a-law การใช้

The system is consist of the main data processing board which is based onthe fpga device and fast ethernet phyceiver rtl8201l and a - law pcm data encoder and decorder chip msm7702 - 3 , and the dial - up and display board which is based on mcu . the main board would carry out the core task of data processing , such as voice data packing and unpacking , the ethernet frame processing , protocol processing , call processing , etc . the dial - up and display board would carry out the task of display the ip address which is input by consumer and status of network during talk period from the main board , and so on . in the paper the system of lan ip telephone and the tcp / ip protocol is introduced firstly , then the fpga device is stated . after that the fpga - based hardware scheme is introduced in detail in chapter four