Patent ID: 8116705

Claim:
A method for tuning a signal of interest from within a channelized spectrum, the method comprising: (a) splitting an incoming signal into two signal paths; (b) generating an approximately quadrature local oscillator signal from a local oscillator that is coarse-tunable across the channelized spectrum with a step size that is an integer multiple of the channel spacing; (c) quadrature mixing the split incoming signal with the local oscillator signal, thereby: (1) frequency translating to a near-baseband passband an upper high frequency spectrum of interest from above the frequency of the local oscillator signal and a lower high frequency spectrum of interest from below the frequency of the local oscillator signal, the near-baseband passband being defined with reference to a lower frequency F 1 and an upper frequency F 2 , wherein F 1 =F 2 −F 1 and F 1 is at least about the maximum bandwidth of the signal of interest; and (2) producing I and Q signals in approximate quadrature relation; (d) limiting the frequency spectrum of the I and Q signals, wherein spectrum coverage is provided of a selected one of the high frequency spectra of interest and analog processing of signals at or close to DC is avoided; and (e) repeating (a) through (d) in turn for a plurality of local oscillator frequencies, wherein high frequency spectra of interest tunable with the local oscillator frequencies of the plurality are interspersed among local oscillator frequencies of the plurality within the channelized spectrum.