【作者】 王炎；

【导师】 吴宇红；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2006， 硕士

【摘要】 VoIP和嵌入式开发技术的迅速发展,使嵌入式VOIP技术成为具有广泛市场前景的重要技术。本文以上海正诚网络通信科技公司的“FreePP”项目为背景,重点研究嵌入式VoIP专用客户终端PPBox。论文在研究和分析嵌入式Linux开发平台的基础上,完成了嵌入式环境下的PPBox的结构设计,实现了该结构中多个功能模块的软件设计和代码编写,其中包括呼叫状态控制模块、UTD探测模块、话机振铃控制模块、FXO电话线路模块等。论文分析了PPBox语音编码技术和影响语音质量的相关问题,深入研究了NAT穿越的理论和技术,通过改进应用于PPBox的NAT防火墙穿越,达到良好的性能。PPBox研制涉及的技术领域跨度大,软硬开发平台多样,技术复杂度很高。论文的研究工作在PPBox的实用化中具有重要作用。目前PPBox已通过产品试验定型,在FreePP网络中投入商业运行。更多还原

【Abstract】 The fast development of VoIP applications and embedded system exploitation technology has already made implementation of VoIP on embedded system become the developing trend of VoIP product. This article is based on the“FreePP”project being carried out in Shanghai Gemtek-Systems Corporation. The main task of the project is to design and implement the PPBox, which is an update VoIP user terminal product using the smartest techniques. In this article, firstly the embedded exploitation platform of PPBox is analyzed, and then the PPBox’s architecture is implemented in this exploitation platform. What is more, several key functional modules’design and programming are completed, including call-state controller module, UTD detection module, subscriber’s ring controller module, FXO line-state module and so on. Finally, the PPBox voice coding technology is analyzed in detail as well as some relevant problems that will influence the quality of voice. Also, the NAT-crossing theory and technology are deeply researched. Through effective improvement of PPBox NAT-crossing methods, some quite satisfactory performance is retained.The research and manufacture of PPBox involves vast technological fields and kinds of software and hardware exploitation platforms, which is therefore quite complicated. The research work completed in this article will fully advance the practical application of PPBox. At present PPBox has passed product experiment and entered commercial operation in FreePP network.更多还原