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A single-frequency network or SFN is a type of radio network that operates several transmitters on a single frequency. To avoid interference, each station is usually run synchronously with the others, using GPS or a signal from the main station or network as a reference clock. Both FM and AM radio stations can run like this, as can other non-broadcast operations.
The conversion of broadcast television to digital transmission based on the MPEG algorithm and using 8VSB modulation in the United States may also present opportunities for broadcasters to improve their coverage area by operating multiple transmitters on the same frequency. This is in part because the nature of the digital technology is such that it requires a significant amount of "ghost cancelling" hardware or software in order for the digital data stream to be successfully recovered, even in ordinary conditions.
It therefore follows, that if a broadcaster augmented its transmission with an "on-channel" repeater in a weak coverage area, that in those areas where a receiver picks up both signals, the standard receiver design would simply interpret either repeater's signal or the main signal as a "ghost" signal of the other. Since the hardware is already designed with this capability, a more satisfactory result should ensue, as compared to what the expectation would be with respect to such an attempt in conventional broadcasting.
An alternative technical solution to the SFN is the multi-frequency network (MFN).
See also
repeater (booster)
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