Simplified high frequency tuner and tuning method
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Abstract
A disdosed 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.
99 Citations
84 Claims
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1-65. -65. (canceled)
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66. A tuning device comprising:
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(a) input circuitry that receives an RF signal containing a channel of interest from a channelized spectrum; (b) mixers and local oscillator signal generators configurable to produce I and Q signals in approximate quadrature relation by mixing the channel of interest with an approximately quadrature local oscillator signal having a frequency that is one of a set of local oscillator frequencies determined by the channel spacing; and (c) filter circuitry configurable to filter the I and Q signals to define a near-baseband passband determined by the bandwidth of the signal of interest and whose lower edge is situated near baseband but spaced from DC by at least about the channel spacing.
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67. The tuning device of claim 66 wherein the channel of interest has a predetermined maximum bandwidth less than the channel spacing.
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68. The tuning device of claim 66 wherein the center frequency of the near-baseband passband is adjusted so that it is displaced by a frequency adjustment from either (i) an integer multiple of channel spacing from DC or (ii) a half-channel displaced from an integer multiple of channel spacing from DC.
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69. The tuning device of claim 68 wherein the frequency adjustment is about half of the channel spacing.
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70. The tuning device of claim 68 wherein the near-baseband passband is approximately a channel spacing wide.
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71. The tuning device of claim 70 wherein the near-baseband passband is wider than a channel spacing by a frequency adjustment.
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72. The tuning device of claim 68 wherein the frequency adjustment is predetermined.
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73. The tuning device of claim 68 wherein the frequency adjustment is static.
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74. The tuning device of claim 68 wherein the upper edge of the near-baseband passband is extended by a first frequency adjustment and the lower edge of the near-baseband passband is extended by a second frequency adjustment.
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75. The tuning device of claim 74 wherein the first and the second frequency adjustments are not equal.
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76. The tuning device of claim 66 wherein the near-baseband passband is wider than the width of the channel of interest by a predetermined frequency adjustment.
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77. The tuning device of claim 66 wherein the near-baseband passband is wider than the width of the channel of interest by a first frequency adjustment on the high edge of the channel of interest and a second frequency adjustment on the low edge of the channel of interest.
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78. The tuning device of claim 77 wherein the first and second frequency adjustments are predetermined.
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79. The tuning device of claim 75 wherein the edges of the near-baseband passband are separated by approximately the maximum bandwidth of the channel of interest.
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80. The tuning device of claim 79 wherein the edges of the near-baseband passband are wider than the spacing of the channel of interest by a predetermined frequency adjustment.
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81. The tuning device of claim 66 wherein the lower edge of the near-baseband passband is spaced from DC by about the channel spacing.
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82. The tuning device of claim 66 wherein the lower edge of the near-baseband passband is spaced from DC by about 1.5 times the channel spacing.
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83. The tuning device of claim 66 wherein the lower edge of the near-baseband passband is spaced from DC by about twice the channel spacing.
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84. The tuning device of claim 66 wherein the lower edge of the passband is spaced from DC by about 2.5 times the channel spacing.
Specification