Simplified High Frequency Tuner and Tuning Method
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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.
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Citations
120 Claims
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1-78. -78. (canceled)
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79. A method of tuning a signal of interest from a channelized spectrum, comprising:
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(a) splitting an incoming signal into two signal paths; (b) generating an approximately quadrature local oscillator signal; (c) quadrature mixing the split incoming signal with the local oscillator signal, thereby producing I and Q signals in approximate quadrature relation; (d) filtering the I signal with a first passband filter and filtering the Q signal with a second passband filter, wherein each filter defines a near-baseband passband, the lower edge of which is spaced from DC by at least about the passband width; (e) subjecting one of the filtered I and Q signals to a phase shift of about 90 degrees relative to the other, thereby producing second I and Q signals; and (f) summing the second I and Q signals, thereby producing a real-valued signal. - View Dependent Claims (80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94)
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95. Apparatus for tuning, from a channelized spectrum having a predetermined channel spacing, a channel of interest, the apparatus comprising:
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(a) a local oscillator configured to generate a quadrature local oscillator signal; (b) an amplifier responsive to an RF signal of interest; (c) a pair of mixers that are responsive to the amplified signal of interest and the quadrature local oscillator signal, thereby producing I and Q signals in approximate quadrature relation; (d) a first passband filter responsive to the I signal and a second passband filter responsive to the Q signal, wherein each filter defines a near-baseband passband, the lower edge of which is spaced from DC by at least about the passband width; and (f) a summer responsive to (1) a first one of the filtered I and Q signals from the first and second passband filters, and (2) a version of the second one of the filtered I and Q signals that has been subjected to a phase shift of about 90 degrees relative to the first one of the filtered I and Q signals. - View Dependent Claims (96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106)
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107. A method of tuning a channel of interest from a channelized spectrum, comprising:
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(a) splitting an incoming signal containing a channel of interest into two signal paths; (b) generating an approximately quadrature local oscillator signal; (c) quadrature mixing the split incoming signal with the local oscillator signal, thereby producing I and Q signals in approximate quadrature relation; (d) filtering the I signal with a first filter and filtering the Q signal with a second filter; (e) subjecting one of the filtered I and Q signals to a phase shift of about 90 degrees relative to the other, thereby producing second I and Q signals; and (f) summing the second I and Q signals, thereby producing a real-valued signal; (g) wherein the channel of interest is frequency translated to within a near-baseband passband, the lower edge of which is spaced from DC by at least about the channel spacing. - View Dependent Claims (108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119)
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120-166. -166. (canceled)
Specification