Single Frequency Networks (SFNs) are a form of broadcast network design where several transmitters use the same frequency channel to send the same signal. SFNs are usually used for radio and digital TV broadcasting- FM, AM and digital radio can be transmitted over SFNs – while analog television is more problematic because the multiple signal sources tend to produce ghosting.
Why would a broadcaster choose this technique? There are several potential advantages. One is the greater efficiency that SFN can provide: a broadcaster’s available spectrum can be packed with more radio and TV channels than would be possible with a multifrequency topology.