This paper provides a description of the basic conception and principle of VoIP,especially several key technologies,which include:signaling,coding,voice activity detection,real-time transmission and guarantee of quality of network service.

and then expatiates five key technologies of VoIP: signaling,coding,voice activity detection and acoustic-echo cancellation,real-time transmission and guarantee of QOS.

Voice code technology of GSM system;

Machine design reusable coding technology and reconstruction algorithm

Utilizing the coding technology to carrying out coding on the behavior characteristics of FTU,behavior relationship of input/output and structural relationship,and the FTU knowledgebase used for the solution of motion scheme was established.

With the development of video conferencing,multimedia technology and the applications of internet,the video compression coding technology which is the core technique of video business and storage applications,has increasingly aroused people′s attention and interesting.

Based on orthogonal encoding mode in protein secondary structure prediction of neural network, a kind of encoding technology including a set of protein physical-chemical features was presented.

The design for the code salver of the encoder uses new encoding technology, which makes it easy to produce and figure simpler.