Research Of Audio Decoding Theory And Design Of Audio Decoder In DRM System

AM receiver is very simple, and it has such a large coverage ability that it has become the best tool to achieve national and international coverage of radio. Other digital media can not be comparable with it in mobility. Therefore,AM radio has been accepted by people for many years. According to the investigation, there are about two billion AM receivers all over the world. However, with the emerge of many new digital media and some disadvantage of itself, AM radio lost many of its audience. People try to find a new technology which can replace the function of it. DRM system inherits the great advantage of AM radio and discards the disadvantage of it. DRM system gives AM radio a second chance.In this paper, the disadvantage of DRM is discussed, and the value of researching it is also included. The paper includes some other information, the flow of DRM system, the architecture of DRM system and some key technologies used in DRM, such as source coding, COFDM and QAM modulating. The audio coding and decoding is one of the cores in DRM system. The theory of audio coding and the flow of MPEG-4 AAC are discussed in this paper. It also includes the theory and application of some tools in MPEG-4 AAC.At the end, the software design of audio decoder is introduced in the paper, which is based on the former discussion of audio coding theory. The software is debugged and run as one part of the whole DRM software receiver, the result of the experiment shows that it works stably.