System and method of eliminating or minimizing LO-related interference from tuners

A method of avoiding interfering signals in an electronic system, said method comprising:

• determining an output band of interest for a tuner;
• selecting a first intermediate frequency (IF);
• determining a first mixing frequency;
• determining a second mixing frequency;
• identifying a spurious signal as a function of particular harmonics of said first and second mixing frequency;
• defining an exclusion zone of first IF values associated with the spurious signal, said exclusion zone containing first IF values resulting in the spurious signal within the output band of interest;
• and
• selecting a new IF value outside of the exclusion zone in order to shift the spurious signal from the output band of interest.

A method of minimizing interference from multiple tuners, said method comprising:

• selecting a first intermediate frequency (IF) for a first tuner;
• determining a mixing frequency for the first tuner associated with said first IF;
• determining a mixing frequency for a second tuner;
• identifying a first spurious signal as a function of particular harmonics of said mixing frequency of the first tuner, said mixing frequency of the second tuner, or both;
• selecting a different first IF value which rejects the first spurious signal from an output band of interest;
• determining a different mixing frequency for the first tuner associated with said different first IF;
• identifying a different spurious signal as a function of particular harmonics of said different mixing frequency of the first tuner, said mixing frequency of the second tuner, or both;
• and
• selecting either the first IF value or the different first IF value based on a spur criteria in order to minimize interference within the output band of interest.

A multiple tuner system comprising:

• a first tuner having a mixer which accepts an input signal and a mixing signal to generate a first intermediate frequency (IF);
• a second tuner having a mixer and a mixing signal;
• means for determining an output band of interest for the first tuner;
• means for identifying a spurious signal as a function of particular harmonics of the mixing signals;
• means for defining a zone of first IF values associated with the spurious signal, said zone containing first IF values yielding the spurious signal within the output band of interest;
• and
• means for selecting a new first IF value outside of the zone which rejects the spurious signal from the output band of interest.

A method of minimizing interference from multiple tuners, said method comprising:

• determining an input frequency band (fIN) and output frequency band (fOUT) for a first tuner;
• selecting a first intermediate frequency (fIF1) for the first tuner;
• determining local oscillator frequencies (fLO1,1 and fLO2,1) of the first double conversion tuner to provide a desired signal appearing in the input frequency (fIN) at the first intermediate frequency (fIF1) and within the output frequency band (fOUT);
• determining local oscillator frequencies (fLO1,2 and fLO2,2) of a second double conversion tuner;
• identifying a first spurious signal associated with interaction of at least 2 said local oscillator frequencies (fLO1,1, fLO2,1, fLO1,2, and fLO2,2);
• selecting a different first IF (f′IF1.), which rejects the first spurious signal from the output band of interest;
• identifying a different spurious signal associated with interaction of said at least 2 said local oscillator frequencies (fLO1,1, fLO2,1, fLO1,2, and fLO2,2);
• and
• selecting either fIF1, or f′IF1, based on spur criteria and accepting the associated spur within the output band of interest.

A multiple tuner system comprising:

• a first tuner having a mixer which accepts an input signal and a mixing signal to generate a first intermediate frequency (IF);
• a second tuner having a mixer and a mixing signal;
• and
• a system controller having means for determining an output band of interest for the first tuner;
• means for identifying a spurious signal as a function of particular harmonics of the mixing signals;
• means for defining a zone of first IF values associated with the spurious signal, said zone containing first IF values yielding the spurious signal within the output band of interest;
• and means for selecting a new first IF value outside of the zone which rejects the spurious signal from the output band of interest.

An algorithm for selecting between a set of spurious signals existing on a multiple tuner system, said algorithm comprising:

• determining an output band of interest for a first tuner;
• selecting a first intermediate frequency (IF) for the first tuner;
• determining a mixing frequency for each of the first tuner and a second tuner;
• identifying a first spurious signal as a function of particular harmonics of said mixing frequency of the first tuner, said mixing frequency of the second tuner, or both;
• selecting a different first IF value which rejects the first spurious signal from the output band of interest;
• identifying a different spurious signal as a function of particular harmonics of a different mixing frequency of the first tuner, said mixing frequency of the second tuner, or both;
• and
• selecting either the first IF value or the different first IF value based on a spur criteria in order to minimize interference within the output band of interest.

A method of operating two tuners in close proximity, said method comprising:

• selecting a mixing frequency for a first tuner;
• determining an output band of interest for a second tuner;
• selecting a first intermediate frequency (IF) for the second tuner and determining a mixing frequency for the second tuner;
• identifying a first spurious signal as a function of particular harmonics of said mixing frequency of the first tuner, said mixing frequency of the second tuner, or both;
• selecting a different first IF value which rejects the first spurious signal from the output band of interest and determining a different mixing frequency for the second tuner;
• identifying a different spurious signal as a function of particular harmonics of said different mixing frequency of the second tuner, said mixing frequency of the first tuner, or both;
• and
• selecting either the first IF value or the different first IF value based on a spur criteria in order to minimize interference within the output band of interest of the second tuner.