Patent ID: 8324962

Claim:
An apparatus, comprising: a sine correlator having an input configured to receive an input signal, the input signal having a radian frequency that varies in relation to a state of the input signal, wherein the sine correlator is configured to generate an output that is about proportional to a sine of a product of the radian frequency of the input signal and a delay time; a cosine correlator having an input configured to receive the input signal, wherein the cosine correlator is configured to generate an output that is about proportional to a cosine of the product of the radian frequency of the input signal and the delay time; a first mixer configured to multiply the output of the sine correlator and a first quantity corresponding to a cosine of a phase control signal to generate a first product; a second mixer configured to multiply the output of the cosine correlator and a second quantity corresponding to a sine of the phase control signal to generate a second product; and a first adder configured to sum the first and second products to generate a demodulator output, the demodulator output proportional to about the sine of a product of the radian frequency of the input signal and the delay time shifted by a selectable phase shift, the phase shift selectable via control of the phase control signal.