Single-frequency network

SFNs are not generally compatible with analog television transmission, since the SFN results in ghosting due to echoes of the same signal.

A simplified form of SFN can be achieved by a low power co-channel repeater, booster or broadcast translator, which is utilized as a gap filler transmitter.

In wideband digital broadcasting, self-interference cancellation is facilitated by the OFDM or COFDM modulation method.

OFDM is utilized in the terrestrial digital TV broadcasting system DVB-T (used in Europe and other regions), ISDB-T (used in Japan, Brazil, and the Philippines) and in ATSC 3.0.

[1] A GPS receiver worst-case scenario is able to provide +/- 1 μs time, well within the system needs of DVB-T SFN in typical configuration.

[2] It should be understood that the resolution of the mega-frame format is being in steps of 100 ns, whereas the accuracy needs can be in the range of 1-5 μs.

There is no strict need for an accuracy limit as this is a network planning aspect, in which the guard-interval is being separated into system time error and path time-error.

While not designed with on-channel repeaters in mind, the 8VSB modulation method used in North America for digital TV is relatively good at ghost cancellation.

ATSC SFNs have seen widest use in mountainous areas like Puerto Rico and Southern California, but are also in use or planned in gentler terrain.

[3] Early ATSC tuners were not very good at handling multipath propagation, but later systems have seen significant improvements.