Patent ID: 7541966

Claim:
A demodulating apparatus, comprising: an analog to digital converter for converting an analog modulated input signal to a digital signal having an associated frequency, the analog to digital converter sampling the input signal at a predetermined sampling rate; a digital down converter for receiving the digital signal from an output of the analog to digital converter at the sampling rate, the digital down converter reducing the frequency of the digital signal from the predetermined sampling rate to one quarter of the sampling rate; a low pass filter for receiving an output signal from the digital down converter and for filtering selected frequencies therefrom to produce a filtered output signal; a frequency offset stage for receiving the filtered output signal and for producing a modified signal by applying a modification to the frequency of the filtered output signal to reduce a frequency offset in the filtered output signal, and a differential demodulator for demodulating the modified signal produced by the frequency offset stage to reduce the frequency offset in the modified signal.