【摘要】 USB VoIP终端是一种新型的计算机终端设备,通过它人们可以用普通电话机拨打网络电话服务商提供的VoIP电话.本文提出了USB VoIP终端硬件的设计方案,描述了各功能模块的实现,阐述了固件程序和上层控制程序,对PCM、SPI的实现部分进行了时间分析,提出了高效率的A-律到线性PCM转换算法思想.更多还原

【Abstract】 USB VoIP Terminal is a new-style computer peripheral, with which VoIP calls could be made by using normal telephone sets. This paper presents hardware design of the USB VoIP Terminal with detailed explanation of its components, discusses the flow of the firmware and control software. The timing of PCM and SPI is also analyzed and finally presented a high-efficient conversion algorithm between A-law and linear PCM.更多还原