BE Claims Advance in Synchronous FM

BE Claims Advance in Synchronous FM
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Broadcast Electronics says its digital exciter technology has led to “a breakthrough in synchronous FM for broadcasters seeking continuous program coverage along highways or within a region under-served by a single FM signal.”
Stations precluded from synchronous FM because of unacceptable distortion artifacts in overlap zones are the likely benefactors of the FXi exciter system, the company stated; so are stations with existing systems compromised by distortion in key overlap areas.
BE said it is the first manufacturer to employ a totally digital approach to synchronous FM that provides significantly reduced distortion artifacts in overlap zones.
"Our new digital FXi exciter now makes it possible to synchronize the pilot and the carrier as well as the audio amplitude and frequency of two or more overlapped transmissions, thus reducing the interference issues associated with synchronous FM," according to Richard Hinkle, BE director of RF engineering.
The company said in its announcement that other approaches fail to completely synchronize the FM signals, resulting in degraded audio performance in the areas where the transmitted signals overlap and are of equal signal level.
“BE's FXi digital exciter synchronizes the carrier frequency, pilot frequency, audio amplitude and frequency precisely, therefore improving the signal-to-noise in areas where signals from each transmitter overlap.”
It said testing and use of the exciter for several stations in Greece “indicate that program continuity and quality is vastly improved compared to traditional synchronization approaches. This new system design technology reduces the interference zones and noise issues that have plagued other similar systems used for synchronizing more than one FM transmission.”
The supplier said its exciter is the only one o employ direct-to-channel modulation, which it said gives an additional 2 dB signal-to-noise compared to other digital designs that use analog up-conversion. A software feature has been added to synchronize with more precision the amplitude of audio coming from two FXi exciters. “The FXi exciter takes direct digital inputs, enabling two FXi exciters to be synchronized according to a shared carrier frequency as referenced by GPS. BE's synchronous FM system also uses uncompressed digital STLs to simultaneously feed audio to both transmission systems.”