SATELLITE COMMUNICATION SYSTEM EMPLOYING UNIQUE SPOT BEAM ANTENNA DESIGN

• US 20020068526A1
• Filed: 09/14/1998
• Published: 06/06/2002
• Est. Priority Date: 09/14/1998
• Status: Active Grant

• Current Assignee: Space Systems/Loral Incorporated (Loral Space and Communications Incorporated)
• Original Assignee: Space Systems/Loral Incorporated (Loral Space and Communications Incorporated)
• Inventors: TYNER, RANDALL D., BUTTE, ERIC G.
• Granted Patent: US 6,496,682 B2
• Time in Patent Office: Days
• US Class Current: 455/13.1
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays

Abstract

A satellite communication system includes a plurality of spacecraft in geosynchronous orbit, where each spacecraft provides a plurality of beams on the surface of the earth, and a plurality of ground stations individual ones of which are located in one of the beams for transmitting uplink signals to one of the spacecraft. Each spacecraft has a plurality of receivers for receiving a plurality of the uplinked signals from ground stations, a frequency translator for translating the received uplink signals to a transmission frequency of a plurality of downlink signals, and a plurality of transmitters for transmitting the plurality of downlink signals within the same beams as the corresponding uplink signals. In accordance with the invention the beams have at least one of different sizes and shapes, including circular and elliptical, and are non-contiguous over a least a portion of the surface of the earth.

Claims

1. A communication system, comprising:

a plurality of spacecraft in geosynchronous orbit, each spacecraft cooperating to provide a plurality of beams on the surface of the earth; and

a plurality of ground stations individual ones of which are located in one of said beams for transmitting uplink signals to one of said spacecraft;

wherein

each spacecraft is comprised of a plurality of receivers for receiving a plurality of the uplinked signals from ground stations, a frequency translator for translating the received uplink signals to a transmission frequency of a plurality of downlink signals, a plurality of channel amplifiers, and a plurality of transmitters for transmitting the plurality of downlink signals within the same beams as the corresponding uplink signals; and

wherein

said beams have at least one of different sizes and shapes, and at least some of said beams are non-contiguous over a portion of the surface of the earth.

2. A system as in claim 1, wherein each of said plurality of channel amplifiers is gain controlled by a corresponding one of said ground stations.

3. A system as in claim 1, wherein the portion of the surface of the earth is CONUS.

4. A system as in claim 1, wherein uplink beams to a first one of said satellites have a first polarization and downlink beams have a second, opposite polarization, and wherein uplink beams to a second one of said satellites have said second polarization and downlink beams have said first polarization.

5. A system as in claim 1, wherein the uplink and downlink signals comprise digital data signals.

6. A system as in claim 1, wherein the uplink and downlink signals comprise digital television signals.

7. A system as in claim 6, wherein individual ones of said spot beams overlie a predetermined one of a designated television market area.

8. A system as in claim 1, wherein each spacecraft is comprised of a plurality of different sized reflector antennas for both transmitting and receiving said beams.

9. A system as in claim 1, wherein each spacecraft is comprised of a plurality of reflector antennas for both transmitting and receiving said beams, wherein at least two of said reflector antennas have different shapes.

10. A system as in claim 1, wherein each spacecraft is comprised of a plurality of reflector antennas for both transmitting and receiving said beams, wherein said plurality of reflector antennas are each comprised of a Gregorian antenna.

11. A system as in claim 1, wherein each spacecraft is comprised of a plurality of reflector antennas for both transmitting and receiving said beams, wherein said plurality of reflector antennas are each comprised of a Cassegrain antenna.

12. A system as in claim 1, wherein uplink beams to a first one of said satellites have a right hand circular polarization (RHCP) and downlink beams have a left hand circular polarization (LHCP), and wherein uplink beams to a second one of said satellites have LHCP and downlink beams have RHCP.

13. A communication satellite for providing a plurality of beams on the surface of the earth and for receiving uplink signals from a plurality of ground stations individual ones of which are located in one of said beams, said satellite comprising a plurality of receivers for receiving a plurality of the uplinked signals from ground stations, a frequency translator for translating the received uplink signals to a transmission frequency of a plurality of downlink signals, and a plurality of linearized TWTAs for transmitting the plurality of downlink signals within the same beams as the corresponding uplink signals;

wherein said beams have different sizes and one or both of a circular shape or a non-circular shape, said wherein at least some of said plurality beams are non-contiguous and non-overlapping over a least a portion of the surface of the earth.