| For the convenience and portability, broadcasting has a wide range of audiences, which contributes greatly to the development of communication in China. However, with the digitization of communication systems and the widespreading of Internet and multimedia, analog broadcasting can no longer satisfy people’s demand for better quality and wide variety of mass information. Thus, the digitization of communication systems is inevitable. As the mainstream of digital broadcast systems, Digital Radio Mondiale (DRM) largely reduces the negative effect of frequency selective fading and multipath phenomenon, and also increases the capacity of the system by using many advacned techniques, such as efficient audio coding, OFDM, multilevel channel coding, interleaving and error protection, and sideband recovery technologies. DRM+ is a draft for DRM focusing on the digitization of FM frequency range.In this thesis, the process of DRM+ evolution and its current situation are introduced. The importance of this thesis is presented by comparing with Digital Audio Broadcasting (DAB) and High-Definition Radio (HD Radio). The structure of transmitting system and the procedure of signal processing are introduced here, and the analysis of key techniques of DRM+ system performance is also included. We also designed a scheme for a base-band signal processing. And it is thoroughly described by steps in this thesis. Based on this scheme, the acquisition of complex baseband signal, the synchronization of OFDM, and the channel estimation are analyzed and introduced respectively. Combined with the features of DRM+ system, the methods of demapping transimission supper frame, decoding punctured convolution code and AAC voice code are designed. The scheme is realized and tested with C programming language on the platform of Windows. And finally the program is transplanted to WinCE system on the platform of DM3730, which implements the function of embedded baseband signal processing. |
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