventional TDRS. Data relay satellite 1
Figure 5 is a diagram showing an example of how the MA antenna according to the present invention is attached to a data relay satellite, and Figure 6 is a three-dimensional diagram showing how the MA antenna according to the present invention is attached to a data relay satellite. 7 are diagrams showing an enlarged control range of the data relay satellite according to the present invention. In the diagram, 1 is TDRS1, 2 is TDRS2, 3 is Earth, 4
is the orbiting satellite, 5, 6, 7, 8 are tangents, 9 is the invisible area, 10 is the edge of the earth, 11, 12, 13, 14
is the spot beam, 15 is the MA antenna, 16 is the satellite body, 17 is the solar panel, 18 is the single access antenna, 19 is the feeder link antenna, 20 is the gimbal drive unit, 21 is the center of the MA antenna, 22 is the coordinates 23 is the yaw axis, 24 is the pitch axis, 25 is the roll axis, 26,2
7, 28, and 29 are fields of view, 30 is a user satellite in a transfer orbit, and 31 is a transition orbit of a geostationary satellite. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

Claims (1)

[Claims] 1 In the multiple access system for data relay satellites that transmit information using radio waves with other artificial satellites in response to control signals from a control earth station in geostationary orbit, a multiple access antenna and this multiple access antenna are A multiple access system for a data relay satellite, characterized in that a gimbal mechanism movable in the axial direction is provided on the data relay satellite main body, and antenna beams synthesized by the multiple access antenna are moved electrically and mechanically.