JPH01176966A - Satellite communication/position measurement system - Google Patents

Abstract

PURPOSE:To enable communication of high quality and position measurement having no vagueness at any place on the earth by arranging >=1 communication satellite each on a stationary track on the equator and >=1 day-period track slanting to the equator surface. CONSTITUTION:The day period tracks 3 and 4 which slant at, for example, +60 deg. and -60 deg. to the equator surface are set in addition to the stationary track 2 on the equator of the earth 1, and six communication satellites S1-S6, Y1-Y6, and X1-X6 are arranged on those tracks in proper correlation. Then at least three communication satellites can easily be tracked and acquired within a 90 deg. visual field at any high-elevation position on the earth including an equator area and a polar region. Therefore, not only the communication, but also the position measurement are performed without any vagueness. At this time, those three satellites and a ground state are not on the same plane, so there is not any problem of vagueness.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to satellite communication/positioning where a large number of small earth stations including small capacity fixed stations and mobile stations perform communication and/or positioning via communication satellites. Regarding the method.

(Prior Art) With the advancement of satellite communication technology, the construction of satellite communication systems including personal micro-stations and mobile stations such as ships, aircraft, automobiles, and personal portable stations is being considered. In particular, there are great expectations for its application to mobile communications, as it can easily provide not only communications but also positioning services that instantly and accurately determine the geographic location of a mobile object.
For example, a mobile satellite communication/positioning system as shown in FIG. 3 has been proposed.

Figure 3 shows the proposal by GEO5TAR in the United States (US patent Na
4359733 Nov, 1982>, three geostationary satellites (St
, S2゜S3), communication is possible via any one of the geostationary satellites, and as shown in Figure 3(b), mobile objects can be This method enables positioning. The outline of this positioning method is as follows.

In FIG. 3(b), a mobile object located at point A transmits a short burst signal from an omnidirectional antenna to determine its position. This burst signal is transmitted to the geostationary satellite Sl,
Same S2. It is received by the base station via S3. The base station determines the propagation time tl, t2 . t3 is detected, and the position of the moving body is calculated using the principle of triangulation.

(Problems to be Solved by the Invention) However, in this GEOSTAR method, since a geostationary orbit on the equator is used, as shown in Figure 3 (b), the same conditions are applied to point B, which is exactly symmetrical to point A with respect to the equatorial plane. There are points that satisfy the following. In other words, it is impossible to distinguish between points A and B. Therefore, unless the mobile units know by other means whether their position is in the southern hemisphere or the northern hemisphere, the above ambiguity cannot be resolved. Therefore, positioning services for mobile objects moving near the equator are extremely difficult.

The fourth method does not cause the above-mentioned difficulties regarding positioning.
GPS (General Position) shown in the figure.
There is a system (onning system). This GPS system does not use a geostationary orbit 2 located on the equator of the earth 1, but uses a low-altitude orbit 5 set at half the altitude of this geostationary orbit 2. That is, a total of 18 low-altitude orbits 5 are provided, and a mobile object receives signals from 4 of the 18 communication satellites on these low-altitude orbits 5 and calculates the propagation time difference of the signals. It detects it and calculates its own position. Therefore, positioning can be performed without causing the problem of ambiguity. However, the purpose of this GPS system is positioning, and there is a problem in that it has no communication function at all.

Furthermore, all conventional commercial satellite communications use geostationary orbits above the equator, which are already quite congested and have become a barrier to the advancement of satellite communications. Furthermore, since a geostationary orbit above the equator has a low elevation angle in high latitude regions, when using a low-directivity antenna like a mobile object, there may be deterioration in line quality due to multipath fading or shielding effects such as trees or topography. There are various problems such as unavoidable problems such as communication interruption due to

The present invention was developed in view of these problems, and its purpose is to dramatically expand the communication capacity of satellite communication as a whole, and to enable high-angle, high-quality communication to be carried out anywhere on the earth. It is an object of the present invention to provide a satellite communication/positioning method that can perform positioning without any ambiguity.

(Means for Solving the Problems) In order to achieve the above object, the satellite communication/positioning system of the present invention has the following configuration.

In other words, the satellite communication/positioning system of the present invention is applicable to small-capacity fixed stations,
A satellite communication/positioning method in which a large number of small earth stations, including mobile stations, perform communication and/or positioning via communication satellites; and one or more diurnal orbits that are inclined with respect to the equatorial plane, and one or more communication satellites are placed in each of the orbits, and each small earth station is located at a high elevation angle with respect to the own station. It is characterized by performing communication and/or positioning via one or more communication satellites.

(Function) Next, the function of the satellite communication/positioning system of the present invention configured as described above will be explained.

The communication satellite according to the present invention has one or more communication satellites arranged in each of a geosynchronous orbit that is a diurnal orbit on the equator and one or more diurnal orbits that are inclined with respect to the equatorial plane. Consists of satellites. In other words, communication satellites on each orbit are equidistant from the earth, and communication satellites on diurnal orbits that are inclined to the equatorial plane move slowly in a north-south direction when viewed from the ground. Therefore, since satellite tracking is easy, communication satellites can be captured at high elevation angles even in high latitude regions. By making it possible to capture at least three of the communication satellites on a plurality of diurnal orbits within a high elevation field of view, unambiguous positioning can be performed instantly.

Thus, according to the satellite communication/positioning system of the present invention, communication satellites are arranged on a large number of diurnal orbits, so that the communication capacity of the entire satellite communication can be dramatically increased. Furthermore, since high-elevation angle communication is possible anywhere on the earth, high-quality communication is possible without the influence of multipath fading or the shielding effects of trees, topography, etc. Furthermore, if applied to mobile satellite communications, it will become possible to perform instant high-precision positioning anywhere on the globe, including equatorial and polar regions, without causing the ambiguity that occurs with the conventional GEOSTAR method. There are other effects.

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

Figure 1 shows a satellite communication/positioning system according to an embodiment of the present invention.6 In this embodiment, in addition to the geostationary orbit 2 which is a diurnal orbit above the equator of the earth 1, the A diurnal orbit 4 and a diurnal orbit 3 tilted by 160 degrees are set respectively, and six communication satellites (st to S
6. Y, ~Y6°X1~X6) are arranged in an appropriate relative relationship.

As is well known, a diurnal orbit is an orbit whose revolution period coincides with one day, and a geostationary orbit is one type of this orbit, which is special in that its orbital plane coincides with the equatorial plane. in general,
Communication satellites in diurnal orbits move slowly in a north-south direction when viewed from the ground. Therefore, communication satellites can be easily tracked and captured at high elevation angle positions anywhere on the earth, including equatorial and polar regions.

If six communication satellites are placed in each orbit as shown in Figure 1, at least three communication satellites will be within a 90-degree field of view in a place on the earth, and not only communication but also Positioning can also be performed without creating ambiguity as in the conventional method.

Next, the positioning method according to the present invention will be explained with reference to FIG. FIG. 2 shows the positional relationship of the communication satellites as seen from the normal direction of the orbital plane of the diurnal orbit 3.

Therefore, the diurnal orbit 3 appears to be a circle, and the geostationary orbit 2 appears to be an ellipse.

In FIG. 2, in the area from point F to point G on the ground, communication satellites X 1 + x2 and geostationary satellite Sl are in the field of view. Therefore, the moving body at point A in the diagram is
Propagation time t of signals from each satellite + 81 + X 2
1+same t2. The own position can be calculated by detecting the time difference between t3. At this time, since these three satellites are not on the same plane, the problem of the degree of overlap that occurs in the conventional method does not occur.

As is clear from the above explanation, communication is possible using satellites located at high elevation angles on the earth, so by increasing the number of satellites in diurnal orbits sufficiently, conventional mobile satellite communication The problems of multipath fading and shielding effects of trees, topography, etc., which were major problems in the past, do not occur.In other words, the present invention allows high-quality communication and positioning to be performed anywhere on the earth.

(Effects of the Invention) As explained above, according to the satellite communication/positioning method of the present invention, since communication satellites are placed on a large number of diurnal orbits,
The communication capacity of the entire satellite communication system can be dramatically increased.

Furthermore, since high-elevation angle communication is possible in places on the earth, high-quality communication is possible without the influence of multipath fading or shielding effects such as trees and topography. Furthermore, if applied to mobile satellite communications, it will become possible to perform instant high-precision positioning anywhere on the globe, including equatorial and polar regions, without causing the ambiguity that occurs with the conventional GEOSTAR method. There are other effects.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of the structure of the satellite communication/positioning method of the present invention, Fig. 2 is an explanatory diagram of the principle of positioning according to the present invention, and Fig. 3 shows the structure and positioning method of the conventional mobile satellite communication/positioning method. 4 are diagrams showing the conventional satellite positioning system (GPS). 1...Earth, 2...Geostationary orbit, 3
．． 4...Diurnal orbit inclined with respect to the equatorial plane, S1 to S6. X1 to X6. Y, ~Y6...
communication satellite. Agent: Patent Attorney Yoshihiro Hachiman
l Figure 2, History of positioning by invention 12 illustrations 2 Figure 5 EO 3 ARzu) K (a) Δ shi 2 J I f L 6 7 traps, pattern (b) /--1- Sword begging i1ζ, 2-,, pot? 5 Hee Dai Ni! , S+~53--・--3 matured Jin Ine Kencho Hoshiba 5 昚/l 蔚(gaban 4 酊星 u/; carved oinuta 3 fig., Go--11 I expulsion) Shu 1 Giant] Light 1 x Pilt /) #L 31 SumyA' (GPS O) Figure 4

Claims (1)

[Claims] A satellite communication/positioning method in which a large number of small earth stations, including small-capacity fixed stations and mobile stations, perform communication and/or positioning via communication satellites;
1 for each of a geostationary orbit that is a diurnal orbit on the equator and one or more diurnal orbits that are inclined with respect to the equatorial plane.
A satellite characterized in that one or more communication satellites are arranged, and each small earth station performs communication or positioning, or both, via one or more communication satellites located at a high elevation angle relative to its own station. Communication/positioning method.