Development On The Voice Signal Processing And Transmission Systems In The IP Telephones

VoIP(Voice over Internet Protocol) is one of the latest progress of the telecommunication joined together with the computer technique. As the techniques of information processing and the techniques of the Integrated Circuit manufacturing developed promptly, the prices of the digital signal processors (DSP), which are the key components for VoIP, are getting lower significantly. And then the VoIP technique is getting practical applied. Secondly, the predictable market also drives the development of the VoIP technique.A method for realizing the Ethernet telephone according to ISO 802.3 protocol is presented after analyzing the domestic and international developments of the techniques of VoIP. As the same operation manner of common telephones, one of the special DSP(CT8020) is used to perform the telephone operation, collection and compression/decompression of voice signals, related data transmission control. The netcard(RTL8019AS) controller is used to perform the voice data packeted for transmission, the packets unpacked for receiving, the call control according to TCP/IP Protocol in the LAN.The paper describes two kinds of the software and hardware structure (which are based on PC and micro-controller). The feasibility of the scheme is demonstrated by experiments in the LAN. The related problems on application are also discussed.