If an AM station can maintain its audio quality and coverage area, and at the same time reduce its own energy consumption, the FCC is all for it. The technology exists to make it possible, and the Commission is poised to grant waivers to stations that wish to put it to use.
The technologies fall under the general heading Modulation Dependent Carrier Level control technologies or algorithms, or MDCL, and have been in use by high-power overseas broadcasters for some time. In order to use such technologies in the US, however, a waiver is required, and the FCC is signaling in no uncertain terms that it is now prepared to issue such waivers.
FCC offered background on the offer, saying, “Transmitter manufacturers have developed different techniques to reduce carrier power as the audio content varies. During the 1980s, several European broadcasting and manufacturing concerns developed algorithms to reduce power consumption by radio transmitters. These algorithms, known variously as Dynamic Amplitude Modulation, Amplitude Modulation Companding, Adaptive Carrier Control, or Dynamic Carrier Control, decrease carrier power by amounts up to 6 dB, with the power reductions applied at different modulation levels depending on the algorithm.”
It added that equipment manufacturers have necessary equipment ready to go, and said, “The potential for energy savings depends upon the particular technology and its configuration, and also upon the program content. In typical cases, the power consumption of an AM transmitter can be reduced by 20 to 40 percent.”
FCC says there may be a “penalty” in terms of lost audio quality or increased distortion, but says that in most cases the change is imperceptible. The also say that test show the MDCL systems to be compatible with AM IBOC technology.
Waiver requests are to be mailed to:
Federal Communications Commission
Audio Division, Media Bureau
445 12th Street SW, Room 2-B450
Washington, DC 20554
A copy of the request, preferably in .pdf format, shall be sent by e-mail to [email protected].