Molniya orbit satellite systems, apparatus, and methods

• US 7,840,180 B2
• Filed: 12/22/2006
• Issued: 11/23/2010
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Rosen, Harold A.
• Primary Examiner(s): TRINH, TAN H
• Application Number:
  US11/615,774
• Publication Number:
  US 20080155610A1
• Time in Patent Office: 1,432 Days
• Field of Search: 455/12.1, 455/13.2, 455/63.4, 455/25, 455/431, 455/427, 455/3.06, 455/3.02, 455/3.03, 455/73, 455/517, 455/345, 725/68, 725/69, 725/71, 725/100, 725/64, 725/63, 725/78, 725/80, 370/316
• US Class Current: 455/12.1
• CPC Class Codes: H04B 7/18523 Satellite systems for providing broadcast service to terrestrial stations, i.e. broadcast satellite service arrangements specially adapted for satellite broadcast receiving H04H40/90; picture transmission via satellite H04N1/00103; television transmission via satellite H04N7/20
• CPC Class Codes: H04N 7/20 Adaptations for transmission via a GHz frequency band, e.g. via satellite

Abstract

A system includes a satellite fleet (102, FIG. 1), in which each satellite receives uplink signals from an uplink hub (104), and transmits downlink signals in at least one directed beam (112). In an embodiment, downlink signals include television content, which is transmitted within a frequency range between about 3.7 and 4.2 Gigahertz. The satellites follow Molniya orbits (1001-1006, FIG. 10), orbit nodes are equally separated, and the satellite phasing is maintained to provide continuous communication within a coverage area. A system also includes user equipment systems (1300, FIG. 13), which include highly-directional, non-tracking antennas (1302) adapted to receive the downlink signals. In an embodiment, a method includes the satellites maintaining orbit phasings, with respect to other satellites, so that the satellite enters an active orbit segment and initiates transmission of downlink signals as a second satellite exits an active orbit segment and ceases transmission of the downlink signals.

Claims

1. A system, comprising:

a plurality of satellites, wherein each satellite of the plurality of satellites is adapted to receive uplink signals from at least one uplink hub, and to transmit downlink signals toward Earth in at least one directed beam, and wherein orbit paths of the plurality of satellites are Molniya orbits with an orbital period of about 12 hours and an angle of inclination of about 63.4 degrees, and wherein the plurality of satellites track along a substantially fixed path on the surface of the Earth over which each of the plurality of satellites travels during an orbit of the satellite, and wherein the plurality of satellites are phased in their orbits so that a first satellite enters an active orbit segment of the first satellite and initiates transmission of the downlink signals as a second satellite exits an active orbit segment of the second satellite and ceases transmission of the downlink signals, wherein an active orbit segment is centered about an apogee and has a duration of a sidereal day divided by a total number of satellites in the plurality of satellites;

a plurality of user equipment systems located proximate to a surface of the Earth, wherein a user equipment system includes a highly-directional, non-tracking antenna adapted to receive the downlink signals, wherein the active orbit segment of each of the satellites is configured to transmit downlink signals to the plurality of highly-directional non-tracking antennas, and wherein each of the plurality of non-tracking antennas do not include a tracking mechanism adapted to dynamically point toward and track a satellite from which each highly-directional non-tracking antenna is receiving a transmission; and

wherein each of the plurality of highly-directional non-tracking antennas are configured to receive the downlink signals transmitted by a satellite of the plurality of satellites while the satellite is within an active orbit segment.

2. The system of claim 1, further comprising:

the at least one uplink hub, which is adapted to transmit the uplink signals toward each satellite of the plurality of satellites.

3. The system of claim 1, further comprising:

a plurality of user equipment systems located proximate to a surface of the Earth, wherein a user equipment system includes a highly-directional, non-tracking antenna adapted to receive the downlink signals, and wherein the highly-directional antenna is an antenna with a directivity greater than or equal to one hundred times that of an omnidirectional antenna.

4. The system of claim 1, wherein the plurality of satellites includes six satellites.

5. The system of claim 1, wherein each satellite is adapted to receive uplink television signals and to broadcast downlink television signals.

6. The system of claim 1, wherein each satellite is adapted to transmit the downlink signals during the active orbit segment and to avoid transmitting the downlink signals during an inactive orbit segment.

7. The system of claim 1, wherein each satellite transmits the downlink signals within a frequency range between 3.7 and 4.2 Gigahertz.

8. A satellite system, comprising:

at least one uplink antenna subsystem adapted to receive uplink signals from at least one uplink hub;

at least one downlink antenna subsystem adapted to transmit downlink signals toward the Earth in at least one directed beam; and

a stationkeeping subsystem adapted to maintain the satellite in a Molniya orbit with an orbital period of about 12 hours and an angle of inclination of about 63.4 degrees, and to maintain an orbit phasing of the satellite, with respect to other satellites within a satellite fleet, so that the satellite enters an active orbit segment of the satellite and initiates transmission of the downlink signals as a second satellite exits an active orbit segment of the second satellite and ceases transmission of the downlink signals, wherein an active orbit segment is centered about an apogee and has a duration of a sidereal day divided by a total number of satellites in the satellite fleet, wherein the satellite and all other satellites within the satellite fleet track along a substantially fixed path on the surface of the Earth over which each of the plurality of satellites travels during an orbit of the satellite and wherein the active orbit segment of each of the satellites is configured to transmit downlink signals to a plurality of highly-directional non-tracking antennas, and wherein each of the plurality of highly-directional non-tracking antennas do not include a tracking mechanism adapted to dynamically point toward and track a satellite from which each highly-directional non-tracking antenna is receiving a transmission;

wherein each of the plurality of highly-directional non-tracking antennas are configured to receive the downlink signals transmitted by a satellite of the plurality of satellites while the satellite is within the active orbit segment and wherein the highly-directional antenna is an antenna with a directivity greater than or equal to one hundred times that of an omnidirectional antenna.

9. The satellite system of claim 8, further comprising:

a communications subsystem adapted to transmit the downlink signals during the active orbit segment, and to avoid transmitting the downlink signals during an inactive orbit segment.

10. A user equipment system comprising:

a highly-directional, non-tracking antenna, which is adapted to receive downlink signals transmitted by a satellite of a satellite fleet while the satellite is within an active orbit segment, wherein the active orbit segment is centered about an apogee having a duration of a sidereal day divided by a total number of satellites in the satellite fleet, wherein the satellite and all other satellites within the satellite fleet track along a common ground track.

11. The user equipment system of claim 10, wherein the highly-directional, non-tracking antenna is adapted to receive the downlink signals at frequencies within a range of about 3.7 to 4.2 Gigahertz and wherein the highly-directional antenna is an antenna with a directivity greater than or equal to one hundred times that of an omnidirectional antenna.

12. The user equipment system of claim 10, further comprising:

the set top box adapted to provide an interface between the highly-directional, non-tracking antenna and a television set to enable the television set to display audio and video content within a selected channel.

13. A method performed by a satellite, the method comprising:

maintaining the satellite in a Molniya orbit with an orbital period of about 12 hours, an angle of inclination of about 63.4 degrees;

maintaining an orbit phasing of the satellite, with respect to other satellites within a satellite fleet, so that the satellite enters an active orbit segment of the satellite and initiates transmission of downlink signals as a second satellite exits an active orbit segment of the second satellite and ceases transmission of the downlink signals, wherein an active orbit segment is centered about an apogee and has a duration of a sidereal day divided by a total number of satellites in the satellite fleet, and wherein the satellite and all other satellites within the satellite fleet track along a substantially fixed path on the surface of the Earth over which each of the plurality of satellites travels during an orbit of the satellite and wherein the active orbit segment of each of the satellites is configured to transmit downlink signals to a plurality of highly-directional non-tracking antennas, and wherein each of the plurality of highly-directional non-tracking antennas do not include a tracking mechanism adapted to dynamically point toward and track a satellite from which each highly-directional non-tracking antenna is receiving a transmission;

wherein each of the plurality of highly-directional non-tracking antennas are configured to receive the downlink signals transmitted by a satellite of the plurality of satellites while the satellite is within the active orbit segment and wherein the highly-directional antenna is an antenna with a directivity greater than or equal to one hundred times that of an omnidirectional antenna;

receiving an uplink signal from at least one uplink hub; and

transmitting the downlink signals toward Earth in at least one directed beam.

14. The method of claim 13, wherein maintaining the orbit further comprises:

maintaining the orbit with an apogee above 60 degrees North latitude.

15. The method of claim 13, wherein maintaining the satellite in the Molniya orbit further comprises:

maintaining an orbit with an apogee below 60 degrees South latitude.

16. The method of claim 13, wherein receiving the uplink signal comprises:

receiving an uplink signal that includes multiple channels of television content.

17. The method of claim 13, wherein transmitting the downlink signal comprises:

broadcasting a downlink signal within a frequency range between 3.7 and 4.2 Gigahertz, wherein the downlink signal includes multiple channels of television content.

18. The method of claim 13, further comprising:

determining whether the satellite is located within the active orbit segment; and

when the satellite is located within the active orbit segment, transmitting the downlink signal; and

when the satellite is not located within the active orbit segment, avoiding transmitting the downlink signal.