Simplified high frequency tuner and tuning method
DCFirst Claim
1. An apparatus for tuning any channel of interest from a channelized spectrum having a predetermined channel spacing, the apparatus comprising:
- (a) a local oscillator configured to generate a local oscillator signal frequency either above or below the frequency of the channel of interest;
(b) a first mixer and a second mixer, each having an input coupled to the local oscillator and a radio frequency antenna configured to receive the channel of interest, the first and the second mixer configured to frequency translate the channel of interest;
(c) a filtering block having two inputs, the inputs being respectively coupled to the first and second mixer outputs and further wherein one of the inputs is in approximate phase quadrature with a second input, the filtering block configured to filter the frequency translated channel of interest; and
,(d) a selector structured to dynamically select either a frequency translated upper high frequency spectrum of interest or a frequency translated lower high frequency spectrum of interest for demodulation;
(e) wherein the frequency translated channel of interest is within a near-baseband passband spaced from DC by at least about 20 kHz.
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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
26 Claims
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1. An apparatus for tuning any channel of interest from a channelized spectrum having a predetermined channel spacing, the apparatus comprising:
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(a) a local oscillator configured to generate a local oscillator signal frequency either above or below the frequency of the channel of interest; (b) a first mixer and a second mixer, each having an input coupled to the local oscillator and a radio frequency antenna configured to receive the channel of interest, the first and the second mixer configured to frequency translate the channel of interest; (c) a filtering block having two inputs, the inputs being respectively coupled to the first and second mixer outputs and further wherein one of the inputs is in approximate phase quadrature with a second input, the filtering block configured to filter the frequency translated channel of interest; and
,(d) a selector structured to dynamically select either a frequency translated upper high frequency spectrum of interest or a frequency translated lower high frequency spectrum of interest for demodulation; (e) wherein the frequency translated channel of interest is within a near-baseband passband spaced from DC by at least about 20 kHz. - View Dependent Claims (2, 3)
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4. An apparatus for tuning any channel of interest from a channelized spectrum having a predetermined channel spacing, the apparatus comprising:
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(a) a tunable local oscillator configured to generate a local oscillator signal frequency either above or below the frequency of the channel of interest, and having a tuning step size approximately equal to the channel spacing; (b) a first and a second mixer respectively coupled to the local oscillator signal and a quadrature local oscillator signal having an approximate 90 degree phase shift relative to the local oscillator, and each mixer further coupled to a radio frequency antenna configured to receive the channel of interest, the first and second mixers configured to selectively frequency translate the channel of interest from either above the local oscillator frequency or below the local oscillator frequency; (c) a phase shifting element coupled to either the first or the second mixer output and configured to generate a signal that is in phase quadrature with the input signal; and
,(d) a selector structured to dynamically select either an upper high frequency spectrum of interest or the lower high frequency spectrum of interest from the frequency translated signal; (e) wherein the selected high or low frequency spectrum of interest falls within a near-baseband passband that is spaced from DC by at least about 20 kHz. - View Dependent Claims (5, 6, 7, 8)
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9. An apparatus for tuning any channelized signal of interest from a channelized spectrum having a predetermined channel spacing, the apparatus comprising:
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(a) a local oscillator configured to generate a local oscillator signal that is coarse-tunable across the channelized spectrum with a step size that at least an integer multiple of the channel spacing; (b) a filtering element defining a near-baseband passband spaced from DC by at least about 20; (c) a first and a second mixer, each coupled to the local oscillator and a radio frequency antenna configured to receive the channelized signal of interest, and the mixers configured to translate to the near-baseband passband; (1) an upper high frequency spectrum of interest from above the frequency of the local oscillator signal, and (2) a lower high frequency spectrum of interest from below the frequency of the local oscillator signal; and (d) a control structure that is configured to dynamically select one of the high frequency spectra of interest. - View Dependent Claims (10, 11)
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12. An RF tuner comprising:
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(a) analog circuitry including (i) a local oscillator that provides a first local oscillator signal having a frequency FLO and a second local oscillator signal having the frequency FLO approximately in quadrature to the first local oscillator signal, (ii) a first mixer operable to mix the first local oscillator signal with an incoming signal to provide a first mixer output comprised of an upper high frequency signal spectrum of interest above FLO and a lower high frequency signal spectrum of interest below FLO wherein both the upper high frequency signal spectrum of interest and the lower high frequency spectrum of interest are frequency-translated to within a near-baseband passband by the mixing with the first local oscillator signal, (iii) a second mixer operable to mix the second local oscillator signal with the incoming signal to provide a second mixer output comprised of the upper high frequency signal spectrum of interest above FLO and the lower high frequency signal spectrum of interest below FLO, wherein both the upper high frequency signal spectrum of interest and the lower high frequency signal spectrum of interest are frequency-translated to within the near-baseband passband by the mixing with the second local oscillator signal, (iv) first circuitry configured to at least filter the frequency spectrum output by the first mixer, and (v) second circuitry configured to at least filter the frequency spectrum output by the second mixer; and (b) digital circuitry including; (i) a first analog-to-digital converter that provides a first converter output comprised of the output of the first circuitry configured to at least filter the frequency spectrum converted from analog to digital format, and (ii) a second analog-to-digital converter that provides a second converter output comprised of the output of the second circuitry configured to at least filter the frequency spectrum converted from analog to digital format; and (c) wherein the digital circuitry is adapted to combine the first and second converter outputs to provide an image-rejected signal within the near-baseband passband by substantially rejecting the near-baseband image of a dynamically selectable one of the upper high frequency signal spectrum of interest and the lower high frequency signal spectrum of interest. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification