Selective channel tuner and tuning method
AssigneeUniversity of Washington
InventorEdwin A. Suominen
Life of this patent
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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.
Claims20
A method of selectively tuning any wanted channel from a received signal, the received signal having a channelized spectrum with a uniform channel spacing, comprising:
- (a) setting a local oscillator to a first local oscillator frequency;
- (b) generating a first set of I and Q signals at the first local oscillator frequency displaced more than one channel spacing from the wanted signal center frequency;
- (c) mixing the first set of I and Q signals with the received signal;
- (d) selecting an upper high frequency spectrum of interest above the first local oscillator frequency;
- (e) setting the local oscillator to a second local oscillator frequency that is spaced from the first local oscillator frequency by an amount greater than or equal to the channel spacing;
- (f) generating a second set of I and Q signals at the second local oscillator frequency;
- (g) mixing the second set of I and Q signals with the received signal;
- (h) selecting a lower high frequency spectrum of interest below the second local oscillator frequency;
- (i) translating the selected frequency spectrum of interest to be demodulated to within a passband that is near baseband;
- and
- (j) spacing the lower edge of the passband that is near baseband from DC by at least about an amount greater than or equal to 20 kHz.
A method of selectively tuning any wanted channel from a received signal, the received signal having a channelized spectrum with a uniform channel spacing, comprising:
- (a) setting a local oscillator to a first local oscillator frequency displaced more than one channel spacing from the wanted signal center frequency;
- (b) generating a first set of I and Q signals at the first local oscillator frequency;
- (c) mixing the first set of I and Q signals with the received signal;
- (d) selecting a lower high frequency spectrum of interest below the first local oscillator frequency;
- (e) setting the local oscillator to a second local oscillator frequency that is spaced from the first local oscillator frequency by an amount greater than or equal to the channel spacing;
- (f) generating a second set of I and Q signals at the second local oscillator frequency;
- (g) mixing the second set of I and Q signals with the received signal;
- (h) selecting a upper high frequency spectrum of interest above the second local oscillator frequency;
- (i) translating the selected frequency spectrum of interest to be demodulated to within a passband that is near baseband;
- and,
- (j) spacing the lower edge of the passband that is near baseband from DC by at least about an amount greater than 20 kHz.
A method of selectively tuning any wanted signal from a received signal, the received signal having a channelized spectrum with a uniform channel spacing, comprising:
- (a) setting a local oscillator to a first local oscillator frequency displaced more than one channel spacing from the wanted signal center frequency;
- (b) generating a first set of I and Q signals at the first local oscillator frequency;
- (c) mixing the first set of I and Q signals with the received signal;
- (d) selecting an upper high frequency spectrum of interest above the first local oscillator frequency;
- (e) setting the local oscillator to a second local oscillator frequency that is spaced from the first local oscillator frequency by an amount greater than or equal to the channel spacing;
- (f) generating a second set of I and Q signals at the second local oscillator frequency;
- (g) mixing the second set of I and Q signals with the received signal;
- (h) selecting a lower high frequency spectrum of interest below the second local oscillator frequency;
- (i) translating the selected upper frequency spectrum of interest to be demodulated to within a passband that is near baseband using the first set of I and Q signals;
- (j) combining the outputs of I and Q mixers to reject interfering image signals appearing in the passband that is near baseband;
- and
- (k) spacing the lower edge of the passband that is near baseband from DC by at least about the bandwidth of the wanted signal.
A method of selectively tuning any wanted signal from a received signal, the received signal having a channelized spectrum with a uniform channel spacing, comprising:
- (a) setting a local oscillator to a first local oscillator frequency displaced more than one channel spacing from the wanted signal center frequency;
- (b) generating a first set of I and Q signals at the first local oscillator frequency;
- (c) mixing the first set of I and Q signals with the received signal;
- (d) selecting a lower high frequency spectrum of interest below the first local oscillator frequency;
- (e) setting the local oscillator to a second local oscillator frequency that is spaced from the first local oscillator frequency by an amount greater than or equal to the channel spacing;
- (f) generating a second set of I and Q signals at the second local oscillator frequency;
- (g) mixing the second set of I and Q signals with the received signal;
- (h) selecting a upper high frequency spectrum of interest above the second local oscillator frequency;
- (i) translating the selected high frequency spectrum of interest to be demodulated to within a passband that is near baseband;
- and
- (j) spacing the lower edge of the passband that is near baseband from DC by at least about the bandwidth of the wanted signal.
A method of selecting and switching between an upper high frequency spectrum of interest and a lower high frequency spectrum of interest associated with a down-converted signal of interest being any one selected channel from among a plurality of channels from a channelized spectrum having a uniform channel spacing, comprising:
- (a) adjusting a local oscillator to a first local oscillator frequency displaced more than one channel spacing from the wanted signal center frequency;
- (b) mixing the first local oscillator frequency with the channelized spectrum;
- (c) down-converting a radio frequency signal to a passband that is near baseband;
- (d) spacing the lower edge of the passband that is near baseband from DC by at least an amount greater than 20 kHz;
- (e) selecting and demodulating either an upper or lower high frequency spectrum of interest associated with the down-converted radio frequency signal and the first local oscillator frequency;
- (f) adjusting the local oscillator to a second local oscillator frequency that is spaced from the first local oscillator frequency by an amount greater than or equal to the channel spacing;
- (g) mixing the second local oscillator frequency with the channelized spectrum;
- (h) down-converting the radio frequency signal to the passband that is near baseband;
- (i) spacing the lower edge of the passband that is near baseband from DC by at least an amount greater than 20 kHz;
- (j) switching from the selected upper or lower high frequency spectrum of interest generated using the first local oscillator frequency to a selected lower or upper high frequency spectrum of interest, respectively, generated using the second local oscillator frequency.
A method of tuning channels of interest from a channelized spectrum comprising:
- (a) mixing a channel of interest from a channelized spectrum having a predetermined channel spacing with a first local oscillator signal, having a first frequency that is:
- (1) one half of a channel spacing displaced from the center frequency of the channel of interest;
- and
- (2) selected to frequency translate the channel of interest to within a passband that is near baseband and that extends near to but excludes DC;
- (b) mixing the channel of interest with a second local oscillator signal having the first frequency and being approximately in quadrature with the first local oscillator signal;
- and
- (c) selecting between:
- (1) providing spectrum coverage within a lower high frequency spectrum of interest and not an upper high frequency spectrum of interest;
- and
- (2) providing spectrum coverage within an upper high frequency spectrum of interest and not a lower high frequency spectrum of interest;
- (d) wherein the channel of interest:
- (1) has a predetermined maximum bandwidth less than the channel spacing;
- and
- (2) lies within one of an upper high frequency spectrum of interest and a lower high frequency spectrum of interest.
A method of tuning any one selected channel from among a plurality of selected channels of interest from a plurality of channels comprising:
- (a) at a first time, mixing a first selected channel of interest with a first local oscillator signal that has a frequency displaced above the first selected channel of interest by more than a channel spacing;
- (b) at a second time, mixing a second selected channel of interest with a second local oscillator signal that has a frequency displaced below the second selected channel of interest by more than a channel spacing;
- (c) frequency translating to a passband that is near baseband either the first selected channel of interest or the second selected channel of interest;
- and
- (d) reducing an image frequency of either the first selected channel of interest or the second selected channel of interest.
Dependencies are inferred from the claim text.