Delco Electronics Corporation

Roger Alan McDanell

Terrance Ralph Beale

A differential demodulator that is particularly suited for a digital audio broadcasting (DAB) system, and more particularly to the Eureka-147 (DAB) system, is disclosed. The differential demodulator of the present invention receives complex data components I and Q derived from a fast fourier transform operation and converts the data components I and Q into differential data components .DELTA.I and .DELTA.Q that are accepted by data demodulating elements of the Eureka-147 system so as to be reconstructed as digital data which, in turn, are converted into an analog form that is converted and reproduced into corresponding high quality sound. The conversion of I and Q data into .DELTA.I and .DELTA.Q data is accomplished via a network of four ROMs and one RAM, wherein the ROMs are time-shared between the multiple carriers of the Eureka-147 system.

Differential demodulator

A synchronization network that provides frame timing that is particularly suited for a Eureka-147 system is disclosed. The synchronization network reduces the typical amount of computations required to provide for frame timing schemes and includes matched filtering operations that separate the waveforms of null and sine symbols contained in the multiple carriers of the Eureka-147 system. The matched filtering technique are accomplished before a fast Fourier transform operation and which accomplishments elimination of the need of an inverse fast Fourier transform operation normally performed by one of the receiver elements of the Eureka-147 system. This elimination is accomplished without degrading the performance of the Eureka-147 system.

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Kokomo, IN, United States of America

Roger Alan McDanell