Patent ID: 8693972

Claim:
A computer implemented method of down-converting an input signal from a first frequency band to a second frequency band, comprising: receiving in a processor a selected transfer function for converting the signal from the first frequency band to the second frequency band, the transfer function including a center frequency of the second frequency band; receiving in the processor a sequential series of samples of the input signal at a fixed interval from an array of sampling circuits; determining in the processor a plurality of sets of scaling factors, each set of scaling factors corresponding to coefficients in a Fourier series approximation of the selected transfer function and containing a different phase adjustment from the other sets of scaling factors; successively multiplying in the processor each of the samples of the input signal by the plurality of sets of scaling factors by rotating between the plurality of sets of scaling factors at the rate at which the samples of the input signal are received, each multiplication resulting in an interim output; and summing in the processor the interim outputs of the multiplications to create the output signal in the second frequency band.