【作者】 吴胜勇；

【导师】 李新；

【作者基本信息】 重庆大学 ， 电气工程， 2004， 硕士

【摘要】 随着时代的发展和科技的进步，新的教育手段层出不穷，其中最为突出的是多媒体教育方式。多媒体系统能够提供理想的教学环境，使师生交流更为便利，有助于提高学习和教学效率。语音系统是多媒体系统中的一类重要产品，对于提高学生外语听说能力有很大的辅助作用。目前国内的相关产品是以模拟系统为主，存在很多局限。因此，研制全数字化语音系统具有一定的理论价值和十分重要的实际意义。 本论文中的数字化语音系统可以分为相对独立的五个组成部分：计算机上位机及管理子系统、计算机适配卡、主交换机、次交换机、学生终端子系统。学生终端子系统是学生与主系统进行交互的平台，计算机管理子系统是计算机上位机管理程序，相当于主系统的神经中枢，负责分析各学生终端子系统的需求，并及时、准确地作出回应。主交换机、次交换机和计算机适配卡这三部分是学生终端子系统和计算机上位机管理程序之间交互数据的信息通道。该系统是由课题组成员合作研制，共同完成的。笔者主要负责学生终端子系统和计算机适配卡两部分的工作。 论文的主要工作和成果如下： ①参与完成了数字化语音系统方案的确定、元器件的选择；独立进行该系统中学生终端子系统和计算机适配卡两部分的硬件设计、调试及软件设计、仿真、调试；配合课题组其它成员完成了整个系统的研制、调试和测试，使该系统具有课堂教学、自主学习、课堂考试等几大功能。 ②根据子系统的需要，独立设计出数字化语音系统专用的ISA适配卡，成功利用ISA总线的16位端口方式进行数据传输，波特率可以达到16 Mbps。在研制出ISA卡的基础上，设计了PCI总线到ISA总线的转接电路，由此做出了专用于该系统的PCI适配卡。 ③在所负责两个子系统中的语音压扩编解码设计时，分析了A律PCM码的特点，找出了它的一些规律，在单片机里面用查表的方法实现A律PCM码和线性PCM码之间的相互转换，同时还利用高密度可编程逻辑器件以硬件方式实现了它们之间的相互转换。 该数字化语音系统已成功应用于外语教学，具有推广到相关课程教学及学生自主学习等方面的价值。更多还原

【Abstract】 Varieties of educational methods have been emerged with the development of science and technology, and multimedia is especially prominent as one of them. 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 system 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. Author of this paper has primarily taken charge of computer adapter and students’ terminal subsystem.The primary work of this paper is as follows:(1) The author has taken part in the project formulation and devices selection, then independently designed, adjusted and debugged the hardware and software of both computer adapter and students’ terminal subsystem. Also, the author has accomplished the whole system with other group members, which can be used for in-class teaching, self-studying, class testing etc.(2) A special ISA adapter has been designed to transmit data with the baud rate of 16 Mbps by means of 16-bit port. Subsequently the author has developed the built-up connection circuit from PCI bus to ISA bus, and then designed the PCI adapter for this system.(3) The author has analyzed the characters of A-law PCM code, and found someregularities in it. The interconnection of A-law PCM code and linear PCM code was carried out by means of software in MPU or hardware in High Density Programmable Logic Device.This 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.更多还原