Patent ID: 7336732
Filing Date: 2008-02-26
Classification: H04L

Abstract:
1. A method of detecting a carrier frequency in a received modulated signal, comprising the steps of: (a) filtering the received signal to pass the received signal in a band of frequencies including a carrier frequency at which the signal was received; (b) processing the filtered received signal to remove modulation components and thereby generate a test signal at the carrier frequency; (c) processing the test signal to provide an amplitude spectrum of samples at different test frequencies; and (d) processing the amplitude spectrum to detect the carrier frequency in accordance with the test frequency at which there is a test statistic of the highest magnitude; wherein step (d) comprises the steps of: (e) determining the magnitude of the test statistic by processing a signal statistic in relation to a noise statistic, wherein the signal statistic is the amplitude of the largest-amplitude sample; and (f) determining the noise statistic by averaging the amplitudes of samples outside of an exclusion region that includes the largest-amplitude sample, a number of samples immediately above the spectral position of largest-amplitude sample and a number of samples immediately below the spectral position of the largest-amplitude sample.