The Research Of Pure Digital Audio System

With the information times coming, educational methods with a new fashion are exhibited for us, the emergence of multimedia is especially typical. Multimedia system is able to offer ideological teaching environment where student and teacher are able to communicate more conveniently, also it can improve the efficiency of both teaching and studying. The audio s3ystem is an important part of multimedia system, which can assist student to improve their ability of speaking and listening of foreign language. Most of the related multimedia products are analogue systems; also they have many inevitable shortages in compare to the digital products. Ttherefore, the development of Pure Digital Audio system has very important theoretical and practical value.The Pure Digital Audio system in this paper has been divided into five parts by functions: computer and managing subsystem, computer adapter, primary exchange, second exchange and students' terminal subsystem. Students' terminal subsystem offers a platform for students to communicate within system. The managing subsystem is the heart of this system. It is a program on computer, which analyses the request of each students' terminal subsystem and responds correctly and quickly. Also the other three parts have formed a data transmission channel between the managing subsystem and students' terminal subsystem. The Pure Digital Audio system is developed by a good coordination of teamwork. I have primarily taken charge of computer adapter and the system of exchanges.The main works and production of the paper are as follows:1)1 have take blue print for the whole system, and use a long time to enrich it. I have finished the hardware design and the software design of computer adapter and system of exchanges.2) I have adopted the principle of the exchange between area and speed, and of the pipelining for saving resource and digital continuity. I have designed an integral DPLL for synchronization. And I have programmed for filter.3) I have compressed digital for lessening the press of data stream. And I analyzed the characters of A-law PCM code, found the regularity in it. The interconnection of A-law PCM code and linear PCM code was carried out by means of hardware in CPLDThis Pure Digital Audio system has been conducted in foreign language education successfully, and it has important extensive value when teaching in courses of similar fields or self-studying.