Research And Design Of DAB Transmission System

With the advances of technology and life quality, we have got used of enjoying the high quality music from MP3 and CD, and obtaining abundant information from more flexible carriers such as internet, interactive TV and multimedia equipments. The traditional broadcasting, which used to be the most common audio-based information carrier, has shown continuous degradation in recent years. This awkward situation is partly resulted from some intrinsic disadvantages of the traditional broadcasting technology, such as poor sound quality, susceptibility to be interfered, incapability of receiving signals at high-speed moving status, monotonic program forms, high transmission power and small coverage area. The best way to solve these problems and rebloom the traditional broadcasting is to digitalize broadcasting.Digital audio broadcasting (DAB) is a new-generation technology of broadcasting after the AM and FM radio. DAB has a lot of advantages such as the low transmission power, large coverage area, high frequency spectrum utilization and reliable delivery to mobile receivers. Moreover, as a new multimedia broadcasting technology, DAB can deliver audio signals and the other digital signals such as the image, text, data and video information at the same time.The aim of this thesis is to design a DAB transmission system which can complete the baseband encoding from the source to the channel. The source encoding part consists of the audio coding module, the video coding module, and the CD reading and converting module, which can realize the real time audio/video encoding. The channel encoding part consists of the FIC encoding module, the ETI encoding module and the baseband encoding module, which can achieve the DAB baseband signal processing. These two parts are completed by two softwares connected by a data transfer module based on TCP/IP protocol. The designed DAB transmission system can be used to form a DAB radio station by combining combined with the OFDM module and DAB transmitter. We have completed all the coding work in Microsoft Visual C++ 6.0 using C++, and developed the control interface for each function.A DAB radio station has been built by combining the software with the hardware for verifying the designed system. The DAB program coding and transmission can be done with this station. A DAB receiver is used to decode the broadcast signals and test whether the system meets the design aim or not from the decoding results. Testing results show that various receivers made in China or abroad can all receive the broadcast signals. All the programs can be decoded and played smoothly without obvious distortion from original audio/vedio information, and the DAB reconfiguration function is also supported. In addition, the designes system has been used for testing the DAB receivers in the lab for long-time transmission-receiving tests. From the above testing results we can conclude that all the designed modules of this system work stably. Mulitple sets of audio/vedio programs can be coded and modulated correctly, outputing data stream satisfying the DAB standards. The performance of the system meets the design requirements.