Geosynchronous satellite constellation

• US 20060240767A1
• Filed: 11/28/2005
• Published: 10/26/2006
• Est. Priority Date: 03/16/2005
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Brown, David M., Jacomb-Hood, Anthony W.
• Granted Patent: US 7,519,324 B2
• Time in Patent Office: Days
• US Class Current: 455/12.100
• CPC Class Codes: B64G 1/1085 Swarms and constellations
• CPC Class Codes: H04B 7/19 Earth-synchronous stations

Abstract

A satellite communications system is described for increasing capacity through spectrum reuse by multiple satellites. The system includes a constellation of satellites traveling in a geosynchronous orbit, where the geosynchronous orbit defines a satellite track. The satellite track of the constellation overlaps a geostationary orbital location occupied by a legacy satellite traveling in a geostationary orbit. To prevent interference between the co-located constellation and legacy satellite, each of the constellation satellites operates in a silent mode when traveling within an interference beam width of a ground terminal in communication with the legacy satellite. Once outside of the interference beam width, the constellation satellites return to an active mode of operation.

Claims

1. A satellite constellation comprising a plurality of satellites traveling in a geosynchronous orbit, the geosynchronous orbit defining a satellite track,

wherein the satellite track overlaps a geostationary orbital location occupied by a legacy satellite traveling in a geostationary orbit, and

wherein each of said plurality of satellites operates in a silent mode when traveling within an interference beam width of a ground terminal in communication with the legacy satellite and in an active mode when traveling outside the interference beam width of the ground terminal.

2. The satellite constellation according to claim 1, wherein each of said plurality of satellites operates in a first active mode when traveling in a first latitudinal direction on the satellite track outside the interference beam width of the ground terminal and in a second active mode when traveling in a second latitudinal direction on the satellite track outside the interference beam width of the ground terminal, and

wherein satellites traveling in the first latitudinal direction maintain a minimum spacing apart from each other and satellites traveling in the second latitudinal direction maintain the minimum spacing apart from each other.

3. The satellite constellation according to claim 2, wherein the minimum spacing is a spacing necessary to prevent interference between adjacent satellites.

4. The satellite constellation according to claim 1, wherein the satellite track is an elongated satellite track, wherein the latitudinal excursion of the satellite track is greater than the longitudinal excursion of the satellite track.

5. The satellite constellation according to claim 1, wherein said plurality of satellites and the legacy satellite use overlapping portions of a common frequency band.

6. The satellite constellation according to claim 5, wherein said plurality of satellites cease transmission of communication signals within the overlapping portions of the common frequency band when operating in the silent mode.

7. The satellite constellation according to claim 1, wherein said plurality of satellites cease transmission of all communication signals when operating in the silent mode.

8. A satellite communications system, comprising:

a plurality of satellites traveling in a geosynchronous orbit, the geosynchronous orbit defining a satellite track; and

a first ground terminal for communicating with at least one of said plurality of satellites,

wherein the satellite track overlaps a geostationary orbital location occupied by a legacy satellite traveling in a geostationary orbit, and

wherein each of said plurality of satellites operates in a silent mode when traveling within an interference beam width of a second ground terminal in communication with the legacy satellite and in an active mode when traveling outside the interference beam width of the second ground terminal.

9. The satellite communications system according to claim 8, wherein each of said plurality of satellites operates in a first active mode when traveling in a first latitudinal direction on the satellite track outside the interference beam width of the second ground terminal and in a second active mode when traveling in a second latitudinal direction on the satellite track outside the interference beam width of the ground terminal, and

wherein satellites traveling in the first latitudinal direction maintain a minimum spacing apart from each other and satellites traveling in the second latitudinal direction maintain the minimum spacing apart from each other.

10. The satellite communications system according to claim 9, wherein the minimum spacing is a spacing necessary to prevent interference between adjacent satellites.

11. The satellite communications system according to claim 8, wherein the satellite track is an elongated satellite track, wherein the latitudinal excursion of the satellite track is greater than the longitudinal excursion of the satellite track.

12. The satellite communications system according to claim 8, wherein said first ground terminal comprises an antenna system for selectively steering beams at said plurality of satellites.

13. The satellite communications system according to claim 12, wherein said antenna system selectively steers nulls at said plurality of satellites.

14. The satellite communications system according to claim 13, wherein said antenna system selectively steers a null at the legacy satellite.

15. The satellite communications system according to claim 8, wherein said first ground terminal is capable of communicating with the legacy satellite.

16. The satellite communications system according to claim 8, wherein said plurality of satellites and the legacy satellite use overlapping portions of a common frequency band.

17. The satellite communications system according to claim 16, wherein said plurality of satellites cease transmission of communication signals within the overlapping portions of the common frequency band when operating in the silent mode.

18. The satellite communications system according to claim 8, wherein said plurality of satellites cease transmission of all communication signals when operating in the silent mode.

19. A satellite communications system, comprising:

a plurality of satellites traveling in a geosynchronous orbit, the geosynchronous orbit defining a satellite track;

a legacy satellite traveling in a geostationary orbit;

a first ground terminal for communicating with at least one of said plurality of satellites and said legacy satellite,

wherein the satellite track overlaps a geostationary orbital location occupied by said legacy satellite, and

wherein each of said plurality of satellites operates in a silent mode when traveling within an interference beam width of a second ground terminal in communication with said legacy satellite and in an active mode when traveling outside the interference beam width of the second ground terminal.

20. The satellite communications system according to claim 19, wherein each of said plurality of satellites operates in a first active mode when traveling in a first latitudinal direction on the satellite track outside the interference beam width of the second ground terminal and in a second active mode when traveling in a second latitudinal direction on the satellite track outside the interference beam width of the ground terminal, and

wherein satellites traveling in the first latitudinal direction maintain a minimum spacing apart from each other and satellites traveling in the second latitudinal direction maintain the minimum spacing apart from each other.

21. The satellite communications system according to claim 20, wherein the minimum spacing is necessary to prevent interference between adjacent satellites.

22. The satellite communications system according to claim 21, wherein the satellite track is an elongated satellite track, wherein the latitudinal excursion of the satellite track is greater than the longitudinal excursion of the satellite track.

23. The satellite communications system according to claim 19, wherein said first ground terminal comprises an antenna system for selectively steering beams at said plurality of satellites and said legacy satellite.

24. The satellite communications system according to claim 23, wherein said antenna system selectively steers nulls at said plurality of satellites and said legacy satellite.

25. The satellite communications system according to claim 19, wherein said plurality of satellites and said legacy satellite use overlapping portions of a common frequency band.

26. The satellite communications system according to claim 25, wherein said plurality of satellites cease transmission of communication signals within the overlapping portions of the common frequency band when operating in the silent mode.

27. The satellite communications system according to claim 19, wherein said plurality of satellites cease transmission of all communication signals when operating in the silent mode.