Method and apparatus for spacecraft amplification of multi-channel signals

• US 6,173,155 B1
• Filed: 09/25/1998
• Issued: 01/09/2001
• Est. Priority Date: 10/17/1997
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Norin, John L.
• Primary Examiner(s): Hunter, Daniel S.
• Assistant Examiner(s): Gantt, Alan T.
• Application Number:
  US09/160,601
• Time in Patent Office: 837 Days
• Field of Search: 455/12.1, 455/13.1, 455/427, 455/428, 455/429, 455/69, 455/115, 455/16, 455/19, 455/20, 455/22, 375/296
• US Class Current: 455/12.1
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays

Abstract

The number of high power amplifiers required for multi-channel satellite communications is reduced by a high power amplification of selected sets of signals in respective common amplifiers, with each set of combined signals consisting of channels whose frequency bands are mutually discrete and sufficiently separated in frequency that their third order intermodulation products do not substantially overlap in frequency with any of the channels in the same set. The signals can be separated out again after amplification and transmitted as downlink signals, either individually from a dedicated downlink antenna or in combination with other channels in a common downlink antenna.

Claims

1. A method of amplifying signals for spacecraft broadcast from a plurality of input signals within different respective frequency bands, comprising:

selecting a first set of said input signals whose frequency bands are mutually discrete and sufficiently separated in frequency that their third order intermodulation products do not substantially overlap in frequency with any of the other input signals in said first set, and

amplifying the selected set of signals with a first common amplifier.

2. The method of claim 1, wherein said selected set of signals are combined prior to amplification, and the combined signal is amplified by said common amplifier.

3. The method of claim 2, further comprising the step of separating the selected set of signals from each other after amplification.

4. The method of claim 3, further comprising the steps of:

selecting at least one additional set of said input signals whose frequency bands are mutually discrete and sufficiently separate in frequency that their third order intermodulation products do not substantially overlap in frequency with any of the other input signals in the same set,

amplifying each additional set of signals with a respective common amplifier different from said first common amplifier, and

separating the signals within each additional set from each other after amplification.

5. The method of claim 4, further comprising the step of combining at least some of said separated and amplified signals.

6. The method of claim 5, wherein the combined amplified signals are combined in sets different from said sets of input signals.

7. The method of claim 4, wherein each input signal is included in no more than one of said input signal sets.

8. The method of claim 4, wherein said first set of signals have a common polarization, and at least one of said additional set of signals have a polarization opposite to said first set.

9. The method of claim 8, wherein said first and opposite polarization sets of signals have common frequency bands.

10. The method of claim 3, further comprising the step of broadcasting said separated and amplified signals from a satellite.

11. The method of claim 10, further comprising the step of combining at least some of said separated and amplified signals prior to broadcast from said satellite.

12. The method of claim 10, further comprising the step of transmitting said input signals to said satellite from a ground station.

13. The method of claim 2, wherein said first set of input signals are linearized prior to amplification.

14. The method of claim 2, wherein said first set of input signals are automatic level controlled prior to amplification.

15. The method of claim 14, wherein said first set of input signals are linearized after being automatic level controlled but prior to amplification.

16. The method of claim 14, wherein said first set of input signals are automatic level controlled prior to being combined with each other.

17. The method of claim 14, wherein said first set of input signals are automatic level controlled after being combined with each other.

18. The method of claim 2, wherein said amplifier has a rated power capacity greater than the sum of the signal powers for said first set of signals after amplification.

19. The method of claim 2, further comprising the step of amplifying at least one other of said input signals with a separate respective amplifier.

20. A spacecraft communications signal amplification system for amplifying signals from a plurality of input communication signals within different respective frequency bands, comprising:

a signal combiner connected to combine a first set of said input signals whose frequency bands are mutually discrete and sufficiently separated that their third order intermodulation products do not substantially overlap in frequency with any of the other signals in said first set, and

a first common amplifier connected to amplify the combined first set of input signals.

21. The signal amplification system of claim 20, further comprising a signal separator connected to separate said first set of signals from each other after amplification by said common amplifier.

22. The signal amplification system of claim 21, further comprising:

at least one additional signal combiner connected to combine at least one additional set of said input signals whose frequency bands are mutually discrete and sufficiently separate in frequency that their third order intermodulation products do not substantially overlap in frequency with any of the other input signals in the same set,

a respective additional common amplifier for each of said additional signal sets, connected to amplify the combined signal from its respective additional signal combiner, and

a respective additional signal separator for each of said additional signal sets connected to separate the signals within its respective set from each other after amplification.

23. The signal amplification system of claim 22, further comprising at least one output signal combiner connected to combine at least some of said separated and amplified signals.

24. The signal amplification system of claim 23, at least some of said output signal combiners connected to combine their respective separated and amplified signals into sets different from said sets of input signals.

25. The signal amplification system of claim 22, wherein said signal combiners are connected so that no input signal is connected to more than one of said signal combiners.

26. The signal amplification system of claim 22, wherein at least one of said signal combiners is connected to combine a respective set of input signals having a common first polarization, and at least one other of said signal combiners is connected to combine a respective set of opposite polarity input signals.

27. The signal amplification system of claim 26, wherein at least one signal combiner for said first polarization input signals and at least one signal combiner for said opposite polarization input signals are connected to combine respective sets of input signals having common frequency bands.

28. The signal amplification system of claim 21, further comprising at least one output signal combiner connected to combine at least some of said separated and amplified signals.

29. The signal amplification system of claim 20, further comprising at least one additional amplifier connected to amplify a single respective one of said input signals uncombined with any other input signal.

30. The signal amplification system of claim 20, further comprising linearizers connected to linearize the input signals in said first set prior to amplification.

31. The signal amplification system of claim 20, further comprising automatic level controllers connected to control the levels of the input signals in said first set prior to amplification by said common amplifier.

32. The signal amplification system of claim 31, further comprising linearizers connected to linearize the input signals in said first set after said automatic level controllers but prior to amplification.

33. A communications satellite, comprising:

a satellite body,

an uplink antenna system on said satellite body for receiving a multi-channel uplink signal,

a plurality of channel filters connected to separate a signal received by said uplink antenna system into a plurality of channel signals with mutually discrete frequency bands,

a signal combiner connected to combine a first set of said channel signals whose frequency bands are sufficiently separated in frequency that their third order intermodulation products do not substantially overlap in frequency with any of the other channel signals in said first set,

a first common amplifier connected to amplify the combined signal, and

a downlink antenna system connected to transmit said first set of channel signals after amplification by said common amplifier.

34. The communications satellite of claim 33, further comprising a signal separator connected to separate said first set of channel signals from each other after amplification by said common amplifier and prior to transmission by said downlink antenna system.

35. The communications satellite of claim 34, further comprising:

at least one additional signal combiner connected to combine at least one additional set of channel signals, each additional set consisting of at least two of said channel signals whose frequency bands are sufficiently separate in frequency that their third order intermodulation products do not substantially overlap in frequency with any of the other channel signals in the same set,

a respective additional common amplifier for each of said additional channel signal sets, connected to amplify the combined signal from its respective additional signal combiner, and

a respective additional signal separator for each of said additional signal sets connected to separate the channel signals in its respective set from each other after amplification,

said downlink antenna system connected to transmit each of said additional sets of channel signals after amplification and signal separation.

36. The communications satellite of claim 35, further comprising at least one output signal combiner connected to combine at least some of said separated and amplified channel signals prior to transmission by said downlink antenna system.

37. The communications satellite of claim 36, at least one of said output signal combiners connected to combine its respective separated and amplified signals into a set different from said channel signal sets prior to amplification.

38. The communications satellite of claim 35, wherein said signal combiners are connected so that no channel signal is connected to more than one of said signal combiners.

39. The communications satellite of claim 35, wherein at least one of said signal combiners is connected to combine a respective set of channel signals having a common first polarization, and at least one other of said signal combiners is connected to combine a respective set of opposite polarity channel signals.

40. The communications satellite of claim 39, wherein at least one signal combiner for said first polarization channel signals and at least one signal combiner for said opposite polarization channel signals are connected to combine respective sets of channel signals having common frequency bands.

41. The communications satellite of claim 34, further comprising at least one output signal combiner connected to combine at least some of said separated and amplified channel signals prior to transmission by said downlink antenna system.

42. The communications satellite of claim 33, further comprising automatic level controllers connected to control the level of said channel signal set prior to amplification by said common amplifier.

43. The communications satellite of claim 33, further comprising frequency converters for converting the frequencies of said channel signals from uplink to downlink frequencies.

44. The communications satellite of claim 43, wherein said frequency converters are connected between said channel filters and said signal combiner.

45. The communications satellite of claim 33, wherein said downlink antenna system is configured to broadcast signals at broadcast satellite service (BSS) and fixed satellite service (FSS) frequencies.

46. The communications satellite of claim 33, further comprising at least one additional amplifier connected to amplify a single respective one of said channel signals uncombined with any other channel signal for transmission by said downlink antenna system.