【作者】 邓勇全；

【导师】 李玲远；

【作者基本信息】 华中师范大学 ， 电路与系统， 2003， 硕士

【摘要】 IP电话是指在以IP(Internet Protocol)为网络层协议的计算机网络中进行话音通信的系统，它采用的技术通称为VoIP(Voice over IP)。VoIP是目前通信界的技术热点和应用热点。PC-PC是IP电话重要业务形式之一，它不但不需要向PSTN(Public Switched Telephone Networks)运营商支付昂贵的话费，而且能提供包括音频、视频和数据在内多层次、全方位的服务，因而受到了业界的广泛推崇。 笔者设计的网络电话属于PC-PC的IP电话通信系统。系统基于ITU的多媒体通信协议H.323，包括终端和网守两种设备。网守是网络电话通信系统的管理设备，管理所有的终端，为终端提供地址翻译和网络接入等服务。终端可以通过Internet相互呼叫，实现免费通话。终端的功能集成于PC与USB手柄。USB手柄是网络电话通信系统的一大特色。它合乎人们使用习惯，能有效消除回声干扰。经测试，系统通信稳定可靠，音质较好。 文章首先介绍IP电话的历史、发展与现状，展望其前景，分析现有产品的优缺点，论证研制网络电话的现实意义。其次介绍网络电话的体系结构及其原理。接着介绍USB手柄的原理和硬件设计、测试过程。然后介绍WDM的原理以及利用DriverStudio开发USB手柄驱动程序的方法。最后，总结网络电话设计的要点和难点，指出设计的不足，并探讨改进的方法。更多还原

【Abstract】 VoIP technology means the technology transfers packetized voice over IP networks. Network telephone is one of its typical applications. As the rapid progress of IP network technology, VoIP has become a hot topic in study and application. The application of VoIP, which used to be limit to the link from PC to PC, now has run to multi-link-patterns, including from PC to PC, PC to telephone, telephone to telephone etc.There is 2 kinds in pc to pc. The first solution of VoIP is used embedded IC. It’s difficult to develop and their price is high. The second solution utilizes the resource of pc. They are easier to use and their price is lower, but they can’t cancel echo.The Recommendation, H.323, covers the technical requirements for multimedia communications systems in those situations where the transport is a PBN(Packet-based Network) which may not provide a guaranteed QoS(Quality of Service). These networks may consist of a single network segment, or they may have complex topologies that incorporate many network segments interconnected by other communications links.My design. Networks telephone, is over the communication system of H.323, which is made up of gatekeeper and endpoints. Gatekeepers provide register control, admission control and address translation services. I had designed a USB handset in endpoint, whose functions are D/A,A/D, dial and etc. It deduced the rate of code by g.729 and cancelled the echo by some special technology.In this thesis, a systematic and comprehensive study has been conducted to design the network telephone. I first introduced the H.323 and the development of protocol, gatekeeper and client with OpenH323.Then I introduced how to design the USB handset with Tiger Jet’s solution. I discuss the program of WDM( Windows Driver Model) with DriverStudio at last.In the end, I summarize the elements and difficulties of the implementation, indicate the shortage of the design, and then discuss and approach to better it.更多还原