Design And Implementation Of Digital Broadcasting System Based On MVB Communication

With the rapid development of urban rail transit construction, to provide passengers with comfortable and convenient service, the train broadcasting system is becoming increasingly important. In order to improve the limitations and reliability of the train broadcasting system, this thesis proposes a new model of broadcasting system which can achieve multiple full duplex communications. The digital audio transmission will be used instead of the traditional analog one in this new model.By analyzing the features and fields of application among MVB, LonWorks and CAN MVB is selected as train broadcasting communication network. In according to the calculation result of digital audio bandwidth, an audio compression algorithm is necessary. After comparing the characteristics and technical indicators such as compression ratio, sound quality, and bit rate and so on, MP3 is chosen as the digital audio form. TMS320DM6446 that is a DaVinci structure is used as the core processor. The ARM core is the central processor, runs user applications based on Linux operating system. The DSP core is the coprocessor, and runs MP3 encoding and decoding algorithms. The software is consisted of Linux device driver and application. For the device driver part, MVB device driver is given as an example to introduce the implementation process of Linux device drivers in detail. For the application part, this system is designed to be modular. The implementation process of each module and the key technologies involved in the realization process are introduced in detail. The prototype of the digital train broadcasting system has been designed completely, and has realized six broadcasting functions include full-duplex Cab-to-Cab announce, full-duplex emergency intercom, artifical broadcasting, auto broadcasting, OCC broadcasting and Media Player. A lab testing environment has been built, and a comprehensive test has been given for the six types of broadcasting features. Finally, the advantages and disadvantages of this work are summarized and the further work is prospected at the end of this thesis.