Patent ID: 7203254

Claim:
A method for using a receiver to achieve timing synchronization during acquisition of a signal, the method comprising the steps of: receiving a signal from the transmitter containing a plurality of data slots and a sync word within each transmitted data slot; forming multiple correlations at each of a plurality of time instants, each of said multiple correlations corresponding to a selected sync symbol interval relative to a current time instant, by correlating the received signal with a sinusoid of an expected frequency for each of the selected sync symbol intervals; gathering the multiple correlations at each time instant; phase correcting the multiple correlations in accordance with an FSK modulation index and a known sync symbol pattern, thus forming a vector of multiple phase corrected sync symbol correlations; computing at each time instant a discrete-time Fourier transform of the vector over a set of candidate offset frequencies; forming a sync correlation signal according to a maximum discrete-time Fourier transform amplitude at each time instant among the set of candidate offset frequencies; comparing the sync correlation signal to a threshold at each time instant, wherein the threshold is proportional to energy in the received signal over the time span of a sync signal relative to a current time instant; and upon detecting that the sync correlation signal has exceeded the threshold, locating a peak of the sync correlation signal and establishing symbol timing in accordance with the peak.