Patent ID: 6687309
Filing Date: 2004-02-03
Classification: H04L

Abstract:
A system for estimating carrier frequency of an applied QAM signal relative to a target carrier frequency, comprising:a converter, converting the applied QAM signal to an IF signal and digitizing the IF signal at a predesignated sample rate; a complex signal generator, receiving the digitized IF signal, extracting a real component of the digitized IF signal and performing a Hilbert Transform on the extracted real component to provide an imaginary component of the digitized IF signal, the complex signal generator combining the real component and the imaginary component in a complex signal; an exponentiator, raising the complex signal to a predesignated power; an FFT module, performing a FFT, having a predetermined number of samples, on the complex signal as raised to the predesignated power; and a processor, taking the magnitude of the resulting FFT, extracting the index of a sample within the resulting FFT having the greatest magnitude and estimating the carrier frequency of the applied QAM signal relative to a target carrier frequency based on the predesignated power, the extracted index, the predetermined number of samples and the predesignated sample rate.