Simplified high frequency tuner and tuning method

• US 8,005,450 B2
• Filed: 06/12/2009
• Issued: 08/23/2011
• Est. Priority Date: 09/13/1996
• Status: Expired due to Fees

• Current Assignee: Washington Research Foundation (University of Washington)
• Original Assignee: University of Washington
• Inventors: Suominen, Edwin A.
• Primary Examiner(s): Jackson; Blane J
• Application Number:
  US12/484,018
• Publication Number:
  US 20090253394A1
• Time in Patent Office: 802 Days
• Field of Search: 455/255, 455/256, 455/257, 455/258, 455/266, 455/296, 455/323, 455/324, 455/208, 455/209, 455/254, 455/302, 455/307, 455/313, 455/334
• US Class Current: 455/258
• CPC Class Codes: H03D 3/007 by converting the oscillations into two quadrature related signals H03D3/245 takes precedence
• CPC Class Codes: H03D 3/009 Compensating quadrature phase or amplitude imbalances
• CPC Class Codes: H03D 7/165 at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature combined with amplitude demodulation H03D1/2245, combined with angle demodulation H03D3/007; N-path filters H03H19/002
• CPC Class Codes: H04B 1/06 Receivers
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04B 1/16 Circuits
• CPC Class Codes: H04B 1/26 for superheterodyne receivers multiple frequency-changing H03D7/16
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22
• CPC Class Codes: H04L 25/067 providing soft decisions, i.e. decisions together with an estimate of reliability H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178

Abstract

A disclosed method tunes a signal from a channelized spectrum having a predetermined channel spacing. A signal of interest having a predetermined maximum bandwidth is mixed with a local oscillator signal, which has a frequency that is an integer multiple of the channel spacing or one-half of a channel spacing displaced from an integer multiple of the channel spacing. The local oscillator signal is selected to frequency translate the signal of interest to within a near-baseband passband whose lower edge is spaced from DC by at least about the maximum bandwidth of the signal of interest. Problems associated with 1/f noise, DC offsets, and self-mixing products are avoided or substantially diminished. Other methods and systems are also disclosed.

Claims

1. A tuning method comprising:

(a) mixing a channel of interest from a channelized spectrum having a predetermined channel spacing with a first local oscillator signal;

(b) wherein the first local oscillator signal has a first frequency that is (1) one-half of a channel spacing displaced from an integer multiple of the channel spacing, and (2) selected to frequency translate the channel of interest to within a passband whose lower edge is spaced from DC by about the channel spacing and whose width is about the channel spacing.

2. The method of claim 1 wherein the channel of interest has a predetermined maximum bandwidth less than the channel spacing.

3. The method of claim 1 further comprising course-tuning the local oscillator signal by one local oscillator step from the first frequency to a second frequency an integral number of channel spacings from the first frequency.

4. The method of claim 3 wherein the second frequency is two channel spacings from the first frequency.

5. Apparatus for tuning, from a channelized spectrum having a predetermined channel spacing, a channel of interest, the apparatus comprising:

(a) a local oscillator configured to generate a local oscillator signal at a first frequency that is one half of the channel spacing displaced from an integer multiple of the channel spacing; and

(b) a mixer responsive to the local oscillator signal and the channel of interest, wherein the mixer frequency translates the channel of interest;

(c) wherein the frequency-translated channel of interest falls within a passband that is about a channel spacing wide and that is spaced from DC by a frequency offset of about the channel spacing.

6. The apparatus of claim 5 wherein the channel of interest has a predetermined maximum bandwidth less than the channel spacing.

7. A tuning method comprising:

(a) mixing a channel of interest from a channelized spectrum with a first local oscillator signal; and

(b) filtering the mixed signal to define a near-baseband passband that is (1) sized to fit one channel spacing, and (2) has a lower edge spaced from DC by about an integer multiple of the channel spacing or a half-channel-spacing displaced from about an integer multiple of the channel spacing.

8. The method of claim 7 wherein the passband is situated near baseband but sufficiently far from DC to substantially avoid 1/f noise.

9. The method of claim 7 wherein the lower edge of the near-baseband passband is spaced from DC by about twice the channel spacing.

10. The method of claim 7 further comprising repeating parts (a) and (b) for a plurality of different local oscillator frequencies.

11. The method of claim 7 wherein the lower edge of the near-baseband passband is spaced from DC by about the channel spacing.

12. The method of claim 7 wherein the lower edge of the near-baseband passband is spaced from DC by about 1.5 times the channel spacing.

13. The method of claim 7 wherein the lower edge of the near-baseband passband is spaced from DC by about an integer multiple of the channel spacing.

14. The method of claim 7 wherein the lower edge of the near-baseband passband is spaced from DC by an integer multiple of the channel spacing.

15. The method of claim 7 wherein the lower edge of the near-baseband passband is spaced from DC by a half-channel-spacing displaced from about an integer multiple of the channel spacing.

16. The method of claim 7 wherein the lower edge of the near-baseband passband is spaced from DC by a half-channel-spacing displaced from an integer multiple of the channel spacing.

17. The method of claim 7 wherein mixing a channel of interest with a first local oscillator signal comprises applying one local oscillator frequency of a set of local oscillator frequencies.

18. The method of claim 7 wherein the lower edge of the near-baseband passband is spaced from DC by about 2.5 times the channel spacing.

19. A method for tuning a channel of interest, comprising:

(a) receiving a channel of interest from a channelized spectrum having a predetermined channel spacing, wherein the channel of interest has a predetermined maximum bandwidth less than the channel spacing;

(b) producing I and Q signals in approximate quadrature relation by mixing the channel of interest with an approximately quadrature local oscillator signal having a first frequency that is one-half of a channel spacing displaced from an integer multiple of the channel spacing;

(c) defining a near-baseband passband whose lower edge is spaced from DC by an integer multiple of the channel spacing, by passband filtering the I and Q signals.

20. The method of claim 19 wherein the lower edge of the near-baseband passband is spaced from DC by an integer multiple of the channel spacing.

21. The method of claim 19 wherein the lower edge of the near-baseband passband is spaced from DC by about the channel spacing.

22. The method of claim 19 wherein the lower edge of the near-baseband passband is spaced from DC by about twice the channel spacing.

23. A method for tuning a channel from a channelized spectrum having predetermined channel spacing, the method comprising:

(a) mixing a channel of interest with a first local oscillator signal;

(b) wherein the first local oscillator signal has a first frequency that (1) is an integer multiple of the channel spacing and (2) is selected to frequency translate the channel of interest to within a near-baseband passband whose lower edge is spaced from DC by at least about the channel spacing.

24. The method of claim 23 further comprising spacing the near-baseband passband'"'"'s lower edge from DC by about 1.5 times the channel spacing.

25. The method of claim 23 further comprising coarse-tuning the local oscillator signal by one local oscillator step from the first frequency to a second frequency an integral number of channel spacings from the first frequency.

26. The method of claim 25 wherein the second frequency is two channel spacings from the first frequency.

27. The method of claim 23 wherein the spacing of the lower edge of the near-baseband passband from DC is greater than the channel spacing.

28. The method of claim 27 wherein the spacing of the lower edge of the near-baseband passband from DC is about twice the channel spacing.

29. Apparatus for tuning, from a channelized spectrum having a predetermined channel spacing, a channel of interest, the apparatus comprising:

(a) a local oscillator configured to generate a local oscillator signal at a frequency that is an integer multiple of the channel spacing; and

(b) a mixer responsive to the local oscillator signal and the channel of interest, wherein the mixer frequency translates the channel of interest;

(c) wherein the frequency-translated channel of interest falls within a near-baseband passband spaced from DC by a frequency offset of at least about the channel spacing.

30. The apparatus of claim 29 wherein the spacing of the lower edge of the near-baseband passband from DC is greater than the channel spacing.

31. The apparatus of claim 30 wherein the spacing of the lower edge of the near-baseband passband from DC is about 1.5 times the channel spacing.

32. The apparatus of claim 30 wherein the spacing of the lower edge of the near-baseband passband from DC is about twice the channel spacing.

33. The apparatus of claim 30 wherein the spacing of the lower edge of the near-baseband passband from DC is about 2.5 times the channel spacing.

34. The apparatus of claim 29 wherein the local oscillator is coarse-tunable to generate a frequency that is two channel spacings away from the frequency of the desired channel to be tuned.

35. The apparatus of claim 29 further comprising:

(a) a second local oscillator configured to generate a second local oscillator signal having the frequency of, and approximately in quadrature with the first local oscillator signal; and

(b) a second mixer responsive to the second local oscillator signal; and

the channel of interest, wherein;

(1) the channel of interest lies within one of an upper high frequency spectrum of interest and a lower high frequency spectrum of interest; and

(2) the apparatus provides spectrum coverage within one of the high frequency spectra of interest and not the other.

36. A tuning method comprising:

(a) defining a passband that is approximately a channel spacing wide, the lower edge of which is situated near baseband but spaced from DC by approximately an integer multiple of channel spacing or approximately a half-channel displaced from an integer multiple of channel spacing; and

(b) frequency translating, with one local oscillator frequency of a set of local oscillator frequencies, a channel of interest from a channelized spectrum having a predetermined channel spacing, such that the center frequency of the frequency-translated channel of interest falls within the passband.

37. The method of claim 36 wherein defining a passband comprises defining a passband that is wider than a channel spacing by a frequency adjustment.

38. The method of claim 37 wherein the frequency adjustment is predetermined.

39. The method of claim 37 wherein the frequency adjustment is static.

40. The method of claim 37 wherein defining a passband comprises extending the upper and lower edges of the passband by frequency adjustments.

41. The method of claim 40 wherein the frequency adjustments are not equal.

42. The method of claim 36 wherein defining the passband comprises defining a passband whose center frequency has a spacing from DC that differs from an integer multiple of channel spacing or a half-channel displaced from an integer multiple of channel spacing by an amount determined by a frequency adjustment.

43. The method of claim 42 wherein the frequency adjustment is about half of the channel spacing.

44. The method of claim 36 wherein the lower edge of the near-baseband passband is spaced from DC by about the channel spacing.

45. The method of claim 36 wherein the lower edge of the near-baseband passband is spaced from DC by about 1.5 times the channel spacing.

46. The method of claim 36 wherein the lower edge of the near-baseband passband is spaced from DC by about twice the channel spacing.

47. The method of claim 36 wherein the lower edge of the near-baseband passband is spaced from DC by about 2.5 times the channel spacing.

48. The method of claim 36 wherein frequency translating the channel of interest comprises producing I and Q signals in approximate quadrature relation by mixing the channel of interest with an approximately quadrature local oscillator signal having the local oscillator frequency.

49. A tuning method comprising:

(a) defining a passband that is approximately a channel spacing wide, the lower edge of which is near baseband but spaced from DC by at least about a channel spacing; and

(b) frequency translating, with one local oscillator frequency of a set of local oscillator frequencies, a channel of interest from a channelized spectrum having a predetermined channel spacing, such that the center frequency of the frequency-translated channel of interest falls within the passband.

50. The method of claim 49 wherein defining a passband comprises defining a passband that is wider than a channel spacing by a frequency adjustment.

51. The method of claim 50 wherein the frequency adjustment is predetermined.

52. The method of claim 50 wherein the frequency adjustment is static.

53. The method of claim 50 wherein defining a passband comprises adjusting the upper and lower edges of the passband by frequency adjustments.

54. The method of claim 51 wherein the frequency adjustments are not equal.

55. The method of claim 53 wherein defining the passband comprises defining a passband whose center frequency has a spacing from DC that differs from an integer multiple of channel spacing or a half-channel displaced from an integer multiple of channel spacing by a frequency adjustment.

56. The method of claim 49 wherein the frequency adjustment is about half of the channel spacing.

57. The method of claim 55 wherein the lower edge of the passband is spaced from DC by about the channel spacing.

58. The method of claim 49 wherein the lower edge of the passband is spaced from DC by about 1.5 times the channel spacing.

59. The method of claim 49 wherein the lower edge of the passband is spaced from DC by about twice the channel spacing.

60. The method of claim 49 wherein the lower edge of the passband is spaced from DC by about 2.5 times the channel spacing.

61. The method of claim 49 wherein frequency translating the channel of interest comprises producing I and Q signals in approximate quadrature relation by mixing the channel of interest with an approximately quadrature local oscillator signal having the local oscillator frequency.

62. A method for tuning a signal from a channelized spectrum having a predetermined channel spacing, the method comprising:

(a) mixing a signal of interest having a predetermined maximum bandwidth with a first local oscillator signal; and

(b) mixing the signal of interest with a second local oscillator signal having the first frequency and being approximately in quadrature with the first local oscillator signal;

(c) wherein the first local oscillator signal has a frequency that is (1) one-half of a channel spacing displaced from an integer multiple of the channel spacing and (2) is selected to frequency translate the signal of interest to within a near-baseband passband whose lower edge is spaced from DC by at least about the maximum bandwidth of the signal of interest; and

(d) the near-baseband passband is defined with reference to a lower frequency F1 and an upper frequency F2, wherein F1=F2−

F1;

whereby problems associated with 1/f noise, DC offsets, and self-mixing products are avoided or substantially diminished.

63. The method of claim 62 wherein:

(a) the signal of interest lies within one of an upper high frequency spectrum of interest and a lower high frequency spectrum of interest; and

(b) the method further comprises providing spectrum coverage within one of the high frequency spectra of interest and not the other.

64. Apparatus for tuning, from a channelized spectrum having a predetermined channel spacing, a signal of interest having a predetermined maximum bandwidth, the apparatus comprising:

(a) a local oscillator configured to generate a local oscillator signal at a frequency that is one-half of a channel spacing displaced from an integer multiple of the channel spacing;

(b) a mixer responsive to the local oscillator signal and the signal of interest, wherein the mixer frequency translates the signal of interest;

(c) a second local oscillator configured to generate a second local oscillator signal having the first frequency and being approximately in quadrature with the first local oscillator signal; and

(d) a second mixer responsive to the second local oscillator signal and the signal of interest;

(e) the frequency-translated signal of interest falls within a near-baseband passband spaced from DC by a frequency offset of at least about the maximum bandwidth of the signal of interest; and

(f) the near-baseband passband is defined with reference to a lower frequency F1 and an upper frequency F2, wherein F1=F2−

F1;

whereby problems associated with 1/f noise, DC offsets, and self-mixing products are avoided or substantially diminished.

65. The apparatus of claim 64 wherein:

(a) the signal of interest lies within one of an upper high frequency spectrum of interest and a lower high frequency spectrum of interest; and

(b) the apparatus provides spectrum coverage within one of the high frequency spectra of interest and not the other.