Patent ID: 7903764

Claim:
A frequency shift keying (FSK) receiver, comprising: an RF converter configured to convert an RF signal to a digital sampled signal; a frequency determiner configured to generate a frequency indicator signal that is proportional to a change in frequency of the digital sampled signal; and a detector configured to determine a data value based on the frequency indicator signal; wherein the frequency determiner comprises: a first mixer configured to mix a local oscillator signal with a carrier offset signal to provide an adjusted local oscillator signal that has been compensated for a carrier offset in the digital sampled signal, wherein the carrier offset signal is calculated by averaging a plurality of samples of the frequency indicator signal; a second mixer configured to mix the digital sampled signal with the adjusted local oscillator signal to provide I and Q signal components from the digital sampled signal; a rectangular to polar conversion module configured to convert the I and Q signal components into an amplitude and phase of the digital sampled signal; and a derivative module configured to receive the phase of the digital sampled signal and produce the frequency indicator signal based on a derivative of the phase of the digital sampled signal.