Digital audio broadcasting in the FM band

It is envisioned that all broadcasting will be digital in the future. There are standards work and system development going on in various parts of the world to make this vision reality. In Europe, the emphasis has been on broadband systems (EUREKA) with multiple program channels in a new frequency band. In the United States, the broadcasting industry is favoring a solution where broadcasting is compatible with the existing analog FM and AM systems. A number of new digital audio radio systems have been proposed and evaluated. In this paper we present a conceptual overview of some of the properties of these systems. We also present the transmission channel properties of the FM systems. The most challenging part of the transmission is broadcasting to vehicles. We discuss details of key subsystems such as audio coding, channel coding, and digital modulation in the proposed in-band on channel (IBOC) and in-band adjacent channel (IBAC) as well as in-band reserved channel (IBRC) systems for the FM band