The Design And Realization Of Embedded IP Phone Terminal

IP (Internet Protocol) phone terminal is basic equipment in IP phone networks, which is a kind of communication system that transmits voice signal on IP networks and takes new creative technology and is going to become a major carrier of voice service. IP phone makes analog voice into digital voice, codes voice, packs voice into packet, decodes voice, and then transmits the packet based on IP packed net environments, which makes voice communication becoming reality. It promotes the net utilizing, makes the voice cost down. Nowadays, as a next generation major operations, Domestic and international telecommunications operators has vigorously promoted IP telephony network.This IP telephone is a terminal system based on DSP+ARM+OS, with an embedded operating system and design of the separation of chip. Voice processing component including voice compression, echo elimination, quiet detection, voice packaging, and other functions are completed by the DSP processor;the embedded operating system based on ARM embedded processor complete the network transmission control and user interface support functions. Cheap and powerful embedded chips are chosen and the operating system is used, which bring two advantages to the design. The first advantage is low-cost;the other one is its functions can be expanded.The introduction of IP telephone network system begins from the system structure and key technologies, and then the entire system design and the functional planning are provided with in-depth investigations and widely research on the current epidemic situation of dedicated voice compression processor chip. After the current epidemic of an embedded systems and voice compression processor chip are researched, Based on the background and current market situation, an embedded operating system running S3C4510 chip is chosen. On the other hand, voice compression processor chip identified as dedicated chips AC4880xC-C, which supports the international common audio compression standards. In the subsequent chapter four, hardware design of IP phone terminal system and complete schematics of hardware circuit and PCB of voice processing component and the user interfacecomponents are introduced. In the chapter five, system software is introduced, which include the setup of an embedded software platform, development method of equipment based on the /^Clinux and completion of specific equipment driver. Finally, the main conclusion is given, the follow-up studies and the prospect of the system are raised.The research and implementation of the project is directly facing market requirement and selects up-to-the-minute G711, G729A, G723.1 codec and the most popular solution scheme of embedding system, which ensures the feasibility of the project and advancement and practicability of the accomplished system.