Synchronizer for TDMA acquisition signal having an unknown frequency

U.S. Patent Number: 5383225

Abstract: A synchronizer operates to achieve initial synchronization with a TDMA acquisition signal exhibiting a potentially large Doppler. The synchronizer collects samples of a baseband signal during a timing window. A fast Fourier transform (FFT) is performed on the samples to generate a set of spectral data. The window is moved to an identical point in a subsequent frame and the FFT repeated until a high-confidence spectral data set is obtained. If the spectral data set indicates energy concentrated around a discrete frequency, then that discrete frequency represents an estimate of the acquisition signal's frequency. The timing window's timing parameters represent a time slot estimate of the acquisition signal. If the spectral data set indicates energy spread more or less uniformly over the spectrum, then no estimates are indicated and a new window is positioned at a different point in subsequent frames.

Inventors: Aguirre; Sergio (Boulder, CO), Keate; Christopher R. (Santa Clara, CA), Vatt; Gregory B. (Mesa, AZ)

Assignee: Motorola, Inc. (Schaumburg, IL)

Application Number: 07/991,816

Issued: 1995-01-17

Expired: 2007-01-17

Classes: 375/354 ; 370/337; 370/350; 375/356; 375/364

Field of search: 370/105,105.1,104.1,93 375/107,110,113,106

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