Patent ID: 8619909
Filing Date: 2013-12-31
Classification: H04L

Abstract:
1. A method of detecting whether an incoming signal is a signal type of interest having a known training sequence, comprising: receiving an input signal of an unknown type, such that any carrier frequency offset is unknown; sampling the input signal at a known sampling frequency; filtering the input signal, using digital filter processing, by performing the following steps: calculating the conjugate of the training sequence, calculating the dot product of the conjugated training sequence and the input signal, and calculating the fast Fourier transform of the dot product; wherein the carrier frequency offset remains unknown prior to filtering the input signal and the filtering step is performed without prior mixing of the input signal; repeating the filtering step over an index of n iterations, where n is a sample index, thereby obtaining a series of filter outputs that are columns of a two-dimensional time-frequency matrix; and performing a two-dimensional search of the filter outputs against a detection threshold value, thereby obtaining a correlation value having a position in time and a position in frequency; using the results of the preceding step to obtain one or more of the following parameters of the input signal: start time of the training sequence, carrier frequency, and carrier offset.