The Implementaton Of Audio System Based On Embedded Network

Along with the growing social demand and the increasing level of technology, telephone switching technology is in rapid development and change.Computer and communication technology have experienced rapid development,a technological revolution,as the core of digitalization,is changing the face of human society.Digital technology has become the trend. People are no longer limited to and satisfied to the manner of to see and to hear.Internet telephony has obtained rapid development. Network Telephone is often called IP phone, which is based on IP as a network layer protocol. It is a system which is used to voice communication through the computer network, the technology which is used is known as VoIP (Voice over IP). IP phone is digitized as voice signal, then transmit as data packet (Data Packet) in the IP data networks in real time fashion. SIP technology is currently in rapid development, is gradually replacing H.323 as the core VoIP protocols.The research of SIP-based VoIP end systems has become the current hot spots.This paper introduces the Samsung ARM9 2410 microprocessor core,SIP-based IP telephone terminal system design and implementation process. The article first introduces the key technologies and related agreements of VoIP, including speech coding, real-time transmission technology, signaling technology etc. Then introduces implementation process of embedded Linux system, including: Boot Loader transplantation, transplantation of embedded Linux kernel, file system construction, the driver of the implementation and migration. It mainly introduce the implementation process of VoIP phone's each module, including the SIP protocol stack modules, voice processing module, real-time transmission module, the user agent module. Upon completion of the implementation of embedded VoIP terminal, It designs and implement test project, including functional testing and performance testing, and complete the VoIP end system testing. The results show that the subject of VoIP end system designed in full compliance with design requirements, and the call quality is good.This paper briefly introduces the general principles of congestion control and related algorithms, focuses on the TCP Friendly Congestion Control, and improve TFRC protocol mainly focus on the characteristics of VoIP. Simulation results show that the improved TFRC protocol can significantly change the status of network congestion, improve bandwidth efficiency, and show TCP friendly when share bandwidth with TCP flows.