The Hardware Design Of Voice Gateway In Unified Communications

People are already very familiar with the Internet. Now Internet has entered into households, which becomes an indispensable part in people's life. With the network technology continuous development, it brings about a new topic, that is whether it implements unified communications in wide range of business way such as voice, fax, e-mail, short messaging, multimedia, and data way in the IP network. Unified communications(UC)is a new communication model, which integrates computer network technology and traditional communication technologies. UC not only serves the people's work and life with unprecedented convenience, but also greatly reduces the cost. VoIP technology is an important branch of unified communications, while voice gateway is the core and key equipment of VoIP, and it sets up a bridge between the traditional public telephone network and IP networks and realize voice transmission of the IP network.As a terminal product, voice gateway mainly includes the hardware system and software system. This paper mainly discusses the hardware design of voice gateway based on CPU + DSP dual-core embedded structure. The modularized design method was adopted by the system, which selected MPC860 as the core of 32bit embedded system unit and TMS320VC5416 as speech processing core. System completed 4 channel data transmission under the control of the CPLD which used a 4 channel speech module as the front-end and 8bit PCM code as the coding method. The two units connected by host interface. Wind River VxWorks was used as the real-time system for voice gateway, and Tornado was the integrated development environment for the BSP debugging and application software development. The PCB of embedded system unit is 6 layers, anti-interfere processing such as network interface hollowed and SDRAM connecting line equal-length was implemented; PCB of speech unit is 4 layers, due to the existence of more analog signal, analog and digital processing was done for speech unit, such as analog ground and digital ground separated from each other. Two units connected by connector. The first edition of PCB was designed by Protel. Because SDRAM equal-length processing and telephone signal difference matching, the second edition was designed by Allegro.This first chapter described the voice gateway's purpose and significance of the study, domestic and international trends and summarize and the research content. Chapter II introduced the voice gateway from the overall structure and function, to make readers a general knowledge and understanding.Chapter III detailedly introduced voice gateway hardware implementation based on the MPC860 and TMS320VC5416.Chapter IV introduced the underlying software debugging based on the VxWorks embedded operating system. Chapter V introduced the anti-interference measures of the system. Finally, Last chapter contained the conclusions of this article, thanks and so on.