Dynamic amplitude modulation

Dynamic amplitude modulation (DAM) is a method used in some amplitude-modulated radio transmitters , in which the amplitude of the carrier is adapted to the dynamics of the signal to be transmitted.

For example, the transmission power is reduced during pauses in speech, which saves energy compared to conventional amplitude modulation. This effect can be observed with a reception level indicator (like tube receivers with a magic eye , a pointer instrument or a flickering LED ). This was the case, for example, with the medium wave transmitter from SWR cont.ra on 576 kHz. With some transmitters, however, the power remains high during the pause in speech in order to avoid that the noise increases when receiving at the border of the coverage area.