FAQ
DCC causes the carrier wave level to be automatically reduced when the audio is very weak or no audio is present. During periods of silence (no audio), the carrier power is reduced by 50%, so the 250 kW transmitter is putting out a carrier of 125 kW during audio pauses. This carrier power reduction saves otherwise wasted electricity.
There is a BBC mode DCC that behaves the exact opposite to the DCC as it is described above. BBC World Service and relay stations are the only place where transmitter using the BBC-DCC mode. BBC-DCC is said to work better than plain DCC, as it allows the receiver to remain locked to the carrier. DCC can work with frequency modulation (FM), but was never adopted for high-power FM stereo transmission.
Read more about this topic: Dynamic Carrier Control