Abstract: A homodyne down-converter, for use in an IF signal demodulator and the like, includes an analog-to-digital converter (ADC) which receives the IF analog signal for conversion to a digital data stream by sampling at a sampling rate frequency substantially equal to four times the IF signal frequency. A digital mixer controllably inverts the sampled data to convert the data to baseband, before a circuit removes the effects of DC offset in the analog IF signal applied to the ADC. A discrete Hilbert Transform filter is used for generating streams of sequential in-phase I' and quadrature-phase Q' data words, which are resampled to temporally align the two data word streams at a new data rate, thus effectively removing sample offset without the need for separate misalignment correction circuitry.

Abstract: A digital subharmonic sampling converter, for use in an analog IF signal demodulator and the like, includes: an analog-to-digital converter (ADC) means receiving the IF analog signal for conversion to a digital data stream by sampling at a sampling rate frequency substantially equal to 4/(2n+1) times the IF signal frequency, where n is an integer greater than zero. A digital mixer means is used to convert the sampled data to baseband. The interleaved sequential in-phase I data words and quadrature-phase Q data words are then sorted into a pair of concurrent I and Q data word streams.