Patent ID: 7606549

Claim:
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.