Common direct broadcasting service system

• US 5,978,652 A
• Filed: 01/10/1997
• Issued: 11/02/1999
• Est. Priority Date: 01/10/1997
• Status: Expired due to Fees

• Current Assignee: Space Systems/Loral Incorporated (Loral Space and Communications Incorporated)
• Original Assignee: Space Systems/Loral Incorporated (Loral Space and Communications Incorporated)
• Inventors: Burr, Douglas, Ellington, Troy
• Primary Examiner(s): Vo, Nguyen
• Assistant Examiner(s): BANKS HAROLD, MARSHA DENISE
• Application Number:
  US08/781,395
• Time in Patent Office: 1,026 Days
• Field of Search: 455/12.1, 455/13.1, 455/13.3, 455/20, 455/3.2, 455/6.3, 455/6.2, 342/363, 342/365, 348/8
• 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

Abstract

The invention relates to a Common Direct Broadcasting Service (CDBS) system for a communications spacecraft. The CDBS system comprises N uplink antennas for receiving uplinks from terrestrial transmitting stations. Each uplink includes left-hand circular polarized (LHCP) signals and/or right-hand circular polarized (RHCP) signals. The LHCP signals and the RHCP signals have frequencies within predetermined channels of a first and/or second predefined frequency band. The CDBS system also comprises means for separating the LHCP signals of the uplinks received by each uplink antenna from the RHCP signals of the uplinks received by each uplink antenna. The CDBS system further comprises a plurality of receivers for converting the separated LHCP signals and RHCP signals of the uplinks to first signals and second signals, respectively, of the uplinks. The first and second signals have frequencies within channels of a third and/or fourth predefined frequency band. The CDBS system also includes means for selecting a predetermined number of the first and second signals of the uplinks, and means for down-selecting signals of the predetermined number of the first and second signals having frequencies within selected ones of the channels of the third and/or fourth predefined frequency bands. The CDBS system further comprises a plurality of downlink antennas for downlinking signals down-selected by the down-selecting means from the communications spacecraft to selected ones of the plurality of terrestrial receiving stations.

Claims

1. A Common Direct Broadcasting Service (CDBS) system for a communications spacecraft, the CDBS system comprising:

N uplink antennas, each of said N uplink antennas for receiving uplinks from terrestrial transmitting stations, each of said uplinks including at least one of left-hand circular polarized (LHCP) signals and right-hand circular polarized (RHCP) signals, individual ones of said LHCP signals and said RHCP signals having frequencies within predetermined channels of at least one of a first predefined frequency band and a second predefined frequency band;

means for separating the LHCP signals of the uplinks received by each of said N uplink antennas from the RHCP signals of the uplinks received by each of said N uplink antennas;

means for converting the separated LHCP signals and RHCP signals of the uplinks received by each of said N uplink antennas to first signals and second signals, respectively, of the uplinks, said first and second signals having frequencies within channels of at least one of a third predefined frequency band and a fourth predefined frequency band;

means for selecting a predetermined number of the first signals and second signals of the uplinks;

means for down-selecting signals of the predetermined number of the first and second signals having frequencies within selected ones of the channels of the at least one of the third and fourth predefined frequency bands;

means for amplifying signals down-selected by said down-selecting means and for outputting resultant amplified signals; and

a plurality of downlink antennas for downlinking signals output by said amplifying means from the communications spacecraft to selected ones of the plurality of terrestrial receiving stations.

2. A CDBS system as set forth in claim 1, wherein said first and third predefined frequency bands are allocated for civilian users, and wherein the second and fourth predefined frequency bands are allocated for military users.

3. A CDBS system as set forth in claim 1, wherein said selecting means and said down-selecting means perform in accordance with information supplied to the communications spacecraft from a terrestrial network control station.

4. A method as set forth in claim 1, wherein said amplifying means comprises a plurality of amplification sections, each of said amplification sections including:

a plurality of communications paths, each individual one of said communications paths including at least one traveling wave tube amplifier (TWTA) for amplifying signals applied to said individual communications path and outputting corresponding amplified signals from said individual communications path;

an input redundancy switching ring, said input redundancy switching ring being controllable for applying selected ones of said signals down-linked by said downlinking means to selected ones of said plurality of communications paths; and

an output redundancy switching ring, said output redundancy switching ring being controllable for outputting amplified signals output by selected ones of said plurality of communications paths.

5. A CDBS system as set forth in claim 1, wherein each of the first, second, third, and fourth predefined frequency bands includes at least twelve channels.

6. A CDBS system as set forth in claim 1, wherein the first predefined frequency band extends between approximately 29.5 GHz and 30.0 GHz on the frequency spectrum, and wherein the second predefined frequency band extends between approximately 30.0 GHz and 30.5 GHz on the frequency spectrum.

7. A CDBS system as set forth in claim 1, wherein the third predefined frequency band extends between approximately 19.7 GHz and 20.2 GHz on the frequency spectrum, and wherein the fourth predefined frequency band extends between approximately 20.2 GHz and 20.7 GHz on the frequency spectrum.

8. A CDBS system as set forth in claim 1, wherein center frequencies of the channels of individual ones of the first, second, third, and fourth predefined frequency bands are separated by approximately 40 MHz.

9. A CDBS system as set forth in claim 1, wherein the channels of individual ones of the first, second, third, and fourth predefined frequency bands have a bandwidth of about 36 MHz.

10. A method for relaying signals between individual ones of a plurality of terrestrial transmitting stations and selected individual ones of a plurality of terrestrial receiving stations via a communications spacecraft, the method comprising the steps of:

providing uplinks from the plurality of terrestrial stations to said communications spacecraft, each of said uplinks including at least one of left-hand circular polarized (LHCP) signals and right-hand circular polarized (RHCP) signals, individual ones of said LHCP signals and said RHCP signals having frequencies within predetermined channels of at least one of a first predefined frequency band and a second predefined frequency band;

separating the LHCP signals of the uplinks from the RHCP signals of the uplinks;

converting the separated LHCP signals and RHCP signals of the uplinks to first signals and second signals, respectively, of the uplinks, said first and second signals having frequencies within channels of at least one of a third predefined frequency band and a fourth predefined frequency band;

selecting a predetermined number of the first signals and second signals of the uplinks;

down-selecting selected ones of the predetermined number of the first and second signals having frequencies within selected ones of the channels of the at least one of the third and fourth predefined frequency bands; and

downlinking down-selected ones of the signals of the predetermined number of first and second signals from the communications spacecraft to selected ones of the plurality of terrestrial receiving stations.

11. A method as set forth in claim 10, wherein the first and third predefined frequency bands are allocated for civilian users, and wherein the second and fourth predefined frequency bands are allocated for military users.

12. A method as set forth in claim 10, wherein the steps of selecting and down-selecting are performed in accordance with information supplied to the communications spacecraft from a terrestrial network control station.

13. A method as set forth in claim 10, wherein, before the step of downlinking is performed, a step is performed of amplifying the down-selected signals.

14. A method as set forth in claim 13, wherein the step of amplifying includes the steps of:

splitting each of the down-selected signals into two corresponding signal portions;

amplifying each of the two corresponding signal portions of each down-selected signal to produce amplified signal portions; and

combining the amplified signal portions of each down-selected signal; and

wherein the step of downlinking is performed by downlinking combined ones of the amplified signal portions of each down-selected signal from the communications spacecraft to the selected ones of the plurality of terrestrial receiving stations.

15. A method as set forth in claim 10, wherein each of the first, second, third, and fourth predefined frequency bands includes at least twelve channels.

16. A method as set forth in claim 10, wherein the first predefined frequency band extends between approximately 29.5 GHz and 30.0 GHz on the frequency spectrum, and wherein the second predefined frequency band extends between approximately 30.0 GHz and 30.5 GHz on the frequency spectrum.

17. A method as set forth in claim 10, wherein the third predefined frequency band extends between approximately 19.7 GHz and 20.2 GHz on the frequency spectrum, and wherein the fourth predefined frequency band extends between approximately 20.2 GHz and 20.7 GHz on the frequency spectrum.

18. A method as set forth in claim 10, wherein center frequencies of the channels of individual ones of the first, second, third, and fourth predefined frequency bands are separated by approximately 40 MHz.

19. A method as set forth in claim 10, wherein the channels of individual ones of the first, second, third, and fourth predefined frequency bands have a bandwidth of about 36 MHz.

20. A Common Direct Broadcast Service (CDBS) system for a spacecraft, comprising:

N uplink antennas, each of said N uplink antennas for receiving uplinks from terrestrial transmitting stations, each of said uplinks including at least one of left-hand circular polarized (LHCP) signals and right-hand circular polarized (RHCP) signals, individual ones of said LHCP signals and said RHCP signals having frequencies within predetermined channels of at least one of a first predefined frequency band and a second predefined frequency band;

N separating means, individual ones of said N separating means for separating said LHCP signals received by respective ones of said uplink antennas from said RHCP signals received by said respective ones of said uplink antennas, and for outputting separated LHCP and RHCP signals;

a first group of N receivers, individual ones of said first group of N receivers for converting the separated LHCP and RHCP signals output by a first one of said N separating means to first converted signals having frequencies within channels of at least one of a third and a fourth predefined frequency band;

a second group of N receivers, individual ones of said second group of N receivers for converting the separated LHCP and RHCP signals output by a second one of said N separating means to second converted signals having frequencies within channels of at least one of said third and fourth predefined frequency bands;

means for splitting said first converted signals into 2N corresponding first converted signals, and for splitting each of said second converted signals into 2N corresponding second converted signals;

a plurality of switching means, individual ones of said plurality of switching means being controllable for selecting one of said 2N corresponding first converted signals and said 2N corresponding second converted signals, and for providing the selected one of said 2N corresponding first converted signals and said 2N corresponding second converted signals to a respective output;

a plurality of downlink antennas, each of said downlink antennas for downlinking signals applied thereto to a respective pre-selected terrestrial region; and

means, being controllable, for selecting at least one of said signals output by individual ones of said plurality of switching means, and for providing an output to selected ones of said plurality of downlink antennas.

21. A Common Direct Broadcasting Service (CDBS) system for a communications spacecraft, the CDBS system comprising:

a plurality of uplink antennas, each of said uplink antennas for receiving uplinks from terrestrial transmitting stations, each of said uplinks including at least one of left-hand circular polarized (LHCP) signals and right-hand circular polarized (RHCP) signals, said LHCP signals and said RHCP signals having frequencies within predetermined ones of N channels of a first predefined frequency band and N channels of a second predefined frequency band;

means for converting the LHCP signals and the RHCP signals of said uplinks received by each of said uplink antennas to first signals and second signals, respectively, of the uplinks, said first and second signals having frequencies within predetermined ones of N channels of a third predefined frequency band and N channels of a fourth predefined frequency band;

means for selecting N of the first signals and the second signals;

means for down-selecting N/2 of the N first and second signals selected by said selecting means having frequencies within selected ones of the channels of the third and fourth predefined frequency bands;

plurality of downlink antennas for downlinking signals down-selected by said down-selecting means from the communications spacecraft to selected ones of the plurality of terrestrial receiving stations.

22. A CDBS system as set forth in claim 21, wherein said first and third predefined frequency bands are allocated for civilian users, and wherein the second and fourth predefined frequency bands are allocated for military users.