Continuous phase modulation system and method with added orthogonal signals

• US 20050276345A1
• Filed: 06/15/2004
• Published: 12/15/2005
• Est. Priority Date: 06/15/2004
• Status: Active Grant

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Nieto, John W., Norris, James A.
• Granted Patent: US 7,561,634 B2
• Time in Patent Office: Days
• US Class Current: 375/265
• CPC Class Codes: H04L 27/201 in which the allowed phase changes vary with time, e.g. multi-h modulation

Abstract

A system and method of the present invention forms a hybrid encoded signal. A signal generator generates a coded waveform having a trellis structure, such as a continuous phase modulated signal. A modulator is operative with the signal generator and adds at least one orthogonal or amplitude modulated waveform to a trellis structure of the coded waveform to create a non-constant envelope modulated signal that has at least one of increased bandwidth, improved bit error rate, or an increased number of bits encoded into a single symbol.

Claims

1. A system for forming an encoded signal comprising:

a signal generator for generating a coded waveform having a trellis structure; and

a modulator operative with the signal generator for adding at least one orthogonal or pseudo-orthogonal waveform to a trellis structure of the coded waveform to create a non-constant envelope modulated signal that has at least one of increased bandwidth, improved bit error rate, and increased number of bits encoded into a single symbol.

2. A system according to claim 1, wherein the modulator is operative for amplitude shaping the coded waveform with integer or non-integer frequency multiples of amplitude modulated signals.

3. A system according to claim 2, and further comprising a demodulator operative for employing a Fast Fourier Transform in branch metric computations and discriminating between amplitude modulated signals.

4. A system according to claim 2, wherein the modulator is operative for increasing the number of cycles per symbol for a pair of amplitude modulated signals.

5. A system according to claim 1, wherein the modulator is operative for increasing higher order modulation within the encoded waveform by increasing orthogonal symbols.

6. A system according to claim 1, wherein the modulator is operative for generating a symbol alphabet using a sum of orthogonal frequencies.

7. A system according to claim 6, wherein the modulator is operative for creating a multiple-ary encoded waveform using multiple-ary symbols and at least one extra-encoded amplitude modulated bit.

8. A system according to claim 7, wherein the multiple-ary encoded waveform comprises a Sin (Fs/2) amplitude shape.

9. A system according to claim 7, where the multiple-ary encoded waveform comprises a Sin (Fs) amplitude shape.

10. A system according to claim 1, wherein the modulator is operative for changing a phase offset per symbol to provide sufficient distance for a parallel path to work with a trellis structure.

11. A system according to claim 10, wherein the modulator is operative for increasing the distance between constellation points in a trellis.

12. A system according to claim 1, wherein the modulator is operative for creating higher order orthogonal signals using a sum of orthogonal signals (Sin (Fs)+Sin (2Fs)).

13. A system for forming a hybrid continuous phase modulated signal comprising:

a signal generator for generating a continuous phase modulated signal; and

a modulator operative with the signal generator for adding at least one orthogonal or pseudo-orthogonal waveform to the generated continuous phase modulated signal to create a hybrid, non-constant envelope, continuous phase modulated signal.

14. A system according to claim 13, wherein the modulator is operative for amplitude shaping the continuous phase modulated signal with integer or non-integer frequency multiples of amplitude modulated signals.

15. A system according to claim 14, and further comprising a demodulator operative for employing a Fast Fourier Transform in branch metric computations and discriminating between amplitude modulated signals.

16. A system according to claim 14, wherein the modulator is operative for increasing the number of cycles per symbol for a pair of amplitude modulated signals.

17. A system according to claim 13, wherein the modulator is operative for increasing higher order modulation within the continuous phase modulated signal by increasing orthogonal symbols.

18. A system according to claim 13, wherein the modulator is operative for generating a symbol alphabet using a sum of orthogonal frequencies.

19. A system according to claim 18, wherein the modulator is operative for creating a multiple-ary encoded waveform using multiple-ary symbols and at least one extra-encoded amplitude modulated bit.

20. A system according to claim 19, wherein the multiple-ary encoded waveform comprises a Sin (Fs/2) amplitude shape.

21. A system according to claim 19, wherein the multiple-ary waveform comprises a Sin (Fs) amplitude shape.

22. A system according to claim 13, wherein the modulator is operative for changing a phase offset per symbol to provide sufficient distance for a parallel path to work with a trellis.

23. A system according to claim 22, wherein the modulator is operative for increasing the distance between constellation points in a trellis.

24. A system according to claim 13, wherein the modulator is operative for creating higher order orthogonal signals using a sum of orthogonal signals (Sin (Fs)+Sin (2Fs)).

25. A method of forming an encoded modulated signal, which comprises:

adding at least one orthogonal or pseudo-orthogonal waveform to a trellis structure of a coded waveform to create a non-constant envelope modulated signal that has at least one of increased bandwidth, improved bit error rate, and an increased number of bits encoded into a single symbol.

26. A method according to claim 25, which further comprises amplitude shaping the coded waveform with integer frequency multiples of amplitude modulated signals.

27. A method according to claim 26, which further comprises employing a Fast Fourier Transform in branch metric computations and discriminating between amplitude modulated signals in a demodulator.

28. A method according to claim 26, which further comprises increasing the number of cycles per symbol for a pair of amplitude modulated signals.

29. A method according to claim 25, which further comprises increasing higher order modulation within the encoded waveform by increasing orthogonal symbols.

30. A method according to claim 29, which further comprises generating a symbol alphabet using a sum of orthogonal frequencies.

31. A method according to claim 30, which further comprises creating a multiple-ary encoded waveform using multiple-ary symbols and an extra-encoded amplitude modulated bit.

32. A method according to claim 31, wherein the multiple-ary encoded waveform comprises a Sin (Fs) amplitude shape.

33. A method according to claim 31, wherein the multiple-ary encoded waveform comprises a Sin (Fs) amplitude shape.

34. A method according to claim 25, which further comprises changing a phase offset per symbol to provide sufficient distance for a parallel path to work with a trellis.

35. A method according to claim 25, which further comprises increasing the distance between constellation points in a trellis.

36. A method according to claim 25, which further comprises creating higher order orthogonal signals using a sum of orthogonal signals (Sin (Fs)+Sin (2Fs)).

37. A method of forming a hybrid continuous phase modulated signal, which comprises:

adding at least one orthogonal or pseudo-orthogonal waveform to a continuous phase modulated signal to create a non-constant envelope continuous phase modulated signal.

38. A method according to claim 37, which further comprises amplitude shaping the continuous phase modulated signal with integer frequency multiples of amplitude modulated signals.

39. A method according to claim 38, which further comprises employing a Fast Fourier Transform in branch metric computations and discriminating between amplitude modulated signals in a demodulator.

40. A method according to claim 38, which further comprises increasing the number of cycles per symbol for a pair of amplitude modulated signals.

41. A method according to claim 37, which further comprises increasing higher order modulation within the continuous phase modulated signal by increasing orthogonal symbols.

42. A method according to claim 41, which further comprises generating a symbol alphabet using a sum of orthogonal frequencies.

43. A method according to claim 42, which further comprises creating a multiple-ary continuous phase modulated waveform using multiple-ary symbols and an extra-encoded amplitude modulated bit.

44. A method according to claim 43, wherein the multiple-ary continuous phase modulated waveform comprises a Sin (Fs/2) amplitude shape.

45. A method according to claim 43, where the multiple-ary continuous phase modulated waveform comprises a Sin (Fs) amplitude shape.

46. A method according to claim 37, wherein said continuous phase modulated signal comprises a trellis modulated signal.

47. A method according to claim 46, which further comprises changing a phase offset per symbol to provide sufficient distance for a parallel path to work with a continuous phase modulated trellis.

48. A method according to claim 46, which further comprises increasing the distance between constellation points in the trellis.

49. A method according to claim 37, which further comprises creating higher order orthogonal signals using a sum of orthogonal signals (Sin (Fs)+Sin (2Fs)).

50. A method of forming a hybrid continuous phase modulated signal, which comprises:

adding at least one orthogonal or pseudo-orthogonal waveform to a continuous phase modulated signal; and

sine amplitude shaping the signal to create a non-constant envelope continuous phase modulated signal.

51. A method according to claim 50, which further comprises replacing a constant radius continuous phase modulated signal shape with a one-half sine wave amplitude.

52. A method according to claim 50, which further comprises using a radius that is equal to a constant minus the amplitude shape for clockwise symbols.

53. A method according to claim 50, which further comprises using a radius that is equal to a constant plus an amplitude shape for counter-clockwise symbols.

54. A method according to claim 50, which further comprises amplitude shaping the continuous phase modulated signal with integer frequency multiples of amplitude modulated signals.

55. A method according to claim 54, which further comprises employing a Fast Fourier Transform in branch metrics and discriminating between amplitude modulated signals in a demodulator.

56. A method according to claim 50, which further comprises increasing the number of cycles per symbol for a pair of amplitude modulated signals.

57. A method according to claim 50, which further comprises increasing higher order modulation within the continuous phase modulated signal by increasing orthogonal symbols.

58. A method according to claim 57, which further comprises generating a symbol alphabet using a sum of orthogonal frequencies.

59. A method according to claim 58, which further comprises creating a multiple-ary continuous phase modulated waveform using multiple-ary symbols and an extra-encoded amplitude modulated bit.

60. A method according to claim 59, wherein the multiple-ary continuous phase modulated waveform comprises a Sin (Fs/2) amplitude shape.

61. A method according to claim 59, wherein the multiple-ary continuous phase modulated waveform comprises Sin (Fs) amplitude shape.

62. A method according to claim 57, wherein said continuous phase modulated signal comprises a trellis modulated signal.

63. A method according to claim 62, which further comprises changing a phase offset per symbol to provide sufficient distance for a parallel path to work with a continuous phase modulated trellis.

64. A method according to claim 62, which further comprises increasing the distance between constellation points in the trellis.

65. A method according to claim 57, which further comprises creating higher order orthogonal signals using a sum of orthogonal signals (Sin (Fs)+Sin (2Fs)).