Editing Digital Audio Broadcasting (section)

====Signal delay====
The nature of a [[single-frequency network]] (SFN) is such that the transmitters in a network must broadcast the same signal at the same time. To achieve synchronization, the broadcaster must counter any differences in propagation time incurred by the different methods and distances involved in carrying the signal from the multiplexer to the different transmitters. This is done by applying a delay to the incoming signal at the transmitter based on a timestamp generated at the multiplexer, created taking into account the maximum likely propagation time, with a generous added margin for safety. Delays in the audio encoder and the receiver due to digital processing (e.g. deinterleaving) add to the overall delay perceived by the listener.<ref name="tech.ebu.ch"/> The signal is delayed, usually by around 1 to 4 seconds and can be considerably longer for DAB+. This has disadvantages:
*DAB radios are out of step with live events, so the experience of listening to live commentaries on events being watched is impaired;
*Listeners using a combination of analogue (AM or FM) and DAB radios (e.g. in different rooms of a house) will hear a mixture when both receivers are within earshot.

[[Time signal]]s, on the contrary, are not a problem in a well-defined network with a fixed delay. The DAB multiplexer adds the proper offset to the distributed time information. The time information is also independent from the (possibly varying) audio decoding delay in receivers since the time is not embedded inside the audio frames. This means that built in clocks in receivers can be precisely correct.