Research Of DRM System And Design Of Demultiplexer In DRM Receiver

AM radio is taken for granted, for its large coverage and simple receiver. However, radio listeners are becoming more sophisticated and discerning, and have more sources of entertainment and information available to them all the time. Present AM radio cannot match the sound quality of FM radio, let alone CDs and other digitally stored or received formats, so listeners have every incentive to desert AM radio. Keeping the strongpoint of conventional AM radio and avoiding the weakness of it, the advent of DRM (Digital Radio Mondiale) is a new chance for the development of wireless broadcasting, especially AM broadcasting.In the first place, this paper analyzes the current condition, merits and flaws of conventional AM radio to make the aims and required matters of DRM clear. Also, the advantage of DRM and its operation procedure is introduced. Then, it researches and analyzes DRM system construction and transmittion modes, and introduces several key techniques of DRM system. DRM transmission system is comprised of source encoders, multiplexer, channel encoder and QAM modulation, OFDM cell mapping and OFDM signal generator, RF modulation and so on. At the receiver end, signal flows in the inverse way of above. DRM system offers different transmission modes for varied bands and circumstances. Each transmission mode is defined by signal bandwidth related parameters and transmission efficiency related parameters. Finally, the design of DRM software receiver and demultiplexer is discussed in this paper. The demultiplexer is designed with Visual C++, which is used to divide the audio data and data application in MSC. The first thing to do is to extract the position information of processed data, and the second thing is to get audio data and data application in different ways according to whether hierarchical frame is appear or not. In the last part of this paper, some test results are provided to prove that the demultiplexer can work well.