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single frequency network (SFN)

Common wave networks or common wave radio (GWF) are terrestrial transmitter networks with several transmitters that all transmit on the same frequency. The antennas of the transmitters can be positioned in such a way that they illuminate a specific transmission area, regardless of the topographical characteristics. In addition, they operate in a frequency-efficient manner because, unlike single-transmitter systems, the received field strength

is not dependent on the radiated power, antenna mast height or distance. The individual transmitter signals of a common wave network do not interfere with each other, but interfere with each other by amplifying each other. If no or only limited reception is possible in certain regional areas due to the topology of the terrain, in tunnels or buildings, this can be compensated for by so-called filler transmitters

.

Structure of a common wave radio network

Structure of a common wave radio network

The topology of common wave networks consists of a control centre and several common wave transmitters, all of which transmit in the same frequency band

and on the same frequency.Regardless of whether stationary or mobile receivers are being supplied, within the transmission area a radio receiver receives the same radio frequencies from several different transmitters. Since the receivers receive the same frequency from several transmitters at the same time, frequency overlaps and interference occur. For these reasons, receivers work with this diversity and suppress transmitters that come in with low received field strengths

. This is called the FM suppression effect (capture effect), which ensures perfect radio coverage even in the overlapping areas of a common wave. Itis important that all transmitters must not have any differences

inthe carrier

frequency, thefrequency dev

iationand the phase position

. Common wave radio is used in BOS radio (authorities and organisations with security tasks), in amateur radio, in terrestrial digital TV, DVB-T, DVB-H and in digital broadcasting.

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Englisch: single frequency network - SFN
Updated at: 10.01.2014
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