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SIMULCAST DELIVERED AUDIO QUALITY IMPROVEMENT METHOD VIA SUBAUDIBLE SIGNALLING PARITY

IP.com Disclosure Number: IPCOM000006305D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2001-Dec-21

Publishing Venue

Motorola

Related People

Authors:
Paul Cizek Mark Nowak

Abstract

FM simulcast systems are typically designed such that regions exist in which signals from 2 or more remote sites overlap. In these regions, to recover an intelligible signal, it is critical to keep the signals in phase by care- fully setting the delays and equating the frequency mod- ulation constants ofthe transmitters to reduce simulcast distortion. This is especially true in the overlap regions of equal signal strength where in the case of a two-site system. I80 degrees of phase difference will cause com- plete cancellation of the received signal. Such occurrences result in spikes in the demodulated signal that produce audible "pops:' These pops reduce the overall audio qual- ity of the received signal.