Patent ID: 7894552

Claim:
A software defined radio, comprising: an analog-to-digital converter for receiving an intermediate frequency signal; a mixer operatively coupled to the analog-to-digital converter; a combiner operatively coupled to the mixer; an in-phase component generator and a quadrature component generator operatively coupled to the combiner; a splitter operatively coupled to the mixer with an in-phase signal output and a quadrature signal output; and an interpolation unit operatively coupled to one selected from the in-phase signal output of the splitter and the quadrature signal output of the splitter; wherein the analog-to-digital converter converts the intermediate frequency signal, the combiner combines the in-phase component and the quadrature component, the mixer mixes the converted signal and the combination, the splitter splits the mixed signal into an in-phase signal and a quadrature signal, and the interpolation unit interpolates one selected from the in-phase signal and the quadrature signal, wherein the interpolation unit comprises a parabolic interpolation unit, and wherein the parabolic interpolation unit comprises: a first sample delay component for receiving one selected from the in-phase signal and the quadrature signal; a second combiner for receiving the one selected from the in-phase signal and the quadrature signal, operatively coupled to the first sample delay component; a third combiner for receiving the one selected from the in-phase signal and the quadrature signal; a second sample delay component operatively coupled to the first sample delay component, the second combiner, and the third combiner; a first shift unit operatively coupled to the second combiner; a second shift unit operatively coupled to the third combiner; and a fourth combiner operatively coupled to the first shift unit and the second shift unit; wherein the first sample delay component delays the one selected from the in-phase signal and the quadrature signal by one sample, the second combiner combines the one selected from the in-phase signal and the quadrature signal with the negative of the delayed signal of the first sample delay component and the delayed signal of the second sample delay component, the third combiner combines the one selected from the in-phase signal and the quadrature signal with the negative of the delayed signal of the second sample delay component, the first shift unit shifts the combination of the second combiner, the second shift unit shifts the combination of the third combiner, and the third combination unit combines the delayed signal of the first sample delay component with the shift of the first shift unit and the shift of the second shift unit.